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twc:test-exprs
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twc:cljs
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twc:refactor-parser
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target/stale
target/js
target/classes
classes/
checkouts/
/target
/classes
/checkouts
profiles.clj
pom.xml
pom.xml.asc
*.jar
*.class
.lein-*
.nrepl-port
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.clj-kondo/
.cpcache/
**/.DS_Store
sandbox
ludus.sublime-workspace
ludus
!src/ludus
out/
node_modules/
.shadow-cljs
.cljs_node_repl/
.helix/
target/repl-port
.repl-buffer
.repl-buffer.janet
.env
src/jpm_tree
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# Change Log
All notable changes to this project will be documented in this file. This change log follows the conventions of [keepachangelog.com](http://keepachangelog.com/).
## [Unreleased]
### Changed
- Add a new arity to `make-widget-async` to provide a different widget shape.
## [0.1.1] - 2021-10-23
### Changed
- Documentation on how to make the widgets.
### Removed
- `make-widget-sync` - we're all async, all the time.
### Fixed
- Fixed widget maker to keep working when daylight savings switches over.
## 0.1.0 - 2021-10-23
### Added
- Files from the new template.
- Widget maker public API - `make-widget-sync`.
[Unreleased]: https://sourcehost.site/your-name/cludus/compare/0.1.1...HEAD
[0.1.1]: https://sourcehost.site/your-name/cludus/compare/0.1.0...0.1.1

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Ludus is copyrighted by Scott Richmond, (c) 2022, and distributed under the GNU GPL:
GNU GENERAL PUBLIC LICENSE
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101
README.md
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@ -1,93 +1,22 @@
![Ludus logo](logo.png)
## Ludus: A friendly, dynamic, functional language
Ludus is a scripting programming language that is designed to be friendly, dynamic, and functional.
# cludus
This repo currently contains a work-in-progress implementation of an interpreter for the Ludus programming language, using [Janet](https://janet-lang.org) as a host language.
Ludus is part of the [_Thinking with Computers_ project](https://alea.ludus.dev/twc/), run by Scott Richmond at the University of Toronto, with collaborator Matt Nish-Lapidus; Bree Lohman and Mynt Marsellus are the RAs for the project. Ludus is our research language, which aspires to be a free translation of Logo for the 2020s.
A Clojure library designed to ... well, that part is up to you.
Here are our design goals:
## Usage
#### Friendly
Ludus, like Logo, is meant to be a teaching language, often for students who don't think of themselves as "computer people." Our intended audience are humanities and art people at the university level (undergrads, grads, faculty). Everything is kept as simple as possible, but no simpler. Everything is consistent as possible. We aspire to the best error messages we can muster, which is important for a language to be teachable. That means being as strict as we can muster, _in order to be friendlier_.
FIXME
Our current development target is Ludus on the web: https://web.ludus.dev. That wires what we do on the langauge interpreter (here in this repo) to a web frontend.
## License
Naturally, it starts with Logo's famed turtle graphics.
Copyright © 2021 FIXME
#### Dynamic
Statically typed programming languages generally give more helpful error messages than dynamic ones, but learning a type system (even one with robust type inference) requires learning two parallel systems: the type system and the expression system (well, and the pattern system). Type systems only really make sense once you've learned why they're necessary. And their benefits seem (to us, anyway) to be largely necessary when writing long-lived, maintainable, multi-author code. Ludus code is likely to be one-off, expressive, and single-authored.
This program and the accompanying materials are made available under the
terms of the Eclipse Public License 2.0 which is available at
http://www.eclipse.org/legal/epl-2.0.
To stay friendly, Ludus is dynamic. But: despite the dynamism, we aim to be as strict as possible. Certainly, we want to avoid the type conversion shenanigans of a language like JavaScript.
#### Functional
Ludus is emphatically functional: it uses functions for just about everything. This is both because your humble PI had his world reordered when he learned his first functional language (Elixir), and because the research into Logo and the programming cultures of MIT in the 1970s revolve around extremely functional Lisp code (i.e., Scheme). Logo is a weird little language, but it is a descendant of Lisp. So is Ludus.
Also, we believe that Ludus's immutable bindings and persistent or immutable data structures and careful approach to manipulating state lead to a lot of good pedagogical results. Learning a programming language involves learning how to model what's going on inside the computer; Ludus, we think, makes that both simpler and easier.
If you're looking for cognate languages, Ludus takes a _lot_ of design inspiration from Clojure and Elixir (which itself took a lot from Clojure). (The current--quick, dirty, and slow--version of Ludus is written in [Janet](https://janet-lang.org).) Clojure and Elixir are great! If you're asking why you should use Ludus instead of them, you're already at the point where you should be using them. Ludus is, maybe, for the people whom you'd like to work with in 5 years at your Pheonix shop (but even then, probably not).
### Status
Pre-alpha, still under active development. Lots of things change all the time.
The current version of Ludus is a pure function that runs in JavaScript as a WASM blob. We have plans for more and better things.
### Use
Current emphasis is on the web version: https://web.ludus.dev.
### Main features
* Expression-oriented: everything returns a value
* Pattern matching in all the places
* No operators: everything is called as a function
* Easy-peasy partial application with placeholders
* Function pipelines
* Persistent or immutable data structures
* Careful, explicit state management using `box`es
* Clean, concise, expressive syntax
* Value-based equality; only functions are reference types
#### Under construction
* Actor-model style concurrency.
* Faster, bytecode-based VM written in a systems language, for better performance.
* Performant persistent, immutable data structures, à la Clojure.
### `Hello, world!`
Ludus is a scripting language. At current it does not have a good REPL. Our aim is to get interactive coding absolutely correct, and our efforts in [ludus-web](https://github.com/thinking-with-computers/ludus-web) are currently under way to surface the right interactivity models for Ludus.
Either:
```
"Hello, world!"
```
`=> "Hello, world!"`
Ludus scripts (and blocks) simply return their last expression; this script returns the bare string and exits.
Or:
```
print! ("Hello, world!")
```
```
=> Hello, world!
=> :ok
```
Here, we use the `print!` function, which sends a string to a console (`stdout` on Unix, or a little console box on the web). Because `print!` returns the keyword `:ok` when it completes, that is the result of the last expression in the script--and so Ludus also prints this.
### Some code
Fibonacci numbers:
```
& fibonacci!, with multi-clause fns/pattern matching
fn fib {
"Returns the nth fibonacci number."
(1) -> 1
(2) -> 1
(n) -> add (
fib (sub (n, 1))
fib (sub (n, 2)))
}
fib (10) &=> 55
```
### More on Ludus
See the [language reference](language.md) and [the documentation for the prelude](prelude.md).
This Source Code may also be made available under the following Secondary
Licenses when the conditions for such availability set forth in the Eclipse
Public License, v. 2.0 are satisfied: GNU General Public License as published by
the Free Software Foundation, either version 2 of the License, or (at your
option) any later version, with the GNU Classpath Exception which is available
at https://www.gnu.org/software/classpath/license.html.

130
build/driver.cpp
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#include <cstdint>
#include <emscripten.h>
#include <emscripten/bind.h>
#include <string>
#include <stdio.h>
#include "janet.h"
using std::string;
// set all our exported Janet functions as null pointers
static JanetFunction *janet_ludus = NULL;
// these let us look up functions
Janet env_lookup(JanetTable *env, const char *name) {
Janet out;
janet_resolve(env, janet_csymbol(name), &out);
return out;
}
JanetFunction *env_lookup_function(JanetTable *env, const char *name) {
Janet value = env_lookup(env, name);
if (!janet_checktype(value, JANET_FUNCTION)) {
janet_panicf("expected %s to be a function, got %q\n", name, value);
}
return janet_unwrap_function(value);
}
// this lets us call a function
bool call_fn(JanetFunction *fn, int argc, const Janet *argv, Janet *out) {
JanetFiber *fiber = NULL;
if (janet_pcall(fn, argc, argv, out, &fiber) == JANET_SIGNAL_OK) {
return true;
} else {
janet_stacktrace(fiber, *out);
return false;
}
}
// this is darkish magic, reads an embedded file
// do not fuck with this, fellas
unsigned char *read_file(const char *filename, size_t *length) {
size_t capacity = 2 << 17;
unsigned char *src = (unsigned char *)malloc(capacity * sizeof(unsigned char));
assert(src);
size_t total_bytes_read = 0;
FILE *file = fopen(filename, "r");
assert(file);
size_t bytes_read;
do {
size_t remaining_capacity = capacity - total_bytes_read;
if (remaining_capacity == 0) {
capacity <<= 1;
src = (unsigned char*)realloc(src, capacity * sizeof(unsigned char));
assert(src);
remaining_capacity = capacity - total_bytes_read;
}
bytes_read = fread(&src[total_bytes_read], sizeof(unsigned char), remaining_capacity, file);
total_bytes_read += bytes_read;
} while (bytes_read > 0);
fclose(file);
*length = total_bytes_read;
return src;
}
// finally, getting a string back
// this is our result type
struct StringResult {
string value;
};
// this is our result constructor
// Janet's getcstring resturns const char*
StringResult string_result(const char* cstr) {
// ...which we have to cast to a std::string
return (StringResult) {.value = (string) cstr };
}
// and this is a function that takes and returns a string
// it returns a StringResult, tho
StringResult ludus(string source) {
Janet result;
const Janet args[1] = {janet_cstringv(source.c_str())};
call_fn(janet_ludus, 1, args, &result);
// get the cstring in the result
// the 0 passed here is the index in the result of the string
const char* cstr = janet_getcstring(&result, 0);
// return a constructed StringResult
return string_result(cstr);
}
// This function sets up our Janet interpreter, and fixes the null pointers
EMSCRIPTEN_KEEPALIVE
int main() {
janet_init(); // start the interpreter
JanetTable *core_env = janet_core_env(NULL); // get a core env
JanetTable *lookup = janet_env_lookup(core_env); // and get an env table
// load the janet image into memory
// note that the image is hardcoded here
size_t image_length;
unsigned char *image = read_file("ludus.jimage", &image_length);
// load the image into the Janet environment
Janet env = janet_unmarshal(image, image_length, 0, lookup, NULL);
if(!janet_checktype(env, JANET_TABLE)) {
janet_panicf("invalid image %q", env);
}
// fix the null pointers, as above
// note that the bound symbols are just the normal fn names
// no namespacing
janet_ludus = env_lookup_function(janet_unwrap_table(env), "ludus");
janet_gcroot(janet_wrap_function(janet_ludus));
}
// these bindings are exported into javascript
EMSCRIPTEN_BINDINGS(module) {
using namespace emscripten;
// these are the functions that will be available
function("ludus", &ludus, allow_raw_pointers());
// we also want a wrapper for our StringResult
// we won't access it directly, but emcc makes it nice
value_object<StringResult>("StringResult")
.field("value", &StringResult::value);
}

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build/justfile
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build:
# the complex emscripten invocation
# note we have the stack size set to 1024*1024 (1 MB)
emcc \
-o out.mjs \
janet.c driver.cpp \
--embed-file ludus.jimage \
-lembind \
-s "EXPORTED_FUNCTIONS=['_main']" \
-s EXPORT_ES6 \
-s ALLOW_MEMORY_GROWTH=1 \
-s STACK_SIZE=1048576 \
-s MODULARIZE

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build/ludus.mjs
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import init from "./out.mjs"
const mod = await init()
export function run (source) {
const result = mod.ludus(source).value
console.log(result)
return JSON.parse(result)
}

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build/test.mjs
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import {run} from "./ludus.mjs"
console.log(run(`let foo = 42; "{foo} bar"`))

7
deps.edn Normal file
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@ -0,0 +1,7 @@
{
:dependencies [nrepl "0.9.0"]
:aliases {:nREPL
{:extra-deps
{nrepl/nrepl {:mvn/version "0.9.0"}}}}
}

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doc/intro.md Normal file
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# Introduction to cludus
TODO: write [great documentation](http://jacobian.org/writing/what-to-write/)

31
justfile
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@ -1,31 +0,0 @@
# open a janet repl in a different os window
repl:
kitten @ launch --type=os-window --allow-remote-control --cwd=current --title=hx_repl:ludus --keep-focus
kitten @ send-text -m "title:hx_repl:ludus" "janet -s\n"
# restart the repl server
restart:
kitten @ send-text -m "title:hx_repl:ludus" "\04"
kitten @ send-text -m "title:hx_repl:ludus" "janet -s\n"
# send what's selected to the repl and evaluate it
eval:
sd "$" "\n" | sd "\n\n" "\n" | kitten @ send-text -m "title:hx_repl:ludus" --stdin
# get documentation for a symbol in janet/clojure
doc:
sd "$" "\n" | sd "\n\n" "\n" | xargs -I _ echo "(doc " _ ")" | kitten @ send-text -m "title:hx_repl:ludus" --stdin
# publish to npm (did you build things first?)
publish:
npm version patch
npm publish
# build the ludus jimage
build:
rm build/out.mjs
rm build/out.wasm
rm build/ludus.jimage
janet -c src/ludus.janet build/ludus.jimage
cd build && just build
git commit -am "build"

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@ -1,513 +0,0 @@
# Ludus language reference
This is not intended for beginners, but to be a language overview for experienced programmers. That said, it may help beginners orient themselves in the language.
## Comments
Ludus's comment character is `&`. Anything after an ampersand on a line is ignored. There are no multiline comments.
## Atomic values
Ludus has four types of atomic values.
### `nil`
`nil` is Ludus's representation of nothing. In the grand Lisp tradition, Ludus can, and occasionally does, use `nil`-punning. Its type is `:nil`.
### Booleans
`true` and `false`. That said, in all conditional constructs, `nil` and `false` are "falsy," and everything else is "truthy." Their type is `:boolean`.
### Numbers
Ludus has numbers, which are IEEE-754 64-bit floats. Numbers are more complicated than you think, probably.
Number literals in Ludus are either integers or decimal floating point numbers, e.g. `32.34`, `42`, `-0.23`. Underscores in numbers are ignored, and can be used to separate long numbers, e.g. `1_234_567_890`.
Numbers' type is `:number`.
### Keywords
Ludus keywords begin with a colon and a letter, e.g. `:keyword`. Types are represented as keywords. Some functions take an optional units argument as a keyword, e.g. `:radians`. Keywords are also used as keys for associative collections. Keywords' type is `:keyword`.
Keywords must begin with an ASCII upper- or lower-case letter, and can then include any letter character, as well as `_`, `/`, `!`, `?`, and `*`.
## Strings
Ludus strings are UTF-8 strings, and only use double quotes. Strings may be multiline. For example, this is a string: `"foo"`. So is this:
```
"foo
bar baz"
```
Strings use backslashes for escapes, including `\n` for newline, `\t` for tab, `\"` for a double quote, and `\{` for an open curly brace (see below on interpolation).
Strings' type is `:string`.
### String interpolation
Strings may also insert a string representation of any Ludus value that is bound to a name, by inserting that name in curly braces. To wit,
```
let foo = :foo
let bar = 42
let baz = [1, 2, 3]
"{foo} {bar} {baz}" &=> ":foo 42 1, 2, 3"
```
Interpolations may _not_ be arbitrary expressions: only bound names may be used in interpolations.
## Collections
Ludus has a few different types of collections, in increasing order of complexity: tuples, lists, sets, dicts, and packages. All collections are immutable.
#### Separators
In all collection literals, members are written with a separator between them. On the same line, use a comma; or a newline will also separate elements. You may use as many separators as you wish at any point inside a collection or pattern. `(,,,,,,,3,,4,,,,,,)` and `(3, 4)` are the same value.
#### Efficiency
At the current moment, Ludus collections are all copy-on-write; this means that Ludus is _not_ performant with large collections. Eventually, Ludus will have Clojure-style persistent, immutable collections.
### Tuples
Tuples are fully-immutable, ordered collections of any kinds of values, delimited by parentheses, e.g. `(1, :a, "foo")`. At current, they have no length limit (although they eventually will). Unlike in some languages, tuples can be empty or contain a single element: `()` and `(:foo)` are both just fine. Tuples largely cannot be manipulated functionally; they must be written as literals and unpacked using pattern matching. They can, however, be converted to lists, either through pattern matching or the `list` function. Their type is `:tuple`.
### Lists
Lists are persistent and immutable ordered collections of any kinds of values, delimited by square braces, e.g. `[1, :a, "foo"]`. Their type is `:list`.
Lists may be combined using splats, written with ellipses, e.g., `[...foo, ...bar]`.
### Sets
Sets are persistent and immutable unordered collections of any kinds of values, which can only contain one instance of any given value. They are written similarly to ordered collections: `${1, :a, "foo"}`. Their type is `:set`.
### Dictionaries, or dicts
Dicts are persistent and immutable associative collections of any kinds of values. Dicts use keywords as keys (and cannot use any other kind of Ludus value as a key, not even strings), but can store any values. Dict literals are written as keyword-value pairs: `#{:a 1, :b false}`. Single words may be used as a shorthand for a key-value pair. Accessing a key that holds no value returns `nil`. Their type is `:dict`.
### Packages
Packages are immutable collections of bindings. They may only be described at the top level of a script, and their names must begin with a capital letter. Accessing a key that has no value on a package results in a validation error. They may not be accessed using functions, but only direct keyword access. Their type is `:pkg`.
They are written with the form `pkg`, then a package name, beginning with a capital letter, that will be bound as their name, and then an associative structure (pairs or word shorthands), delimited by `{}`, e.g.:
```
pkg Foo {
:bar "bar"
:baz 42
quux
}
```
### Working with collections
Ludus names are bound permanently and immutably. Collections are immutable. How do you add something to a list or a dict? How do you get things out of them?
Ludus provides functions that allow working with persistent collections. They're detailed in [the Prelude](prelude.md). That said, all functions that modify collections take a collection and produce the modified collection _as a return value_, without changing the original collection. E.g., `append ([1, 2, 3], 4)` will produce `[1, 2, 3, 4]`, but the original list is unchanged. (For dicts, the equivalent is `assoc`.)
## Expressions
Ludus is an expression-based language: all forms in the language are expressions and return values, except `panic!`. That said, not all expressions may be used everywhere.
### Terminating expressions
Expressions in scripts and blocks are terminated by a newline or a semicolon. In compound forms, like, `if`, the terminator comes after the `else` expression.
In forms with multiple clauses surrounded by curly braces (i.e., function bodies, `match`, `when`, etc.), you may separate clauses with semicolons as well as newlines.
### Toplevel expressions
Some expressions may only be used in the "top level" of a script. Because they are the toplevel, they are assured to be statically knowable. These include: `pkg`, `ns`, `use`, `import`, and `test`. (NB: not all of these are yet implemented.)
### Non-binding expressions
Some forms may take any expression that does _not_ [bind a name](#words-and-bindings), for example, any entry in a collection, or the right-hand side of a `let` binding. This is because binding a name in some positions is ambiguous, or nonsensical, or leads to unwarranted complications.
### Simple expressions
Many compound forms will only accept "simple" expressions. Formally, simple expressions are either literal (atomic, string, or collection literals) or synthetic expressions. They are expressions which do not take sub-expressions: no `if`, `when`, `match`, etc. (`do` expressions are currently not simple, but that may be revised.)
## Words and bindings
Ludus uses _words_ to bind values to names. Words must start with a lower case ASCII letter, and can subsequently include any letter character (modulo backing character encoding), as well as , `_`, `/`, `?`, `!`, and `*`.
Ludus binds values to names immutably and permanently: no name in the same scope may ever be re-bound to a different value. (Although see [boxes](#boxes-and-state), below.
Attempting to use an unbound name (a word that has not had a value bound to it) will result in a validation error, and the script will not run.
### `let` bindings: a very short introduction
Ludus's basic binding form is `let`:
```
let foo = :bar & `foo` is now bound to `bar` for the rest of the scope.
let foo = :baz & Validation error: name foo was bound in line 1
```
`let` bindings are more complex; we will return to these below.
## Patterns
Ludus makes extensive use of pattern-matching. Patterns do two jobs at once: they match values (or don't); and they bind names. The left-hand side of the examples just above in the `let` binding is not just a word: it is a pattern. Patterns also arise in conditional forms and function declarations.
### The placeholder: `_`
The simplest pattern is the placeholder: it matches against anything, and does not bind a name. It is written as a single underscore: `_`, e.g., `let _ = :foo`.
#### Ignored names
If you wish to be a bit more explict than using a placeholder, you can use an ignored name, which is a name that starts with an underscore: `_foo`. This is not bound, is not a valid name, and can be used however much you wish, even multiple times in the same pattern. It is, in fact, a placeholder, plus a reader-facing description.
### Literal patterns
Patterns can be literal atomic values or strings: `0`, `false`, `nil`, `:foo`, etc. That means you can write `let 0 = 0` or `let :foo = :foo`, and, while nothing will happen, everything will be just fine.
Literals match against, well, literal values: if the pattern and the value are the same, they match! If not, they don't match.
Literal values do not bind anything.
### Word patterns
Word patterns match against any value, and bind that value to the word as a name. The scope of that binding depends on the form the pattern is in. `let foo = :bar` binds `:bar` to `foo` for the rest of the scope.
#### Typed patterns
Word patterns can, optionally, take a type, using the `as` reserved word, and the keyword representing the desired type: `let foo as :number = 42`.
### String patterns
Ludus has a simple but powerful form of string pattern matching that mirrors string interpolation. Any word inside curly braces in a string will match against a substring of a string passed into a pattern.
```
let i_am = "I am the walrus"
let "I {verb} the {noun}" = i_am
(verb, noun) &=> ("am", "walrus")
```
Note that such names may well be bound to empty strings: a match does not guarantee that there will be anything in the string. This is particularly relevant at the beginning and end of string patterns:
```
let we_are = "We are the eggmen"
let "{first}We {what}" = we_are
(first, what) &=> ("", "are the eggmen")
```
### Collection patterns
Tuples, lists, and dicts can be destructured using patterns. They are written nearly identically to their literal counterparts. Collection patterns are composed of any number of simpler patterns or other collection patterns. They bind any names nested in them, match literals in them, etc.
#### Tuple patterns
Tuple patterns are delimited using parens, using commas or newlines to separate any number of other patterns. Consider `let (x, y, z) = (1, 2, 3)`. `x`, `y`, and `z` are now bound to 1, 2, and 3, respectively.
The last item in a tuple pattern can be a splat--`...`--which either discards any remaining unenumerated values in a tuple, or binds them to a list. Without a splat, tuples patterns only match against tuples of the same length.
```
let mytup = (1, 2, 3)
let (x, _, y) = mytup & x is now 1, y is now 3
let (a, ...) = mytup & a is now 1; a bare splat (without a name) is just fine
let (_, ...cs) = mytup & cs is now [2, 3]
let (p, q) = mytup & panic! no match
let () = () & empty tuples are also patterns
```
#### List patterns
List patterns are identical to tuple patterns, but they are written using square braces. They also match against a specific number of members, and may take a splat in the last position, e.g. `let [first, ...rest] = [1, 2, 3]`.
Note that list patterns, like tuple patterns, match on explicit length. That means that if you are matching only the first items of a list, you must explicitly include a splat pattern, e.g. `let [first, second, ...] = [1, 2, 3, 4]`.
#### Dict patterns
Dict patterns are written either with shorthand words, or keyword-pattern pairs. Consider: `let #{:a foo, :b 12, c} = #{:a 1, :b 12, :c 4}`. `foo` is now 1; `b` is now 12, `c` is now 4. If a dict does not hold a value at a particular key, there is no match.
Dict patterns may also use a splat as their last member: `let #{:a 1, ...b} = #{:a 1, :b 2, :c 3}` will bind `b` to `#{:b 2, :c 3}`.
Like tuple and list patterns, dict patterns without a splat at the end match only on exact equivalence on all keys.
## `let` bindings
`let` bindings are the basic form of matching and binding in Ludus. It is written `let {pattern} = {non-binding expression}`. The pattern can be arbitrarily complex. If the left-hand side of a `let` binding does not match, Ludus will raise a panic, halting evaluation of the script.
## Scope and blocks
Ludus is lexically scoped. Bindings are valid for the remainder of the scope they act on. To introduce a new scope, Ludus uses a block, a collection of expressions delimited by curly braces and separated by semicolons or newlines. The value of a block, as well as the value of a script, is the last expression in it. In `let foo = {:this; :set; :of; :expressions; "is actually"; :ignored }`, `foo` will be bound to `:ignored`.
That said, you can use bindings in blocks, which will not be available outside that block--but blocks can use bidnings from their parent scope:
```
let outer = 42
let first = {
let inner = 23
add (outer, inner)
} & first is now bound to 65
inner & Validation error: unbound name inner
```
### Shadowing
Even though names are bound permanently in Ludus, it is perfectly possible (and occasionally quite useful) to "shadow" names from an enclosing scope.
```
let x = 42
let y = {
let first = x
let x = 23 & this is fine
let second = x
add (first, second)
} & y is now 65
```
## Conditional forms
Ludus has a robust set of conditional forms, all of which are expressions and resolve to a single value.
### `if`
`if` evaluates a condition; if the result of the condition is truthy, it evaluates is `then` branch; if the condition is falsy, it evaluates its `else` branch. Both branches must always be present. Newlines may come before `then` and `else`.
`if {simple expression} then {non-binding expression} else {non-binding expression}`
### `when`
`when` is like Lisp's `cond`: it takes a series of clauses, separated by semicolons or newlines, delimited by curly braces. Clauses are written `lhs -> rhs`. `when` expressions are extremely useful for avoiding nested `if`s.
The left hand of a clause is a simple expression; the right hand of a clause is any expression. When the left hand is truthy, the right hand is evaluated, and the result of that evaluation is returned; no further clauses are evaluated. If no clause has a truthy left-hand value, then a panic is raised. In the example below, not the use of literal `true` as an always-matching clause.
```
when {
maybe () -> :something
mabye_not () -> :something_else
true -> :always
}
```
### `match`
A `match` form is the most powerful conditional form in Ludus. It consists of a test expression, and a series of clauses. The test expression must be a simple expression, followed by `with`, and then a series of clauses separated by a semicolon or newline, delimited by curly braces.
```
match may_fail () with {
(:ok, value) -> calculate_result (value)
(:err, msg) -> { log! (msg); recover_somehow () }
}
```
The left hand of a match clause is a pattern; the right hand is an expression: `pattern -> expression`. If the pattern matches the test expression of a clause, the expression is evaluated with any bindings from the pattern, and `match` form evaluates to the result of that expression.
If a test expression does not match against any clause's pattern, a panic is raised.
Ludus does not attempt to do any exhaustiveness checking on match forms; match errors are always runtime errors.
#### Guards
`match` clauses may have a _guard expression_, which allows a clause only to match if the expression's result is truthy. In the previous example, consider that we might want different behaviour depending on the value of the number:
```
match may_fail () with {
(:ok, value) if pos? (value) -> calculate_positive_result (value)
(:ok, value) if neg? (value) -> calculate_negative_result (value)
(:ok, 0) -> do_something_with_zero ()
(:err, msg) -> { log! (msg); recover_somehow () }
}
```
## Functions
Ludus is an emphatically functional language. Almost everything in Ludus is accomplished by applying functions to values, or calling functions with arguments. (These are precise synonyms.)
Functions have the type `:fn`.
### Calling functions
Functions are called by placing a tuple with arguments immediately after a function name, e.g. `add (1, 2)` adds `1` and `2`. Because they are represented as tuples, arguments must be explicitly written; splats cannot be used to pass an arbitrary number of arguments to a function.
### Defining functions
Functions have three increasingly complex forms to define them. All of them include the concept of a function clause, which is just a match clause whose left hand side must be a _tuple_ pattern.
#### Anonymous lambda
An anonymous lambda is written `fn {tuple pattern} -> {expression}`, `fn (x, y) -> if gt? (x, y) then x else add (x, y)`. Lambdas may only have one clause.
#### Named functions
A named function is identical to a lambda, with the one change that a word follows the `fn` reserved word: `fn {name} {tuple pattern} -> {expression}`. E.g., `fn add_1 (x) -> add (x, 1)`. The name of the function is bound for the remainder of the scope.
#### Compound functions
Compound functions are functions that have multiple clauses. They must be named, and in place of a single clause after a name, they consist in one or more clauses, separated by semicolons or newlines, delimited by curly braces. Optionally, compound functions may have a docstring as their first element after the opening curly brace. The docstring explains the function's purpose and use, before any of the function clauses.
An example from Ludus's Prelude:
```
fn some {
"Takes a possibly `nil` value and a default value. Returns the value if it's not `nil`, returns the default if it's `nil`."
(nil, default) -> default
(value, _) -> value
}
```
### Closures
Functions in Ludus are closures: function bodies have access not only to their specific scope, but any enclosing scope. That said, functions only have access to names bound _before_ they are defined; nothing is hoisted in Ludus.
### Mutual recursion and forward declaration
If you try the following, you'll get a validation error:
```
fn stupid_odd? {
(0) -> false
(x) -> supid_even? (dec (x)) & Validation error: unbound name stupid_even?
}
fn stupid_even? {
(0) -> true
(x) -> stupid_odd? (dec (x))
}
```
To allow for mutual recursion, Ludus allows forward declarations, which are written `fn name` without any clauses. In the example above, we would simply put `fn stupid_even?` before we define `stupid_odd?`.
If you declare a function without defining it, however, Ludus will raise a validation error.
### The Prelude
The Prelude is a substantial set of functions that is available in any given Ludus script. (It is, itself, just a Ludus file that has special access to host functions.) Because of that, a large number of functions are always available. The prelude documentation is [here](prelude.md).
### Partial application
Functions in Ludus can be partially applied by using a placeholder in the arguments. Partial application may only use a single placeholder (partially applied functions are always unary), but it can be anywhere in the arguments: `let add_1 = add(1, _)` or `let double = mult(_, 2)`.
Unary functions and called keywords may _not_ be partially applied: it is redundant.
Because of "partial application," Ludus has a concept of an "argument tuple" (which may include a single placeholder) in addition to a tuple literal (which may not include a placeholder).
### Function pipelines, or `do` forms
In place of nesting function calls inside other function calls, Ludus allows for a more streamlined version of function application: the `do` form or function pipeline. `do` is followed by an initial expression. `do` expressions use `>` as an operator: whatever is on the left hand side of the `>` is passed in as a single argument to whatever is on its right hand side. For example:
```
let silly_result = do 23 >
mult (_, 2) > add (1, _) >
sub (_, 2) > div (_, 9) & silly_result is 5
```
Newlines may appear after any instance of `>` in a `do` expression. That does, however, mean that you must be careful not to accidentally include any trailing `>`s.
### Called keywords
Keywords may be called as functions, in which case they extract the value stored at that key in the value passed in:
```
let foo = #{:a 1, :b 2}
let bar = :a (foo) & `bar` is now 1
```
Called keywords can be used in pipelines.
In addition, keywords may be called when they are bound to names:
```
let foo = #{:a 1, :b 2}
let bar = :a
bar (foo) & => 1
```
## Synthetic expressions
Synthetic expressions are valid combinations of words, keywords, package names, and argument tuples which allow for calling functions and extracting values from associative collections. The root--first term--of a synthetic expression must be a word or a keyword; subsequent terms must be either argument tuples or keywords.
```
let foo = #{:a 1, :b #{:c "bar" :d "baz"}}
let bar = foo :b :c & `bar` is now "bar"
let baz = :b (foo) :d & `baz` is now "baz"
```
## Looping forms
Ludus has optimized tail calls--the most straightforward way to accomplish repeating behaviour is function recursion. There are two additional looping forms, `repeat` and `loop`.
### `repeat`
`repeat` is a help to learners, and is useful for executing side effects multiple times. It is written `repeat {number|word} { {exprs} }`. From turtle graphics:
```
repeat 4 {
forward! (100)
right! (0.25)
}
```
Note that `repeat` does two interesting things:
1. It never returns a value other than `nil`. If it's in the block, it disappears. This is a unique (and frankly, undesirable) property in Ludus.
2. Unlike everything else in Ludus, repeate _requires_ a block, and not simply an expression. You cannot write `repeat 4 forward! (100)`.
### `loop`/`recur`
`loop` and `recur` are largely identical to recursive functions for repetition, but use a special form to allow an anonymous construction and a few guard rails.
The syntax here is `loop <tuple> with { <function clauses> }`. (Or, you can have a single function clause instead of a set of clauses.) The tuple is passed in as the first set of arguments.
```
let xs = [1, 2, 3, 4]
loop (xs, 0) with {
([x], sum) -> add (x, sum) & matches against the last element of the list
([x, ...xs], sum) -> recur (xs, add (x, sum)) & recurs with the tail
} &=> 10
```
`recur` is the recursive call. It must be in tail position--`recur` must be the root of a synthetic expression, in return position. If `recur` is not in tail position, a validation error will be raised.
In addition, `recur` calls must have the same number of arguments as the original tuple passed to `loop`. While Ludus will allow you to write clauses in `loop` forms with a different arity than the original tuple, those will never match.
`recur` calls return to the nearest `loop`. Nested `loop`s are probably a bad idea and should be avoided when possible.
## Environment and context: the toplevel
The "toplevel" of a script are the expressions that are not embedded in other expressions or forms: not inside a block, not a member of a collection, not on the right hand side of a binding, not inside a function body. The toplevel-only forms:
### `import`
`import` allows for the evaluation of other Ludus scripts: `import "path/to/file" as name`. `import` just evaluates that file, and then binds a name to the result of evaluating that script. This, right now, is quite basic: circular imports are currently allowed but will lead to endless recursion; results are not cached, so each `import` in a chain re-evaluates the file; and so on.
Status: not yet implemented.
### `use`
`use` loads the contents of a namespace into a script's context. To ensure that this is statically checkable, this must be at the toplevel.
Status: not yet implemented.
### `pkg`
Packages, `pkg`es, may only be described at the toplevel of a script. This is to ensure they can be statically evaluatable.
### `test`
A `test` expression is a way of ensuring things behave the way you want them to. Run the script in test mode, and these are evaluated. If the expression under `test` returns a truthy value, you're all good! If the expression under `test` returns a falsy value or raises a panic, then Ludus will report which test(s) failed.
```
test "something goes right" eq? (:foo, :foo)
test "something goes wrong" {
let foo = :foo
let bar = :bar
eq? (foo, bar)
} &=> test failed: "something goes wrong" on line 3
```
`test`s must be at the toplevel--or embedded within other tests in _their_ highest level.
Formally: `test <string> <expression>`.
Status: not yet implemented.
## Changing things: `box`es
Ludus does not let you re-bind names. It does, however, have a type that allows for changing values over time: `box`. A box is a place to put things, it has its own identity, it can store whatever you put in it, but to get what's in it, you have to `unbox` it.
Syntactically and semantically, `box`es are straightforward, but do require a bit more overhead than `let` bindings. The idea is that Ludus makes it obvious where mutable state is in a program, as well as where that mutable state may change. It does so elegantly, but with some guardrails that may take a little getting used to.
The type of a `box` is, predictably, `:box`.
```
box foo = 42 & foo is now bound to a _box that contains 42_
add (1, foo) & panic! no match: foo is _not_ a number
store! (foo, 23) & foo is now a box containing 23
update! (foo, inc) & foo is now a ref containing 24
unbox (foo) &=> 23; use unbox to get the value contained in a box
```
### Ending with a bang!
Ludus has a strong naming convention that functions that change state or could cause an explicit panic end in an exclamation point (or, in computer nerd parlance, a "bang"). So anything function that mutates the value held in a reference ends with a bang: `store!` and `update!` take bangs; `unbox` does not.
This convention also includes anything that prints to the console: `print!`, `report!`, `doc!`, `update!`, `store!`, etc.
(Note that there are a few counter-examples to this: math functions that could cause a panic [in place of returning NaN] do not end with bangs: `div`, `inv`, and `mod`; each of these has variants that allow for more graceful error handling).
### Ending with a whimper?
Relatedly, just about any function that returns a boolean value is a predicate function--and has a name that ends with a question mark: `eq?` tests for equality; `box?` tells you if something is a ref or not; `lte?` is less-than-or-equal.
## Errors: panic! in the Ludus script
A special form, `panic!`, halts script execution with the expression that follows as an error message.
```
panic! :oops
if true then :ok else panic! "It's false!"
```
Panics also happen in the following cases:
* a `let` binding pattern has no match against the value of its expression
* a `match` or `when` form has no matching clause
* a function is called with arguments that do not match any of its clauses
* something that is not a function or keyword is called as a function
* a called keyword is partially applied
* `div`, `inv`, or `mod` divides by zero
* `sqrt` takes the square root of a negative number
* certain error handling functions, like `unwrap!` or `assert!`, are invoked on values that cause them to panic
In fact, the only functions in the Prelude which explicitly cause panics are, at current, `div`, `inv`, `mod`, `sqrt`, `unwrap!`, and `assert!`.
### `nil`s, not errors
Ludus, however, tries to return `nil` instead of panicking where it seems prudent. So, for example, attempting to get access a value at a keyword off a number or `nil`, while nonsensical, will return `nil` rather than panicking:
```
let a = true
a :b :c :d :e &=> nil
let b = [1, 2, 3]
at (b, 12) &=> nil
```
### Result tuples
Operations that could fail--especially when you want some information about why--don't always return `nil` on failures. Instead of exceptions or special error values, recoverable errors in Ludus are handled instead by result tuples: `(:ok, value)` and `(:err, msg)`. So, for example, `unwrap!` takes a result tuple and either returns the value in the `:ok` case, or panics in the `:err` case.
Variants of some functions that may have undesirably inexplicit behaviour are written as `{name}/safe`. So, for example, you can get a variant of `div` that returns a result tuple in `div/safe`, which returns `(:ok, result)` when everything's good; and `(:err, "division by zero")` when the divisor is 0.

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{
"source": ["./target/ludus"],
"bundle_id": "dev.ludus.core",
"apple_id": {
"username": "s.richmond@utoronto.ca",
"password": "@keychain:Notary"
},
"sign": {
"application_identity": "9F27C69TKX"
},
"dmg": {
"output_path": "./target/ludus.dmg",
"volume_name": "Ludus"
}
}

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{
"name": "@ludus/ludus-js-pure",
"version": "0.1.26",
"description": "A Ludus interpreter in a pure JS function.",
"type": "module",
"main": "build/ludus.mjs",
"directories": {},
"keywords": [],
"author": "Scott Richmond",
"license": "GPL-3.0",
"files": [
"build/out.wasm",
"build/out.mjs",
"build/ludus.mjs"
],
"devDependencies": {}
}

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& this file runs after any given interpretation
& even if the original interpretation panics
& the goal is to output any global state held in Ludus
& this does not have base loaded into it, only prelude: must be pure Ludus
if turtle_state () :visible? then render_turtle! () else nil
reset_turtle! ()
& let console_msgs = flush! ()
let (r, g, b, a) = unbox (bgcolor)
store! (bgcolor, colors :black)
let draw_calls = unbox (p5_calls)
store! (p5_calls, [])
#{
& :result result is provided elsewhere
& :errors [] & if we get here there are no errors
& :console console_msgs
:draw concat (
[(:background, r, g, b, a), (:stroke, 255, 255, 255, 255)]
draw_calls)
}

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(defproject ludus "0.1.0-SNAPSHOT"
:description "FIXME: write description"
:url "http://example.com/FIXME"
:license {:name "EPL-2.0 OR GPL-2.0-or-later WITH Classpath-exception-2.0"
:url "https://www.eclipse.org/legal/epl-2.0/"}
:dependencies [[org.clojure/clojure "1.10.3"]]
:plugins [[lein-cljfmt "0.8.0"]]
:repl-options {:init-ns ludus.core}
:main ludus.core)

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let input = "I remember my mother"
print! ("DOCTOR")
print! ("> ", input)
let sanitized = do input > trim > downcase
& ensuring we have spaces at the beginning and end
& this lets us match patterns as written below
let padded = join ([" ", sanitized, " "])
fn switch_persons {
("i") -> "you"
("you") -> "i"
("am") -> "are"
("me") -> "you"
("my") -> "your"
(x) -> x
}
fn repersonalize (x) -> do x >
trim >
split (_, " ") >
map (switch_persons, _) >
join (_, " ")
fn one_of {
(str as :string) -> str
(strs as :list) -> random (strs)
}
let output = match padded with {
"{x} hello {y}" -> "How do you do. Please state your problem"
"{x} hi {y}" -> "How do you do. Please state your problem"
"{x} computer {y}" -> [
"Do computers worry you"
"What do you think about machines"
"Why do you mention computers"
"What do you think machines have to do with your problem"
]
"{x} name {y}" -> "I am not interested in names"
"{x} sorry {y}" -> [
"Please don't apologize"
"Apologies are not necessary"
"What feelings do you have when you apologize"
]
"{x} i remember {y}" -> {
let switched = repersonalize (y)
[
"Do you often think of {switched}"
"Does thinking of {switched} bring anything else to mind"
"What else do you remember"
"Why do you recall {switched} right now"
"What in the present situation reminds you of {switched}"
"What is the connection between me and {switched}"
]
}
"{x} do you remember {y}" -> {
let switched = repersonalize (y)
[
"Did you think I would forget {switched}"
"Why do you think I should recall {switched} now"
"What about {switched}"
"You mentioned {switched}"
]
}
"{x} if {y}" -> {
let switched = repersonalize (y)
[
"Do you reall think that its likely that {switched}"
"Do you wish that {switched}"
"What do you think about {switched}"
"Really--if {switched}"
]
}
"{x} i dreamt {y}" -> {
let switched = repersonalize (y)
[
"Really--{y}"
"Have you ever fantasized {y} while you were awake"
"Have you dreamt {y} before"
]
}
"{x} dream about {y}" -> {
let switched = repersonalize (y)
"How do you feel about {switched} in reality"
}
"{x} dream {y}" -> [
"What does this dream suggest to you"
"Do you dream often"
"What persons appear in your dreams"
"Don't you believe that dream has to do with your problem"
]
"{x} my mother {y}" -> {
let switched = repersonalize (y)
[
"Who else in your family {y}"
"Tell me more about your family"
]
}
"{x} my father {y}" -> [
"Your father"
"Does he influence you strongly"
"What else comes to mind when you think of your father"
]
"{x} i want {y}" -> {
let switched = repersonalize (y)
[
"What would it mean if you got {y}"
"Why do you want {y}"
"Suppose you got {y} soon"
]
}
"{x} i am glad {y}" -> {
let switched = repersonalize (y)
[
"How have I helped you to be {y}"
"What makes you happy just now"
"Can you explain why you are suddenly {y}"
]
}
"{x} i am sad {y}" -> {
let switched = repersonalize (y)
[
"I am sorry to hear you are depressed"
"I'm sure it's not pleasant to be sad"
]
}
"{x} are like {y}" -> {
let switched_x = repersonalize (x)
let switched_y = repersonalize (y)
"What resemblance to you see between {switched_x} and {switched_y}"
}
"{x} is like {y}" -> {
let switched_x = repersonalize (x)
let switched_y = repersonalize (y)
[
"In what way is it that {switched_x} is like {switched_y}"
"What resemblance do you see"
"Could there really be some connection"
"How"
]
}
"{x} alike {y}" -> [
"In what way"
"What similarities are there"
]
"{x} same {y}" -> "What other connections do you see"
"{x} i was {y}" -> {
let switched = repersonalize (y)
[
"Were you really"
"Perhaps I already knew you were {switched}"
"Why do you tell me you were {switched} now"
]
}
"{x} was i {y}" -> {
let switched = repersonalize (y)
[
"What if you were {switched}"
"Do you think you were {switched}"
"What wouuld it mean if you were {switched}"
]
}
"{x} i am {y}" -> {
let switched = repersonalize (y)
[
"In what way are you {switched}"
"Do you want to be {switched}"
]
}
"{x} am i {y}" -> {
let switched = repersonalize (y)
[
"Do you believe you are {switched}"
"Would you want to be {switched}"
"You wish I would tell you you are {switched}"
"What would it mean if you were {switched}"
]
}
"{x} am {y}" -> [
"Why do you say *AM*"
"I don't understand that"
]
"{x} are you {y}" -> {
let switched = repersonalize (y)
[
"Why are you interested in whether I am {switched} or not"
"Would you prefer if I weren't {switched}"
"Perhaps I am {switched} in your fantasies"
]
}
"{x} you are {y}" -> {
let switched = repersonalize (y)
"What makes you think I am {y}"
}
"{x} because {y}" -> [
"Is that the real reason"
"What other reasons might there be"
"Does that reason seem to explain anything else"
]
"{x} were you {y}" -> {
let switched = repersonalize (y)
[
"Perhaps I was {switched}"
"What od you think"
"What if I had been {switched}"
]
}
"{x} i can't {y}" -> {
let switched = repersonalize (y)
[
"Maybe you could {switched} now"
"What if you could {switched}"
]
}
"{x} i feel {y}" -> {
let switched = repersonalize (y)
"Do you often feel {switched}"
}
"{x} i felt {y}" -> "What other feelings do you have"
"{x} i {y} you {z}" -> {
let switched = repersonalize (y)
"Perhaps in your fantasy we {switched} each other"
}
"{x} why don't you {y}" -> {
let switched = repersonalize (y)
[
"Should you {y} yourself"
"Do you believe I don't {y}"
"Perhaps I will {y} in good time"
]
}
"{x} yes {y}" -> [
"You seem quite positive"
"You are sure"
"I understand"
]
"{x} no {y}" -> [
"Why not"
"You are being a bit negative"
"Are you saying *NO* just to be negative"
]
"{x} someone {y}" -> "Can you be more specific"
"{x} everyone {y}" -> [
"Surely not everyone"
"Can you think of anyone in particular"
"Who for example"
"You are thinking of a special person"
]
"{x} always {y}" -> [
"Can you think of a specific example"
"When"
"What incident are you thinking of"
"Really--always"
]
"{x} what {y}" -> [
"Why do you ask"
"Does that question interest you"
"What is it you really want to know"
"What do you think"
"What comes to your mind when you ask that"
]
"{x} perhaps {y}" -> "You do not seem quite certain"
"{x} are {y}" -> {
let switched = repersonalize (y)
[
"Did you think they might not be {switched}"
"Possibly they are {switched}"
]
}
_ -> [
"Very interesting"
"I am not sure I understand you fully"
"What does that suggest to you"
"Please continue"
"Go on"
"Do you feel strongly about discussing such things"
]
}
print! (">>> ", do output > one_of > upcase)

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# A base library for Ludus
# Only loaded in the prelude
(defn bool [x] (if (= :^nil x) nil x))
(defn ludus/and [& args] (every? (map bool args)))
(defn ludus/or [& args] (some bool args))
(defn ludus/type [value]
(when (= :^nil value) (break :nil))
(def typed? (when (dictionary? value) (value :^type)))
(def the-type (if typed? typed? (type value)))
(case the-type
:buffer :string
:boolean :bool
:array :list
:table :dict
:cfunction :function
the-type))
(var stringify nil)
(defn- dict-str [dict]
(string/join
(map
(fn [[k v]] (string (stringify k) " " (stringify v)))
(pairs dict))
", "))
(defn- stringish? [x] (or (string? x) (buffer? x)))
(defn- stringify* [value]
(when (stringish? value) (break value))
(def type (ludus/type value))
(case type
:nil ""
:number (string value)
:bool (string value)
:keyword (string ":" value)
:tuple
(string/join (map stringify value) ", ")
:list
(string/join (map stringify value) ", ")
:dict (dict-str value)
:set
(string/join (map stringify (keys value)) ", ")
:box (stringify (value :^value))
:fn (string "fn " (value :name))
:function (string "builtin " (string value))
:pkg (dict-str value)
))
(set stringify stringify*)
(var show nil)
(defn- show-pkg [x]
(def tab (struct/to-table x))
(set (tab :^name) nil)
(set (tab :^type) nil)
(string "pkg " (x :^name) " {" (stringify tab) "}")
)
(defn- dict-show [dict]
(string/join
(map
(fn [[k v]] (string (show k) " " (show v)))
(pairs dict))
", "))
(defn- set-show [sett]
(def prepped (merge sett))
(set (prepped :^type) nil)
(def shown (map show (keys prepped)))
(string/join shown ", ")
)
(defn- show* [x]
(case (ludus/type x)
:nil "nil"
:string (string "\"" x "\"")
:tuple (string "(" (string/join (map show x) ", ") ")")
:list (string "[" (string/join (map show x) ", ") "]")
:dict (string "#{" (dict-show x) "}")
:set (string "${" (set-show x) "}")
:box (string "box " (x :name) " [ " (show (x :^value)) " ]")
:pkg (show-pkg x)
(stringify x)))
(set show show*)
# (var json nil)
# (defn- dict-json [dict]
# (string/join
# (map
# (fn [[k v]] (string (json k) ": " (json v)))
# (pairs dict))
# ", "))
# (defn- json* [x]
# (case (ludus/type x)
# :nil "\"null\""
# :number (string x)
# :bool (if true "\"true\"" "\"false\"")
# :string (string "\"" x "\"")
# :keyword (string "\"" x "\"")
# :tuple (string "[" (string/join (map json x) ", ") "]")
# :list (string "[" (string/join (map json x) ", ")"]")
# :dict (string "{" (dict-json x) "}")
# :set (string "[" (string/join (map json (keys x)) ", ") "]")
# (show x)))
# (set json json*)
(defn show-patt [x]
(case (x :type)
:nil "nil"
:bool (string (x :data))
:number (string (x :data))
:keyword (string ":" (x :data))
:word (x :data)
:placeholder (get-in x [:token :lexeme])
:tuple (string "(" (string/join (map show-patt (x :data)) ", ") ")")
:list (string "[" (string/join (map show-patt (x :data)) ", ")"]")
:dict (string "#{" (string/join (map show-patt (x :data)) ", ") "}")
:pair (string (show-patt (get-in x [:data 0])) " " (show-patt (get-in x [:data 1])))
:typed (string (show-patt (get-in x [:data 1])) " as " (show-patt (get-in x [:data 0])))
:interpolated (get-in x [:token :lexeme])
:string (get-in x [:token :lexeme])
:splat (string "..." (when (x :data) (show-patt (x :data))))
(error (string "cannot show pattern of unknown type " (x :type)))))
(defn pretty-patterns [fnn]
(def {:body clauses} fnn)
(string/join (map (fn [x] (-> x first show-patt)) clauses) "\n"))
(defn doc [fnn]
(when (not= :fn (ludus/type fnn)) (break "No documentation available."))
(def {:name name :doc docstring} fnn)
(string/join [name
(pretty-patterns fnn)
(if docstring docstring "No docstring available.")]
"\n"))
(defn- conj!-set [sett value]
(set (sett value) true)
sett)
(defn- conj-set [sett value]
(def new (merge sett))
(conj!-set new value))
(defn- conj!-list [list value]
(array/push list value))
(defn- conj-list [list value]
(def new (array/slice list))
(conj!-list new value))
(defn conj! [x value]
(case (ludus/type x)
:list (conj!-list x value)
:set (conj!-set x value)))
(defn conj [x value]
(case (ludus/type x)
:list (conj-list x value)
:set (conj-set x value)
(error (string "cannot conj onto " (show x)))))
(defn disj! [sett value]
(set (sett value) nil)
sett)
(defn disj [sett value]
(def new (merge sett))
(set (new value) nil)
new)
(defn assoc! [dict key value]
(set (dict key) value)
dict)
(defn assoc [dict key value]
(merge dict {key value}))
(defn dissoc! [dict key]
(set (dict key) nil)
dict)
(defn dissoc [dict key]
(def new (merge dict))
(set (new key) nil)
new)
(defn ludus/get [key dict &opt def]
(default def :^nil)
(get dict key def))
(defn rest [indexed]
(array/slice indexed 1))
(defn to_list [x]
(case (ludus/type x)
:list x
:tuple @[;x]
:dict (pairs x)
:set (-> x (dissoc :^type) keys)
@[x]))
(defn showprint [x]
(if (= :string (ludus/type x))
x
(show x)))
(defn print! [args]
(print ;(map showprint args)))
(defn prn [x]
(pp x)
x)
(defn concat [x y & zs]
(case (ludus/type x)
:string (string x y ;zs)
:list (array/concat @[] x y ;zs)
:set (merge x y ;zs)))
(defn unbox [b] (get b :^value))
(defn store! [b x] (set (b :^value) x))
(defn mod [x y]
(% x y))
(defn- byte->ascii [c i]
(if (< c 128)
(string/from-bytes c)
(error (string "non-ASCII character at index" i))))
(defn chars [str]
(def out @[])
(try
(for i 0 (length str)
(array/push out (byte->ascii (str i) i)))
([e] (break [:err e])))
[:ok out])
(def ctx {
"add" +
"and" ludus/and
"assoc!" assoc!
"assoc" assoc
"atan_2" math/atan2
"bool" bool
"ceil" math/ceil
"chars" chars
"concat" concat
"conj!" conj!
"conj" conj
"cos" math/cos
"count" length
"dec" dec
"disj!" disj!
"disj" disj
"dissoc!" dissoc!
"dissoc" dissoc
"div" /
"doc" doc
"downcase" string/ascii-lower
"eq?" deep=
"first" first
"floor" math/floor
"get" ludus/get
"gt" >
"gte" >=
"inc" inc
"last" last
"lt" <
"lte" <=
"mod" mod
"mult" *
"not" not
"nth" ludus/get
"or" ludus/or
"pi" math/pi
"print!" print!
"prn" prn
"push" array/push
"random" math/random
"range" range
"rest" rest
"round" math/round
"show" show
"sin" math/sin
"slice" array/slice
"split" string/split
"sqrt" math/sqrt
"store!" store!
"str_slice" string/slice
"stringify" stringify
"sub" -
"tan" math/tan
"to_list" to_list
"trim" string/trim
"triml" string/triml
"trimr" string/trimr
"type" ludus/type
"unbox" unbox
"upcase" string/ascii-upper
})
(def base (let [b @{:^type :dict}]
(each [k v] (pairs ctx)
(set (b (keyword k)) v))
b))

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(import /src/base :as base)
(import /src/prelude :as prelude)
(defn map-values [f dict]
(from-pairs (map (fn [[k v]] [k (f v)]) (pairs dict))))
(def with-docs (map-values base/doc prelude/ctx))
(def sorted-names (-> with-docs keys sort))
(defn escape-underscores [str] (string/replace "_" "\\_" str))
(defn escape-punctuation [str] (->> str
(string/replace "?" "")
(string/replace "!" "")))
(defn toc-entry [name]
(def escaped (escape-underscores name))
(string "[" escaped "](#" (escape-punctuation escaped) ")"))
(def alphabetical-list
(string/join (map toc-entry sorted-names) "&nbsp;&nbsp;&nbsp; "))
(def topics {
"math" ["abs" "add" "angle" "atan/2" "between?" "ceil" "cos" "dec" "deg/rad" "deg/turn" "dist" "div" "div/0" "div/safe" "even?" "floor" "gt?" "gte?" "heading/vector" "inc" "inv" "inv/0" "inv/safe" "lt?" "lte?" "max" "min" "mod" "mod/0" "mod/safe" "mult" "neg" "neg?" "odd?" "pi" "pos?" "rad/deg" "rad/turn" "random" "random_int" "range" "round" "sin" "sqrt" "sqrt/safe" "square" "sub" "sum_of_squares" "tan" "tau" "turn/deg" "turn/rad" "zero?"]
"boolean" ["and" "bool" "bool?" "false?" "not" "or" "true?"]
"dicts" ["any?" "assoc" "assoc?" "coll?" "count" "dict" "dict?" "diff" "dissoc" "empty?" "get" "keys" "random" "update" "values"]
"lists" ["any?" "append" "at" "butlast" "coll?" "concat" "count" "each!" "empty?" "filter" "first" "fold" "join" "keep" "last" "list" "list?" "map" "ordered?" "random" "range" "rest" "second" "sentence" "slice"]
"sets" ["any?" "append" "coll?" "concat" "contains?" "count" "empty?" "omit" "random" "set" "set?"]
"tuples" ["any?" "at" "coll?" "count" "empty?" "first" "last" "ordered?" "rest" "second" "tuple?"]
"strings" ["any?" "chars" "chars/safe" "concat" "count" "downcase" "empty?" "join" "sentence" "show" "slice" "split" "string" "string?" "strip" "trim" "upcase" "words"]
"types and values" ["assoc?" "bool?" "box?" "coll?" "dict?" "eq?" "fn?" "keyword?" "list?" "neq?" "nil?" "number?" "ordered?" "set?" "show" "some" "some?" "string?" "tuple?" "type"]
"boxes and state" ["box?" "unbox" "store!" "update!"]
"results" ["err" "err?" "ok" "ok?" "unwrap!" "unwrap_or"]
"errors" ["assert!"]
"turtle graphics" ["back!" "background!" "bk!" "clear!" "colors" "fd!" "forward!" "goto!" "heading" "heading/vector" "home!" "left!" "lt!" "pc!" "pd!" "pencolor" "pencolor!" "pendown!" "pendown?" "penup!" "penwidth" "penwidth!" "position" "pu!" "pw!" "render_turtle!" "reset_turtle!" "right!" "rt!" "turtle_state"]
"environment and i/o" ["doc!" "print!" "report!" "state"]
})
(defn capitalize [str]
(def fst (slice str 0 1))
(def rest (slice str 1))
(def init_cap (string/ascii-upper fst))
(def lower_rest (string/ascii-lower rest))
(string init_cap lower_rest))
(defn topic-entry [topic]
(string "### " (capitalize topic) "\n"
(as-> topic _ (topics _) (array/slice _) (sort _) (map toc-entry _)
(string/join _ "&nbsp;&nbsp;&nbsp; "))
"\n"))
(def by-topic (let [the-topics (-> topics keys sort)
topics-entries (map topic-entry the-topics)]
(string/join topics-entries "\n")))
(defn compose-entry [name]
(def header (string "\n### " name "\n"))
(def the-doc (get with-docs name))
(when (= "No documentation available." the-doc)
(break (string header the-doc "\n")))
(def lines (string/split "\n" the-doc))
(def description (last lines))
(def patterns (string/join (slice lines 1 (-> lines length dec)) "\n"))
(def backto "[Back to top.](#ludus-prelude-documentation)\n")
(string header description "\n```\n" patterns "\n```\n" backto))
(compose-entry "update")
(def entries (string/join (map compose-entry sorted-names) "\n---"))
(def doc-file (string
```
# Ludus prelude documentation
These functions are available in every Ludus script.
The documentation for any function can be found within Ludus by passing the function to `doc!`,
e.g., running `doc! (add)` will send the documentation for `add` to the console.
For more information on the syntax & semantics of the Ludus language, see [language.md](./language.md).
The prelude itself is just a Ludus file, which you can see at [prelude.ld](./prelude.ld).
## A few notes
**Naming conventions.** Functions whose name ends with a question mark, e.g., `eq?`, return booleans.
Functions whose name ends with an exclamation point, e.g., `make!`, change state in some way.
In other words, they _do things_ rather than _calculating values_.
Functions whose name includes a slash either convert from one value to another, e.g. `deg/rad`,
or they are variations on a function, e.g. `div/0` as a variation on `div`.
**How entries are formatted.** Each entry has a brief (sometimes too brief!) description of what it does.
It is followed by the patterns for each of its function clauses.
This should be enough to indicate order of arguments, types, and so on.
**Patterns often, but do not always, indicate types.** Typed patterns are written as `foo as :bar`,
where the type is indicated by the keyword.
Possible ludus types are: `:nil`, `:boolean`, `:number`, `:keyword` (atomic values);
`:string` (strings are their own beast); `:tuple` and `:list` (ordered collections), `:set`s, and `:dict`ionaries (the other collection types); `:pkg` (packages, which are quasi-collections); `:fn` (functions); and `:box`es.
**Conventional types.** Ludus has two types based on conventions.
* _Result tuples._ Results are a way of modeling the result of a calculation that might fail.
The two possible values are `(:ok, value)` and `(:err, msg)`.
`msg` is usually a string describing what went wrong.
To work with result tuples, see [`unwrap!`](#unwrap) and [`unwrap_or`](#unwrap_or).
That said, usually you work with these using pattern matching.
* _Vectors._ Vectors are 2-element tuples of x and y coordinates.
The origin is `(0, 0)`.
Many math functions take vectors as well as numbers, e.g., `add` and `mult`.
You will see vectors indicated in patterns by an `(x, y)` tuple.
You can see what this looks like in the last clause of `add`: `((x1, y1), (x2, y2))`.
## Functions by topic
```
by-topic
```
## All functions, alphabetically
```
alphabetical-list
```
## Function documentation
```
entries
))
(spit "prelude.md" doc-file)

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src/errors.janet
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(import /src/base :as b)
(defn- get-line [source line]
((string/split "\n" source) (dec line)))
(defn- caret [source line start]
(def lines (string/split "\n" source))
(def the-line (lines (dec line)))
(def prev-lines (slice lines 0 (dec line)))
(def char-counts (map (fn [x] (-> x length inc)) prev-lines))
(def prev-line-chars (sum char-counts))
(def offset (- start prev-line-chars))
(def indent (string/repeat "." (+ 6 offset)))
(string indent "^")
)
(defn scan-error [e]
(def {:line line-num :input input :source source :start start :msg msg} e)
(print "Syntax error: " msg)
(print " on line " line-num " in " input ":")
(def source-line (get-line source line-num))
(print " >>> " source-line)
(print (caret source line-num start))
e)
(defn parse-error [e]
(def msg (e :msg))
(def {:line line-num :input input :source source :start start} (e :token))
(def source-line (get-line source line-num))
(print "Syntax error: " msg)
(print " on line " line-num " in " input ":")
(print " >>> " source-line)
(print (caret source line-num start))
e)
(defn validation-error [e]
(def msg (e :msg))
(def {:line line-num :input input :source source :start start} (get-in e [:node :token]))
(def source-line (get-line source line-num))
(case msg
"unbound name"
(do
(print "Validation error: " msg " " (get-in e [:node :data]))
(print " on line " line-num " in " input ":")
(print " >>> " source-line)
(print (caret source line-num start)))
(do
(print "Validation error: " msg)
(print " on line " line-num " in " input ":")
(print " >>> " source-line)
(print (caret source line-num start))))
e)
(defn- fn-no-match [e]
(print "Ludus panicked! no match")
(def {:line line-num :source source :input input :start start} (get-in e [:node :token]))
(def source-line (get-line source line-num))
(print " on line " line-num " in " input ", ")
(def called (e :called))
(print " calling: " (slice (b/show called) 3))
(def value (e :value))
(print " with arguments: " (b/show value))
(print " expected match with one of:")
(def patterns (b/pretty-patterns called))
(def fmt-patt (do
(def lines (string/split "\n" patterns))
(def indented (map (fn [x] (string " " x)) lines))
(string/join indented "\n")
))
(print fmt-patt)
(print " >>> " source-line)
(print (caret source line-num start))
)
(defn- let-no-match [e]
(print "Ludus panicked! no match")
(def {:line line-num :source source :input input :start start} (get-in e [:node :token]))
(def source-line (get-line source line-num))
(print " on line " line-num " in " input ", ")
(print " matching: " (b/show (e :value)))
(def pattern (get-in e [:node :data 0]))
(print " with pattern: " (b/show-patt pattern))
(print " >>> " source-line)
(print (caret source line-num start))
e)
(defn- match-no-match [e]
(print "Ludus panicked! no match")
(def {:line line-num :source source :input input :start start} (get-in e [:node :token]))
(print " on line " line-num " in " input ", ")
(def value (e :value))
(print " matching: " (b/show value))
(print " with patterns:")
(def clauses (get-in e [:node :data 1]))
(def patterns (b/pretty-patterns {:body clauses}))
(def fmt-patt (do
(def lines (string/split "\n" patterns))
(def indented (map (fn [x] (string " " x)) lines))
(string/join indented "\n")
))
(print fmt-patt)
(def source-line (get-line source line-num))
(print " >>> " source-line)
(print (caret source line-num start))
e)
(defn- generic-panic [e]
(def msg (e :msg))
(def {:line line-num :source source :input input :start start} (get-in e [:node :token]))
(def source-line (get-line source line-num))
(print "Ludus panicked! " msg)
(print " on line " line-num " in " input ":")
(print " >>> " source-line)
(print (caret source line-num start))
e)
(defn- unbound-name [e]
(def {:line line-num :source source :lexeme name :input input :start start} (get-in e [:node :token]))
(def source-line (get-line source line-num))
(print "Ludus panicked! unbound name " name)
(print " on line " line-num " in " input ":")
(print " >>> " source-line)
(print (caret source line-num start))
e)
(defn runtime-error [e]
(when (= :string (type e))
(print (string "Internal Ludus error: " e))
(print "Please file an issue at https://alea.ludus.dev/twc/ludus/issues")
(break e))
(def msg (e :msg))
(case msg
"no match: function call" (fn-no-match e)
"no match: let binding" (let-no-match e)
"no match: match form" (match-no-match e)
"no match: when form" (generic-panic e)
"unbound name" (unbound-name e)
(generic-panic e))
e)

657
src/interpreter.janet
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@ -1,657 +0,0 @@
# A tree walk interpreter for ludus
(import /src/base :as b)
(var interpret nil)
(var match-pattern nil)
(defn- todo [msg] (error (string "not yet implemented: " msg)))
(defn- resolve-name [name ctx]
# # (print "resolving " name " in:")
# # (pp ctx)
(when (not ctx) (break :^not-found))
(if (has-key? ctx name)
(ctx name)
(resolve-name name (ctx :^parent))))
(defn- match-word [word value ctx]
(def name (word :data))
# # (print "matched " (b/show value) " to " name)
(set (ctx name) value)
{:success true :ctx ctx})
(defn- typed [pattern value ctx]
(def [type-ast word] (pattern :data))
(def type (type-ast :data))
(if (= type (b/ludus/type value))
(match-word word value ctx)
{:success false :miss [pattern value]}))
(defn- match-tuple [pattern value ctx]
(when (not (tuple? value))
(break {:success false :miss [pattern value]}))
(def val-len (length value))
(var members (pattern :data))
(when (empty? members)
(break (if (empty? value)
{:success true :ctx ctx}
{:success false :miss [pattern value]})))
(def patt-len (length members))
(var splat nil)
(def splat? (= :splat ((last members) :type)))
(when splat?
(when (< val-len patt-len)
# (print "mismatched splatted tuple lengths")
(break {:success false :miss [pattern value]}))
# (print "splat!")
(set splat (last members))
(set members (slice members 0 (dec patt-len))))
(when (and (not splat?) (not= val-len patt-len))
# (print "mismatched tuple lengths")
(break {:success false :miss [pattern value]}))
(var curr-mem :^nothing)
(var curr-val :^nothing)
(var success true)
(for i 0 (length members)
(set curr-mem (get members i))
(set curr-val (get value i))
# (print "in tuple, matching " curr-val " with ")
# (pp curr-mem)
(def match? (match-pattern curr-mem curr-val ctx))
# (pp match?)
(when (not (match? :success))
(set success false)
(break)))
(when (and splat? (splat :data))
(def rest (array/slice value (length members)))
(match-word (splat :data) rest ctx))
(if success
{:success true :ctx ctx}
{:success false :miss [pattern value]}))
(defn- match-list [pattern value ctx]
(when (not (array? value))
(break {:success false :miss [pattern value]}))
(def val-len (length value))
(var members (pattern :data))
(when (empty? members)
(break (if (empty? value)
{:success true :ctx ctx}
{:success false :miss [pattern value]})))
(def patt-len (length members))
(var splat nil)
(def splat? (= :splat ((last members) :type)))
(when splat?
(when (< val-len patt-len)
# (print "mismatched splatted list lengths")
(break {:success false :miss [pattern value]}))
# (print "splat!")
(set splat (last members))
(set members (slice members 0 (dec patt-len))))
(when (and (not splat?) (not= val-len patt-len))
# (print "mismatched list lengths")
(break {:success false :miss [pattern value]}))
(var curr-mem :^nothing)
(var curr-val :^nothing)
(var success true)
(for i 0 (length members)
(set curr-mem (get members i))
(set curr-val (get value i))
# (print "in list, matching " curr-val " with ")
# (pp curr-mem)
(def match? (match-pattern curr-mem curr-val ctx))
# (pp match?)
(when (not (match? :success))
(set success false)
(break)))
(when (and splat? (splat :data))
(def rest (array/slice value (length members)))
(match-word (splat :data) rest ctx))
(if success
{:success true :ctx ctx}
{:success false :miss [pattern value]}))
(defn- match-string [pattern value ctx]
(when (not (string? value))
(break {:success false :miss [pattern value]}))
(def {:compiled compiled :bindings bindings} pattern)
# (print "matching " value " with")
# (pp (pattern :grammar))
(def matches (peg/match compiled value))
(when (not matches)
(break {:success false :miss [pattern value]}))
(when (not= (length matches) (length bindings))
(error "oops: different number of matches and bindings"))
(for i 0 (length matches)
(set (ctx (bindings i)) (matches i)))
{:success true :ctx ctx})
(defn- match-dict [pattern value ctx]
(when (not (table? value))
(break {:success false :miss [pattern value]}))
(def val-size (length value))
(var members (pattern :data))
(def patt-len (length members))
(when (empty? members)
(break (if (empty? value)
{:success true :ctx ctx}
{:success false :miss [pattern value]})))
(var splat nil)
(def splat? (= :splat ((last members) :type)))
(when splat?
(when (< val-size patt-len)
# (print "mismatched splatted dict lengths")
(break {:success false :miss [pattern value]}))
# (print "splat!")
(set splat (last members))
(set members (slice members 0 (dec patt-len))))
(when (and (not splat?) (not= val-size patt-len))
# (print "mismatched dict lengths")
(break {:success false :miss [pattern value]}))
(var success true)
(def matched-keys @[])
(for i 0 (length members)
(def curr-pair (get members i))
(def [curr-key curr-patt] (curr-pair :data))
(def key (interpret curr-key ctx))
(def curr-val (value key))
(def match? (match-pattern curr-patt curr-val ctx))
(array/push matched-keys key)
(when (not (match? :success))
(set success false)
(break)))
(when (and splat? (splat :data) success)
(def rest (merge value))
(each key matched-keys
(set (rest key) nil))
(match-word (splat :data) rest ctx))
(if success
{:success true :ctx ctx}
{:success false :miss [pattern value]}))
(defn- match-pattern* [pattern value &opt ctx]
# (print "in match-pattern, matching " value " with:")
# (pp pattern)
(default ctx @{})
(def data (pattern :data))
(case (pattern :type)
# always match
:placeholder {:success true :ctx ctx}
:ignored {:success true :ctx ctx}
:word (match-word pattern value ctx)
# match on equality
:nil {:success (= :^nil value) :ctx ctx}
:bool {:success (= data value) :ctx ctx}
:number {:success (= data value) :ctx ctx}
:string {:success (= data value) :ctx ctx}
:keyword {:success (= data value) :ctx ctx}
# TODO: lists, dicts
:tuple (match-tuple pattern value ctx)
:list (match-list pattern value ctx)
:dict (match-dict pattern value ctx)
:interpolated (match-string pattern value ctx)
:typed (typed pattern value ctx)
))
(set match-pattern match-pattern*)
(defn- lett [ast ctx]
# (print "lett!")
# (pp ast)
(def [patt expr] (ast :data))
(def value (interpret expr ctx))
(def match? (match-pattern patt value))
(if (match? :success)
(do
(merge-into ctx (match? :ctx))
value)
(error {:node ast :value value :msg "no match: let binding"})))
(defn- matchh [ast ctx]
(def [to-match clauses] (ast :data))
(def value (interpret to-match ctx))
(def len (length clauses))
(when (ast :match) (break ((ast :match) 0 value ctx)))
(defn match-fn [i value ctx]
(when (= len i)
(error {:node ast :value value :msg "no match: match form"}))
(def clause (clauses i))
(def [patt guard expr] clause)
(def match? (match-pattern patt value @{:^parent ctx}))
(when (not (match? :success))
(break (match-fn (inc i) value ctx)))
(def body-ctx (match? :ctx))
(def guard? (if guard
(b/bool (interpret guard body-ctx)) true))
(when (not guard?)
(break (match-fn (inc i) value ctx)))
(interpret expr body-ctx))
(set (ast :match) match-fn)
(match-fn 0 value ctx))
(defn- script [ast ctx]
(def lines (ast :data))
(def last-line (last lines))
(for i 0 (-> lines length dec)
(interpret (lines i) ctx))
(interpret last-line ctx))
(defn- block [ast parent]
(def lines (ast :data))
(def last-line (last lines))
(def ctx @{:^parent parent})
(for i 0 (-> lines length dec)
(interpret (lines i) ctx))
(interpret last-line ctx))
(defn- to_string [ctx] (fn [x]
(if (buffer? x)
(string x)
(b/stringify (interpret x ctx)))))
(defn- interpolated [ast ctx]
(def terms (ast :data))
(def interpolations (map (to_string ctx) terms))
(string/join interpolations))
(defn- iff [ast ctx]
(def [condition then else] (ast :data))
(if (b/bool (interpret condition ctx))
(interpret then ctx)
(interpret else ctx)))
# TODO: use a tail call here
(defn- whenn [ast ctx]
(def clauses (ast :data))
(var result :^nothing)
(each clause clauses
(def [lhs rhs] clause)
(when (b/bool (interpret lhs ctx))
(set result (interpret rhs ctx))
(break)))
(when (= result :^nothing)
(error {:node ast :msg "no match: when form"}))
result)
(defn- word [ast ctx]
(def resolved (resolve-name (ast :data) ctx))
(if (= :^not-found resolved)
(error {:node ast :msg "unbound name"})
resolved))
(defn- tup [ast ctx]
(def members (ast :data))
(def the-tup @[])
(each member members
(array/push the-tup (interpret member ctx)))
[;the-tup])
(defn- args [ast ctx]
(def members (ast :data))
(def the-args @[])
(each member members
(array/push the-args (interpret member ctx)))
(if (ast :partial)
{:^type :partial :args the-args}
[;the-args]))
(defn- sett [ast ctx]
(def members (ast :data))
(def the-set @{:^type :set})
(each member members
(def value (interpret member ctx))
(set (the-set value) true))
the-set)
(defn- list [ast ctx]
(def members (ast :data))
(def the-list @[])
(each member members
(if (= :splat (member :type))
(do
(def splatted (interpret (member :data) ctx))
(when (not= :array (type splatted))
(error {:node member :msg "cannot splat non-list into list"}))
(array/concat the-list splatted))
(array/push the-list (interpret member ctx))))
the-list)
(defn- dict [ast ctx]
(def members (ast :data))
(def the-dict @{})
(each member members
(if (= :splat (member :type))
(do
(def splatted (interpret (member :data) ctx))
(when (or
(not= :table (type splatted))
(:^type splatted))
(error {:node member :msg "cannot splat non-dict into dict"}))
(merge-into the-dict splatted))
(do
(def [key-ast value-ast] (member :data))
# (print "dict key")
# (pp key-ast)
# (print "dict value")
# (pp value-ast)
(def key (interpret key-ast ctx))
(def value (interpret value-ast ctx))
(set (the-dict key) value))))
the-dict)
(defn- box [ast ctx]
(def {:data value-ast :name name} ast)
(def value (interpret value-ast ctx))
(def box @{:^type :box :^value value :name name})
(set (ctx name) box)
box)
(defn- repeatt [ast ctx]
(def [times-ast body] (ast :data))
(def times (interpret times-ast ctx))
(when (not (number? times))
(error {:node times-ast :msg (string "repeat needs a `number` of times; you gave me a " (type times))}))
(repeat times (interpret body ctx)))
(defn- panic [ast ctx]
(def info (interpret (ast :data) ctx))
(error {:node ast :msg info}))
# TODO: add docstrings & pattern docs to fns
# Depends on: good string representation of patterns
# For now, this should be enough to tall the thing
(defn- fnn [ast ctx]
(def {:name name :data clauses :doc doc} ast)
# (print "defining fn " name)
(def closure (merge ctx))
(def the-fn @{:name name :^type :fn :body clauses :ctx closure :doc doc})
(when (not= :^not-found (resolve-name name ctx))
# (print "fn "name" was forward declared")
(def fwd (resolve-name name ctx))
(set (fwd :body) clauses)
(set (fwd :ctx) closure)
(set (fwd :doc) doc)
# (print "fn " name " has been defined")
# (pp fwd)
(break fwd))
# (pp the-fn)
(set (closure name) the-fn)
(set (ctx name) the-fn)
the-fn)
(defn- is_placeholder [x] (= x :_))
(var call-fn nil)
(defn- partial [root-ast the-fn partial-args]
(when (the-fn :applied)
(error {:msg "cannot partially apply a partially applied function"
:node root-ast :called the-fn :args partial-args}))
# (print "calling partially applied function")
(def args (partial-args :args))
# (pp args)
(def pos (find-index is_placeholder args))
(def name (string (the-fn :name) " *partial*"))
(defn partial-fn [root-ast missing]
# (print "calling function with arg " (b/show missing))
# (pp partial-args)
(def full-args (array/slice args))
(set (full-args pos) missing)
# (print "all args: " (b/show full-args))
(call-fn root-ast the-fn [;full-args]))
{:^type :fn :applied true :name name :body partial-fn})
(defn- call-fn* [root-ast the-fn args]
# (print "on line " (get-in root-ast [:token :line]))
# (print "calling " (b/show the-fn))
# (print "with args " (b/show args))
# (pp args)
(when (or
(= :function (type the-fn))
(= :cfunction (type the-fn)))
# (print "Janet function")
(break (the-fn ;args)))
(def clauses (the-fn :body))
(when (= :nothing clauses)
(error {:node root-ast :called the-fn :value args :msg "cannot call function before it is defined"}))
(when (= :function (type clauses))
(break (clauses root-ast ;args)))
(def len (length clauses))
(when (the-fn :match) (break ((the-fn :match) root-ast 0 args)))
(defn match-fn [root-ast i args]
(when (= len i)
(error {:node root-ast :called the-fn :value args :msg "no match: function call"}))
(def clause (clauses i))
(def [patt guard expr] clause)
(def match?
(match-pattern patt args @{:^parent (the-fn :ctx)}))
(when (not (match? :success))
(break (match-fn root-ast (inc i) args)))
# (print "matched!")
(def body-ctx (match? :ctx))
(def guard? (if guard
(b/bool (interpret guard body-ctx)) true))
# (print "passed guard")
(when (not guard?)
(break (match-fn root-ast (inc i) args)))
(interpret expr body-ctx))
(set (the-fn :match) match-fn)
(match-fn root-ast 0 args))
(set call-fn call-fn*)
(defn- call-partial [root-ast the-fn arg] ((the-fn :body) root-ast ;arg))
(defn- apply-synth-term [root-ast prev curr]
# (print "applying " (b/show prev))
# (print "to" (b/show curr))
(def types [(b/ludus/type prev) (b/ludus/type curr)])
# (print "typle:")
# (pp types)
(match types
[:fn :tuple] (call-fn root-ast prev curr)
[:fn :partial] (partial root-ast prev curr)
[:function :tuple] (call-fn root-ast prev curr)
# [:applied :tuple] (call-partial root-ast prev curr)
[:keyword :args] (get (first curr) prev :^nil)
[:keyword :tuple] (get (first curr) prev :^nil)
[:dict :keyword] (get prev curr :^nil)
[:nil :keyword] :^nil
[:pkg :keyword] (get prev curr :^nil)
[:pkg :pkg-kw] (get prev curr :^nil)
(error (string "cannot call " (b/ludus/type prev) " `" (b/show prev) "`"))))
(defn- synthetic [ast ctx]
(def terms (ast :data))
# (print "interpreting synthetic")
# (pp ast)
# (pp terms)
(def first-term (first terms))
(def last-term (last terms))
(var prev (interpret first-term ctx))
# (print "root term: ")
# (pp prev)
(for i 1 (-> terms length dec)
(def curr (interpret (terms i) ctx))
# (print "term " i ": " curr)
(set prev (apply-synth-term first-term prev curr)))
# (print "done with inner terms, applying last term")
(apply-synth-term first-term prev (interpret last-term ctx)))
(defn- doo [ast ctx]
(def terms (ast :data))
(var prev (interpret (first terms) ctx))
(def last-term (last terms))
(for i 1 (-> terms length dec)
(def curr (interpret (terms i) ctx))
(set prev (apply-synth-term (first terms) curr [prev])))
(def last-fn (interpret last-term ctx))
(apply-synth-term (first terms) last-fn [prev]))
(defn- pkg [ast ctx]
(def members (ast :data))
(def the-pkg @{:^name (ast :name) :^type :pkg})
(each member members
(def [key-ast value-ast] (member :data))
(def key (interpret key-ast ctx))
(def value (interpret value-ast ctx))
(set (the-pkg key) value))
# (pp the-pkg)
(def out (table/to-struct the-pkg))
(set (ctx (ast :name)) out)
out)
(defn- loopp [ast ctx]
# (print "looping!")
(def data (ast :data))
(def args (interpret (data 0) ctx))
# this doesn't work: context persists between different interpretations
# we want functions to work this way, but not loops (I think)
# (when (ast :match) (break ((ast :match) 0 args)))
(def clauses (data 1))
(def len (length clauses))
(var loop-ctx @{:^parent ctx})
(defn match-fn [i args]
(when (= len i)
(error {:node ast :value args :msg "no match: loop"}))
(def clause (clauses i))
(def [patt guard expr] clause)
(def match?
(match-pattern patt args loop-ctx))
(when (not (match? :success))
# (print "no match")
(break (match-fn (inc i) args)))
# (print "matched!")
(def body-ctx (match? :ctx))
(def guard? (if guard
(b/bool (interpret guard body-ctx)) true))
# (print "passed guard")
(when (not guard?)
(break (match-fn (inc i) args)))
(interpret expr body-ctx))
(set (ast :match) match-fn)
(set (loop-ctx :^recur) match-fn)
# (print "ATTACHED MATCH-FN")
(match-fn 0 args))
(defn- recur [ast ctx]
# (print "recurring!")
(def passed (ast :data))
(def args (interpret passed ctx))
(def match-fn (resolve-name :^recur ctx))
# (print "match fn in ctx:")
# (pp (ctx :^recur))
# (pp match-fn)
# (pp ctx)
(match-fn 0 args))
# TODO for 0.1.0
(defn- testt [ast ctx] (todo "test"))
(defn- ns [ast ctx] (todo "nses"))
(defn- importt [ast ctx] (todo "imports"))
(defn- withh [ast ctx] (todo "with"))
(defn- usee [ast ctx] (todo "use"))
(defn- interpret* [ast ctx]
# (print "interpreting node " (ast :type))
(case (ast :type)
# literals
:nil :^nil
:number (ast :data)
:bool (ast :data)
:string (ast :data)
:keyword (ast :data)
:placeholder :_
# collections
:tuple (tup ast ctx)
:args (args ast ctx)
:list (list ast ctx)
:set (sett ast ctx)
:dict (dict ast ctx)
# composite forms
:if (iff ast ctx)
:block (block ast ctx)
:when (whenn ast ctx)
:script (script ast ctx)
:panic (panic ast ctx)
# looping forms
:loop (loopp ast ctx)
:recur (recur ast ctx)
:repeat (repeatt ast ctx)
# named/naming forms
:word (word ast ctx)
:interpolated (interpolated ast ctx)
:box (box ast ctx)
:pkg (pkg ast ctx)
:pkg-name (word ast ctx)
# patterned forms
:let (lett ast ctx)
:match (matchh ast ctx)
# functions
:fn (fnn ast ctx)
# synthetic
:synthetic (synthetic ast ctx)
# do
:do (doo ast ctx)
# deferred until after computer class
# :with (withh ast ctx)
# :import (importt ast ctx)
# :ns (ns ast ctx)
# :use (usee ast ctx)
# :test (testt ast ctx)
))
(set interpret interpret*)
# # repl
# (import /src/scanner :as s)
# (import /src/parser :as p)
# (import /src/validate :as v)
# (var source nil)
# (defn- has-errors? [{:errors errors}] (and errors (not (empty? errors))))
# (defn run []
# (def scanned (s/scan source))
# (when (has-errors? scanned) (break (scanned :errors)))
# (def parsed (p/parse scanned))
# (when (has-errors? parsed) (break (parsed :errors)))
# (def validated (v/valid parsed b/ctx))
# # (when (has-errors? validated) (break (validated :errors)))
# # (def cleaned (get-in parsed [:ast :data 1]))
# # # (pp cleaned)
# (interpret (parsed :ast) @{:^parent b/lett})
# # (try (interpret (parsed :ast) @{:^parent b/ctx})
# # ([e] (if (struct? e) (error (e :msg)) (error e))))
# )
# # (do
# (comment
# (set source `
# let foo = 42
# "{foo} bar baz"
# `)
# (def result (run))
# )

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# pulled from cfiggers/jayson
(defmacro- letv [bindings & body]
~(do ,;(seq [[k v] :in (partition 2 bindings)] ['var k v]) ,;body))
(defn- read-hex [n]
(scan-number (string "0x" n)))
(defn- check-utf-16 [capture]
(let [u (read-hex capture)]
(if (and (>= u 0xD800)
(<= u 0xDBFF))
capture
false)))
(def- utf-8->bytes
(peg/compile
~{:double-u-esc (/ (* "\\u" (cmt (<- 4) ,|(check-utf-16 $)) "\\u" (<- 4))
,|(+ (blshift (- (read-hex $0) 0xD800) 10)
(- (read-hex $1) 0xDC00) 0x10000))
:single-u-esc (/ (* "\\u" (<- 4)) ,|(read-hex $))
:unicode-esc (/ (+ :double-u-esc :single-u-esc)
,|(string/from-bytes
;(cond
(<= $ 0x7f) [$]
(<= $ 0x7ff)
[(bor (band (brshift $ 6) 0x1F) 0xC0)
(bor (band (brshift $ 0) 0x3F) 0x80)]
(<= $ 0xffff)
[(bor (band (brshift $ 12) 0x0F) 0xE0)
(bor (band (brshift $ 6) 0x3F) 0x80)
(bor (band (brshift $ 0) 0x3F) 0x80)]
# Otherwise
[(bor (band (brshift $ 18) 0x07) 0xF0)
(bor (band (brshift $ 12) 0x3F) 0x80)
(bor (band (brshift $ 6) 0x3F) 0x80)
(bor (band (brshift $ 0) 0x3F) 0x80)])))
:escape (/ (* "\\" (<- (set "avbnfrt\"\\/")))
,|(get {"a" "\a" "v" "\v" "b" "\b"
"n" "\n" "f" "\f" "r" "\r"
"t" "\t"} $ $))
:main (+ (some (+ :unicode-esc :escape (<- 1))) -1)}))
(defn decode
``
Returns a janet object after parsing JSON. If `keywords` is truthy,
string keys will be converted to keywords. If `nils` is truthy, `null`
will become `nil` instead of the keyword `:json/null`.
``
[json-source &opt keywords nils]
(def json-parser
{:null (if nils
~(/ (<- (+ "null" "Null")) nil)
~(/ (<- (+ "null" "Null")) :json/null))
:bool-t ~(/ (<- (+ "true")) true)
:bool-f ~(/ (<- (+ "false")) false)
:number ~(/ (<- (* (? "-") :d+ (? (* "." :d+)))) ,|(scan-number $))
:string ~(/ (* "\"" (<- (to (* (> -1 (not "\\")) "\"")))
(* (> -1 (not "\\")) "\""))
,|(string/join (peg/match utf-8->bytes $)))
:array ~(/ (* "[" :s* (? (* :value (any (* :s* "," :value)))) "]") ,|(array ;$&))
:key-value (if keywords
~(* :s* (/ :string ,|(keyword $)) :s* ":" :value)
~(* :s* :string :s* ":" :value))
:object ~(/ (* "{" :s* (? (* :key-value (any (* :s* "," :key-value)))) "}")
,|(from-pairs (partition 2 $&)))
:value ~(* :s* (+ :null :bool-t :bool-f :number :string :array :object) :s*)
:unmatched ~(/ (<- (to (+ :value -1))) ,|[:unmatched $])
:main ~(some (+ :value "\n" :unmatched))})
(first (peg/match (peg/compile json-parser) json-source)))
(def- bytes->utf-8
(peg/compile
~{:four-byte (/ (* (<- (range "\xf0\xff")) (<- 1) (<- 1) (<- 1))
,|(bor (blshift (band (first $0) 0x07) 18)
(blshift (band (first $1) 0x3F) 12)
(blshift (band (first $2) 0x3F) 6)
(blshift (band (first $3) 0x3F) 0)))
:three-byte (/ (* (<- (range "\xe0\xef")) (<- 1) (<- 1))
,|(bor (blshift (band (first $0) 0x0F) 12)
(blshift (band (first $1) 0x3F) 6)
(blshift (band (first $2) 0x3F) 0)))
:two-byte (/ (* (<- (range "\x80\xdf")) (<- 1))
,|(bor (blshift (band (first $0) 0x1F) 6)
(blshift (band (first $1) 0x3F) 0)))
:multi-byte (/ (+ :two-byte :three-byte :four-byte)
,|(if (< $ 0x10000)
(string/format "\\u%04X" $)
(string/format "\\u%04X\\u%04X"
(+ (brshift (- $ 0x10000) 10) 0xD800)
(+ (band (- $ 0x10000) 0x3FF) 0xDC00))))
:one-byte (<- (range "\x20\x7f"))
:0to31 (/ (<- (range "\0\x1F"))
,|(or ({"\a" "\\u0007" "\b" "\\u0008"
"\t" "\\u0009" "\n" "\\u000A"
"\v" "\\u000B" "\f" "\\u000C"
"\r" "\\u000D"} $)
(string/format "\\u%04X" (first $))))
:backslash (/ (<- "\\") "\\\\")
:quote (/ (<- "\"") "\\\"")
:main (+ (some (+ :0to31 :backslash :quote :one-byte :multi-byte)) -1)}))
(defn- encodeone [x depth]
(if (> depth 1024) (error "recurred too deeply"))
(cond
(= x :json/null) "null"
(= x nil) "null"
(bytes? x) (string "\"" (string/join (peg/match bytes->utf-8 x)) "\"")
(indexed? x) (string "[" (string/join (map |(encodeone $ (inc depth)) x) ",") "]")
(dictionary? x) (string "{" (string/join
(seq [[k v] :in (pairs x)]
(string "\"" (string/join (peg/match bytes->utf-8 k)) "\"" ":" (encodeone v (inc depth)))) ",") "}")
(case (type x)
:nil "null"
:boolean (string x)
:number (string x)
(error "type not supported"))))
(defn encode
``
Encodes a janet value in JSON (utf-8). If `buf` is provided, the formated
JSON is append to `buf` instead of a new buffer. Returns the modifed buffer.
``
[x &opt buf]
(letv [ret (encodeone x 0)]
(if (and buf (buffer? buf))
(buffer/push ret)
(thaw ret))))

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# an integrated Ludus interpreter
# devised in order to run under wasm
# takes a string, returns a string with a json object
# (try (os/cd "janet") ([_] nil)) # for REPL
(import /src/scanner :as s)
(import /src/parser :as p)
(import /src/validate :as v)
(import /src/interpreter :as i)
(import /src/errors :as e)
(import /src/base :as b)
(import /src/prelude :as prelude)
(import /src/json :as j)
(defn ludus [source]
(when (= :error prelude/pkg) (error "could not load prelude"))
(def ctx @{:^parent prelude/ctx})
(def errors @[])
(def draw @[])
(var result @"")
(def console @"")
(setdyn :out console)
(def out @{:errors errors :draw draw :result result :console console})
(def scanned (s/scan source))
(when (any? (scanned :errors))
(each err (scanned :errors)
(e/scan-error err))
(break (-> out j/encode string)))
(def parsed (p/parse scanned))
(when (any? (parsed :errors))
(each err (parsed :errors)
(e/parse-error err))
(break (-> out j/encode string)))
(def validated (v/valid parsed ctx))
(when (any? (validated :errors))
(each err (validated :errors)
(e/validation-error err))
(break (-> out j/encode string)))
(try
(set result (i/interpret (parsed :ast) ctx))
([err]
(e/runtime-error err)
(break (-> out j/encode string))))
(setdyn :out stdout)
(set (out :result) (b/show result))
(var post @{})
(try
(set post (i/interpret prelude/post/ast ctx))
([err] (e/runtime-error err)))
(set (out :draw) (post :draw))
# out
(-> out j/encode string)
)
(comment
# (do
# (def start (os/clock))
(def source `
box foo = :bar
store! (foo, :baz)
unbox (foo)
`)
(def out (-> source
ludus
j/decode
))
# (def end (os/clock))
(setdyn :out stdout)
(pp out)
(def console (out "console"))
(print console)
(def result (out "result"))
(print result)
# (print (- end start))
)

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(ns ludus.analyzer
(:require
[ludus.ast :as ast]
[ludus.token :as token]))
(defn analyze [ast] ast)
(comment "
Here's where we do a bunch of static analysis.
Some things we might wish for:
* No unused bindings
* No unbound names
* Compound `loop` and `gen` forms must have LHS's (tuple patterns) of the same length
* Recur must be in tail position in `loop`s
* Tail call optimization for simple recursion (rewrite it as a loop?)
* Check arities for statically known functions
* Enforce single-member tuple after called keywords
* Placeholders may only appear in tuples in synthetic expressions
* Each of these may have zero or one placeholders
* Arity of called keywords must be 1
")

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(ns ludus.ast)

1
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(ns ludus.collections)

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(ns ludus.core
"A tree-walk interpreter for the Ludus language."
(:require
[ludus.scanner :as scanner]))
(defn- report [line, where, message]
(println (str "[line " line "] Error" where ": " message)))
(defn- error [line, message]
(report line "" message))
(defn- run [source]
(let [tokens (scanner/scan source)]
(run! println tokens)))
(defn- run-file [path]
(let [source (slurp path)]
(run source)))
(defn- run-prompt []
(loop [_ ""]
(print "Ludus >> ")
(flush)
(when-let [line (read-line)]
(recur (run line)))))
(defn -main [& args]
(cond
(> (count args) 1) (do
(println "Usage: ludus [script]")
(System/exit 64))
(= (count args) 1) (run-file (first args))
:else (run-prompt)))

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(ns ludus.interpreter
(:require
[ludus.parser :as parser]
[ludus.scanner :as scanner]
[ludus.ast :as ast]
[ludus.collections :as colls]
[ludus.prelude :as prelude]
[clojure.pprint :as pp]))
;; right now this is not very efficient:
;; it's got runtime checking
;; we should be able to do these checks statically
;; that's for later, tho
(defn- resolve [word ctx-atom]
(let [ctx @ctx-atom]
(if (contains? ctx word)
(get ctx word)
(if (contains? ctx ::parent)
(recur word (::parent ctx))
(throw (new Exception (str "Unbound name: " word)))))))
(declare interpret match)
(defn- match-tuple [pattern value ctx-atom]
(cond
(not (vector? value)) {:success false :reason "Could not match non-tuple value to tuple"}
(not (= ::colls/tuple (first value))) {:success false :reason "Could not match list to tuple"}
(not (= (:length pattern) (dec (count value))))
{:success false :reason "Cannot match tuples of different lengths"}
(= 0 (:length pattern) (dec (count value))) {:success true :ctx {}}
:else (let [members (:members pattern)]
(loop [i (:length pattern)
ctx {}]
(if (= 0 i)
{:success true :ctx ctx}
(let [match? (match (nth members (dec i)) (nth value i) ctx-atom)]
(if (:success match?)
(recur (dec i) (merge ctx (:ctx match?)))
{:success false :reason (str "Could not match " pattern " with " value)})))))))
(defn- match [pattern value ctx-atom]
(let [ctx @ctx-atom]
(case (::ast/type pattern)
::ast/placeholder {:success true :ctx {}}
::ast/atom
(let [match-value (:value pattern)]
(if (= match-value value)
{:success true :ctx {}}
{:success false
:reason (str "No match: Could not match " match-value " with " value)}))
::ast/word
(let [word (:word pattern)]
(if (contains? ctx word)
{:success false :reason (str "Name " word " is already bound")}
{:success true :ctx {word value}}))
::ast/tuple (match-tuple pattern value ctx-atom)
(do
(println "ERROR! Unexpected pattern:")
(pp/pprint pattern)))))
(defn- update-ctx [ctx new-ctx]
(println "Adding to context:")
(pp/pprint new-ctx)
(merge ctx new-ctx))
;; TODO: get "if let" pattern working
;; TODO: get typed exceptions to distinguish panics
(defn- interpret-let [ast ctx]
(let [pattern (:pattern ast)
expr (:expr ast)
value (interpret expr ctx)
match (match pattern value ctx)
success (:success match)]
(if success
(swap! ctx update-ctx (:ctx match))
(throw (ex-info (:reason match) {})))
value))
(defn- interpret-if [ast ctx]
(let [if-expr (:if ast)
then-expr (:then ast)
else-expr (:else ast)
if-value (interpret if-expr ast)]
(if if-value
(interpret then-expr ctx)
(interpret else-expr ctx))))
(defn- interpret-match [ast ctx]
(let [match-expr (:expr ast)
expr (interpret match-expr ctx)
clauses (:clauses ast)]
(loop [clause (first clauses)
clauses (rest clauses)]
(if clause
(let [pattern (:pattern clause)
body (:body clause)
new-ctx (atom {::parent ctx})
match? (match pattern expr new-ctx)
success (:success match?)
clause-ctx (:ctx match?)]
(if success
(do
(swap! new-ctx #(merge % clause-ctx))
(interpret body new-ctx))
(recur (first clauses) (rest clauses))))
(throw (ex-info "Match Error: No match found" {}))))))
(defn- interpret-called-kw [kw tuple ctx]
(if (not (= 1 (:length tuple)))
;; TODO: check this statically
(throw (ex-info "Called keywords must be unary" {}))
(let [kw (interpret kw ctx)
map (second (interpret tuple ctx))]
(get map kw))))
(defn- call-fn [fn tuple ctx]
(let [passed (interpret tuple ctx)]
(case (::ast/type fn)
::ast/clj (apply (:body fn) (next passed))
(throw (ex-info "I don't know how to call that" {:fn fn})))))
;; TODO: add placeholder partial application
(defn- interpret-synthetic-term [prev-value curr ctx]
(let [type (::ast/type curr)]
(if (= type ::ast/atom)
(get prev-value (:value curr))
(call-fn prev-value curr ctx))))
(defn- interpret-synthetic [ast ctx]
(let [terms (:terms ast)
first (first terms)
second (second terms)
rest (rest (rest terms))
first-term-type (::ast/type first)
first-val (if (= first-term-type ::ast/atom)
(interpret-called-kw first second ctx)
(interpret-synthetic-term (interpret first ctx) second ctx))]
(reduce #(interpret-synthetic-term %1 %2 ctx) first-val rest)))
(defn- map-values [f]
(map (fn [kv]
(let [[k v] kv]
[k (f v)]))))
(defn interpret [ast ctx]
(case (::ast/type ast)
::ast/atom (:value ast)
::ast/word (resolve (:word ast) ctx)
::ast/let (interpret-let ast ctx)
::ast/if (interpret-if ast ctx)
::ast/match (interpret-match ast ctx)
::ast/synthetic (interpret-synthetic ast ctx)
::ast/block
(let [exprs (:exprs ast)
inner (pop exprs)
last (peek exprs)
ctx (atom {::parent ctx})]
(run! #(interpret % ctx) inner)
(interpret last ctx))
::ast/script
(let [exprs (:exprs ast)
inner (pop exprs)
last (peek exprs)
ctx (atom prelude/prelude)]
(run! #(interpret % ctx) inner)
(interpret last ctx))
;; note that the runtime representations of collections is
;; unboxed in the tree-walk interpreter
;; tuples & lists are both vectors, the first element
;; distinguishes them
::ast/tuple
(let [members (:members ast)]
(into [::colls/tuple] (map #(interpret % ctx)) members))
::ast/list
(let [members (:members ast)]
(into [::colls/list] (map #(interpret % ctx)) members))
::ast/set
(let [members (:members ast)]
(into #{} (map #(interpret % ctx)) members))
::ast/hash
(let [members (:members ast)]
(into {} (map-values #(interpret % ctx)) members))
(do
(println "ERROR! Unexpected AST node:")
(pp/pprint ast))))
(do
(def source "
if false then :yay else print(:foo)
")
(println "")
(println "****************************************")
(println "*** *** NEW INTERPRETATION *** ***")
(println "")
(-> source
(scanner/scan)
(parser/parse)
(::parser/ast)
(interpret {})
(pp/pprint)))
(comment "
Left to do:
* if-let pattern
* improve panics
* add location info for panics
")

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(ns ludus.parser
(:require
[ludus.token :as token]
[ludus.scanner :as scanner]
[ludus.ast :as ast]
[clojure.pprint :as pp]
[clojure.set :as s]))
;; a parser map and some functions to work with them
(defn- parser [tokens]
{::tokens tokens ::token 0 ::ast {} ::errors []})
(defn- current [parser]
(nth (::tokens parser) (::token parser) nil))
(defn- peek [parser]
(nth (::tokens parser) (inc (::token parser)) nil))
(defn- at-end? [parser]
(let [curr (current parser)]
(or (nil? curr) (= ::token/eof (::token/type curr)))))
(defn- advance [parser]
(update parser ::token inc))
(defn- token-type [parser]
(::token/type (current parser)))
(defn- node-type [parser]
(get-in parser [::ast ::ast/type]))
;; some forward declarations
(declare parse-expr parse-word parse-pattern)
;; handle some errors
(def sync-on #{::token/newline
::token/semicolon
::token/comma
::token/rparen
::token/rbracket
::token/rbrace
::token/eof})
(defn- sync [parser message origin end]
(let [poison {::ast/type ::ast/poison
:message message
:origin origin
:end end}]
(-> parser
(assoc ::ast poison)
(update ::errors conj poison))))
(defn- poisoned? [parser]
(= ::ast/poison (get-in parser [::ast ::ast/type])))
(defn- panic
([parser message] (panic parser message sync-on))
([parser message sync-on]
(println (str "PANIC!!! in the parser: " message))
(let [sync-on (conj (if (set? sync-on) sync-on #{sync-on}) ::token/eof)
origin (current parser)]
(loop [parser parser]
(let [curr (current parser)
type (::token/type curr)]
(if (or (at-end? parser) (contains? sync-on type))
(sync parser message origin curr)
(recur (advance parser))))))))
;; some helper functions
(defn- expect [tokens message parser]
(let [curr (current parser)
tokens (if (set? tokens) tokens #{tokens})
type (::token/type curr)]
(if (contains? tokens type)
(advance parser)
(-> parser
(advance)
(panic message tokens)))))
(defn- expect* [tokens message parser]
(let [curr (current parser)
tokens (if (set? tokens) tokens #{tokens})
type (::token/type curr)]
(if (contains? tokens type)
{:success true :parser (advance parser)}
{:success false :parser (panic (advance parser) message)})))
(defn- accept [tokens parser]
(let [curr (current parser)
tokens (if (set? tokens) tokens #{tokens})
type (::token/type curr)]
(if (contains? tokens type)
(advance parser)
parser)))
(defn- accept-many [tokens parser]
(let [tokens (if (set? tokens) tokens #{tokens})]
(loop [parser parser]
(let [curr (current parser)
type (::token/type curr)]
(if (contains? tokens type)
(recur (advance parser))
parser)))))
;; various parsing functions
(defn- parse-atom [parser]
(let [token (current parser)]
(-> parser
(advance)
(assoc ::ast {::ast/type ::ast/atom
:token token
:value (::token/literal token)}))))
;; just a quick and dirty map to associate atomic words with values
(def atomic-words {::token/nil nil
::token/true true
::token/false false})
(defn parse-atomic-word [parser]
(let [token (current parser)]
(-> parser
(advance)
(assoc ::ast {::ast/type ::ast/atom
:token token
:value (get atomic-words (::token/type token))}))))
(defn- add-member [members member]
(if (nil? member)
members
(conj members member)))
(defn- parse-tuple [origin]
(loop [parser (accept-many #{::token/newline ::token/comma} (advance origin))
members []
current_member nil]
(let [curr (current parser)]
(case (token-type parser)
::token/rparen (let [ms (add-member members current_member)]
(assoc (advance parser) ::ast
{::ast/type ::ast/tuple
:length (count ms)
:members ms}))
(::token/comma ::token/newline)
(recur
(accept-many #{::token/comma ::token/newline} parser)
(add-member members current_member) nil)
(::token/rbrace ::token/rbracket)
(panic parser (str "Mismatched enclosure in tuple: " (::token/lexeme curr)))
::token/eof
(panic (assoc origin ::errors (::errors parser)) "Unterminated tuple" ::token/eof)
(let [parsed (parse-expr parser #{::token/comma ::token/newline ::token/rparen})]
(recur parsed members (::ast parsed)))))))
(defn- parse-list [origin]
(loop [parser (accept-many #{::token/newline ::token/comma} (advance origin))
members []
current_member nil]
(let [curr (current parser)]
(case (token-type parser)
::token/rbracket (let [ms (add-member members current_member)]
(assoc (advance parser) ::ast
{::ast/type ::ast/list
:members ms}))
(::token/comma ::token/newline)
(recur
(accept-many #{::token/comma ::token/newline} parser)
(add-member members current_member) nil)
(::token/rbrace ::token/rparen)
(panic parser (str "Mismatched enclosure in list: " (::token/lexeme curr)))
::token/eof
(panic (assoc origin ::errors (::errors parser)) "Unterminated list" ::token/eof)
(let [parsed (parse-expr parser #{::token/comma ::token/newline ::token/rbracket})]
(recur parsed members (::ast parsed)))))))
(defn- parse-set [origin]
(loop [parser (accept-many #{::token/newline ::token/comma} (advance origin))
members []
current_member nil]
(let [curr (current parser)]
(case (token-type parser)
::token/rbrace (let [ms (add-member members current_member)]
(assoc (advance parser) ::ast
{::ast/type ::ast/set
:members ms}))
(::token/comma ::token/newline)
(recur
(accept-many #{::token/comma ::token/newline} parser)
(add-member members current_member) nil)
(::token/rbracket ::token/rparen)
(panic parser (str "Mismatched enclosure in set: " (::token/lexeme curr)))
::token/eof
(panic (assoc origin ::errors (::errors parser)) "Unterminated set" ::token/eof)
(let [parsed (parse-expr parser #{::token/comma ::token/newline ::token/rbrace})]
(recur parsed members (::ast parsed)))))))
(defn- parse-hash [origin]
(loop [parser (accept-many #{::token/newline ::token/comma} (advance origin))
members {}
current_member nil]
(let [curr (current parser)]
(case (token-type parser)
::token/rbrace (let [ms (add-member members current_member)]
(assoc (advance parser) ::ast
{::ast/type ::ast/hash
:members ms}))
(::token/comma ::token/newline)
(recur
(accept-many #{::token/comma ::token/newline} parser)
(add-member members current_member) nil)
(::token/rbracket ::token/rparen)
(panic parser (str "Mismatched enclosure in set: " (::token/lexeme curr)))
::token/eof
(panic (assoc origin ::errors (::errors parser)) "Unterminated set" ::token/eof)
::token/word
(if (not current_member) (let [parsed (parse-word parser) word (get-in parsed [::ast :word])]
(recur parsed members {(keyword word) (::ast parsed)}))
(panic parser "Hashmap entries must be single words or keyword+expression pairs." #{::token/rbrace}))
::token/keyword
(if (not current_member) (let [kw (parse-atom parser) expr (parse-expr kw #{::token/comma ::token/newline ::token/rbrace})]
(println "found keyword/expr pair:" (:value kw))
(pp/pprint (::ast expr))
(recur expr members {(:value (::ast kw)) (::ast expr)}))
(panic parser "Hashmap entries must be single words or keyword+expression pairs." #{::token/rbrace}))
(panic parser "Hashmap entries must be single words or keyword+expression pairs" #{::token/rbrace})))))
(defn- parse-block [origin]
(loop [parser (accept-many #{::token/newline ::token/semicolon} (advance origin))
exprs []
current_expr nil]
(let [curr (current parser)]
(case (token-type parser)
::token/rbrace
(let [es (add-member exprs current_expr)]
(if (empty? es)
(advance (panic parser "Blocks must have at least one expression"))
(assoc (advance parser) ::ast {::ast/type ::ast/block
:exprs es})))
(::token/semicolon ::token/newline)
(recur
(accept-many #{::token/newline ::token/semicolon} parser)
(add-member exprs current_expr) nil)
(::token/rbracket ::token/rparen)
(panic parser (str "Mismatched enclosure in block: " (::token/lexeme curr)))
::token/eof
(panic (assoc origin ::errors (::errors parser)) "Unterminated block" ::token/eof)
(let [parsed
(if current_expr
(panic parser "Expected end of expression" #{::token/semicolon ::token/newline})
(parse-expr parser))]
(recur parsed exprs (::ast parsed)))))))
(defn parse-script [parser]
(loop [parser (accept-many #{::token/newline ::token/semicolon} parser)
exprs []
current_expr nil]
(case (token-type parser)
::token/eof
(let [es (add-member exprs current_expr)]
(if (empty? es)
(panic parser "Scripts must have at least one expression")
(assoc parser ::ast {::ast/type ::ast/script :exprs es})))
(::token/semicolon ::token/newline)
(recur
(accept-many #{::token/semicolon ::token/newline} parser)
(add-member exprs current_expr)
nil)
(let [parsed
(if current_expr
(panic parser "Expected end of expression" #{::token/semicolon ::token/newline})
(parse-expr parser))]
(recur parsed exprs (::ast parsed))))))
(defn- parse-synthetic [parser]
(loop [parser parser
terms []]
(let [curr (current parser)
type (::token/type curr)]
(case type
::token/keyword
(recur (advance parser) (conj terms (::ast (parse-atom parser))))
::token/word
(recur (advance parser) (conj terms (::ast (parse-word parser))))
::token/lparen
(let [parsed (parse-tuple parser)]
(recur parsed (conj terms (::ast parsed))))
(assoc parser ::ast {::ast/type ::ast/synthetic :terms terms})))))
(defn- parse-word [parser]
(let [curr (current parser)]
(-> parser
(advance)
(assoc ::ast {::ast/type ::ast/word :word (::token/lexeme curr)}))))
(def sync-pattern (s/union sync-on #{::token/equals ::token/rarrow}))
(defn- parse-tuple-pattern [origin]
(loop [parser (accept-many #{::token/newline ::token/comma} (advance origin))
members []
current_member nil]
(let [curr (current parser)]
(case (token-type parser)
::token/rparen (let [ms (add-member members current_member)]
(assoc (advance parser) ::ast
{::ast/type ::ast/tuple
:length (count ms)
:members ms}))
(::token/comma ::token/newline)
(recur
(accept-many #{::token/comma ::token/newline} parser)
(add-member members current_member) nil)
(::token/rbrace ::token/rbracket)
(panic parser (str "Mismatched enclosure in tuple: " (::token/lexeme curr)))
::token/eof
(panic (assoc origin ::errors (::errors parser)) "Unterminated tuple" ::token/eof)
(let [parsed (parse-pattern parser)]
(recur parsed members (::ast parsed)))))))
(defn- parse-pattern [parser]
(let [curr (current parser)
type (::token/type curr)]
(case type
::token/placeholder (-> parser
(advance)
(assoc ::ast {::ast/type ::ast/placeholder}))
::token/word (parse-word parser)
(::token/number ::token/string ::token/keyword) (parse-atom parser)
::token/lparen (parse-tuple-pattern parser)
::token/error
(panic parser (:message (current parser)) sync-pattern)
(panic parser "Expected pattern" sync-pattern))))
(defn- parse-let-expr [parser pattern]
(let [expr (parse-expr parser)]
(assoc expr ::ast {::ast/type ::ast/let
:pattern (::ast pattern) :expr (::ast expr)})))
(defn- parse-assignment [parser]
(let [assignment (expect* ::token/equals "Expected assignment" parser)
success (:success assignment)]
(if success
(parse-let-expr (:parser assignment) parser)
(panic parser "Expected assignment"))))
(defn- parse-let [parser]
(let [pattern (parse-pattern (advance parser))]
(parse-assignment pattern)))
(defn- parse-else [parser]
(let [ast (::ast parser)
else-kw (expect* ::token/else "Expected else clause after then" parser)
success (:success else-kw)
else-kw-parser (:parser else-kw)]
(if success
(let [expr (parse-expr else-kw-parser)
else-expr (::ast expr)]
(assoc expr ::ast (assoc ast :else else-expr)))
else-kw-parser)))
(defn- parse-then [parser]
(let [ast (::ast parser)
then-kw (expect* ::token/then "Expected then clause after if" parser)
success (:success then-kw)
then-kw-parser (:parser then-kw)]
(if success
(let [expr (parse-expr then-kw-parser (conj sync-on ::token/else))
then-expr (::ast expr)]
(parse-else (accept ::token/newline (assoc expr ::ast (assoc ast :then then-expr)))))
then-kw-parser)))
(defn- parse-if [parser]
(let [if-expr (parse-expr (advance parser) #{::token/newline ::token/then})
ast (assoc if-expr ::ast {::ast/type ::ast/if :if (::ast if-expr)})]
(parse-then (accept ::token/newline ast))))
(defn- parse-match-clause [parser]
(let [pattern (parse-pattern parser)
rarrow (expect* #{::token/rarrow} "Expected arrow after pattern" pattern)]
(if (:success rarrow)
(let [body (parse-expr (:parser rarrow))]
(assoc body ::ast {::ast/type ::ast/clause
:pattern (::ast pattern) :body (::ast body)}))
(panic pattern "Expected -> in match clause. Clauses must be in the form pattern -> expression" #{::token/newline ::token/rbrace}))))
(defn- parse-match-clauses [parser]
(loop [parser (accept-many #{::token/newline} (advance parser))
clauses []]
(let [curr (current parser)]
(case (::token/type curr)
::token/rbrace
(assoc (advance parser) ::ast {::ast/type ::ast/clauses :clauses clauses})
::token/newline
(recur (accept-many #{::token/newline} parser) clauses)
(let [clause (parse-match-clause parser)]
(recur (accept-many #{::token/newline} clause) (conj clauses (::ast clause))))))))
(defn- parse-match [parser]
(let [match-expr (parse-expr (advance parser) #{::token/with})
match-header (expect* #{::token/with} "Expected with" match-expr)]
(if (:success match-header)
(let [clauses (:parser match-header)]
(if (= (token-type clauses) ::token/lbrace)
;; match expression with one or many clauses in braces
(let [clauses (parse-match-clauses clauses)]
(assoc clauses ::ast {::ast/type ::ast/match
:expr (::ast match-expr)
:clauses (get-in clauses [::ast :clauses])}))
;; match expression with single match clause
(let [clause (parse-match-clause clauses)]
(assoc clause ::ast {::ast/type ::ast/match
:expr (::ast match-expr)
:clauses [(::ast clause)]}))))
(panic parser "Expected with after match expression"))))
(defn- parse-fn-clause [parser]
(if (not (= ::token/lparen (token-type parser)))
(panic parser "Function clauses must begin with tuple patterns")
(let [pattern (parse-tuple-pattern parser)
arrow (expect* #{::token/rarrow} "Expected arrow" pattern)
body (parse-expr (:parser arrow))]
(if (:success arrow)
(assoc body ::ast {::ast/type ::ast/clause
:pattern (::ast pattern) :body (::ast body)})
(panic pattern "Expected -> in function clause. Clauses must be in the form of (pattern) -> expression")))))
(defn- parse-fn-clauses [parser]
(loop [parser (accept-many #{::token/newline} (advance parser))
clauses []]
(let [curr (current parser)]
(case (::token/type curr)
::token/rbrace
(assoc (advance parser) ::ast {::ast/type ::ast/clauses :clauses clauses})
::token/newline
(recur (accept-many #{::token/newline} parser) clauses)
(let [clause (parse-fn-clause parser)]
(recur (accept-many #{::token/newline} clause) (conj clauses (::ast clause))))))))
(defn- parse-named-fn [parser]
(let [name (parse-word parser)]
(case (token-type name)
::token/lparen
(let [clause (parse-fn-clause name)]
(assoc clause ::ast {::ast/type ::ast/fn
:name (get-in name [::ast :word])
:clauses [(::ast clause)]}))
::token/lbrace
(let [clauses (parse-fn-clauses name)]
(assoc clauses ::ast {::ast/type ::ast/match
:name (get-in name [::ast :word])
:clauses (get-in clauses [::ast :clauses])}))
(panic name "Expected one or more function clauses"))))
(defn- parse-fn [parser]
(let [first (advance parser)]
(case (::token/type (current first))
::token/lparen
(let [clause (parse-fn-clause first)]
(assoc clause ::ast {::ast/type ::ast/fn
:name "anonymous"
:clauses [(::ast clause)]}))
::token/word (parse-named-fn first)
(panic parser "Expected name or clause after fn"))))
(defn- parse-expr
([parser] (parse-expr parser sync-on))
([parser sync-on]
(let [token (current parser)]
(case (::token/type token)
(::token/number ::token/string)
(parse-atom parser)
::token/keyword
(let [next (peek parser)
type (::token/type next)]
(if (= type ::token/lparen)
(parse-synthetic parser)
(parse-atom parser)))
::token/word
(let [next (peek parser)
type (::token/type next)]
(case type
(::token/lparen ::token/keyword) (parse-synthetic parser)
(parse-word parser)))
(::token/nil ::token/true ::token/false)
(parse-atomic-word parser)
::token/lparen (parse-tuple parser)
::token/lbracket (parse-list parser)
::token/startset (parse-set parser)
::token/starthash (parse-hash parser)
::token/lbrace (parse-block parser)
::token/let (parse-let parser)
::token/if (parse-if parser)
::token/match (parse-match parser)
::token/fn (parse-fn parser)
;; TODO: improve handling of comments?
;; Scanner now just skips comments
;; ::token/comment (advance parser)
::token/error (panic parser (:message token) sync-on)
(::token/rparen ::token/rbrace ::token/rbracket)
(panic parser (str "Unbalanced enclosure: " (::token/lexeme token)))
(::token/semicolon ::token/comma)
(panic parser (str "Unexpected delimiter: " (::token/lexeme token)))
(panic parser "Expected expression" sync-on)))))
(defn parse [lexed]
(-> lexed
(:tokens)
(parser)
(parse-script)))
(do
(def pp pp/pprint)
(def source "fn foo {
(foo, bar, baz) -> {:foo}
}
")
(def lexed (scanner/scan source))
(def tokens (:tokens lexed))
(def p (parser tokens))
(println "")
(println "")
(println "******************************************************")
(println "")
(println "*** *** NEW PARSE *** ***")
(-> p
(parse-fn)
(::ast)
(pp)))
(comment "
Further thoughts/still to do:
* Functions
* anonymous, simple
* named, simple
* anonymous, complex?
* named, complex
* with docstrings?
* Cond expressions
* Loops
* Structs
* Namespaces
* Types (:|)
* Modules
* Add `as` clauses to patterns
* Add `when` clauses to patterns
* var/mut
* ref/swap
* Splats in lists, hashmaps, sets
* AST nodes should include tokens/locations
- at current, only atoms do this
* Improve error handling in hashmap parsing
* Consider error handling in match expressions
* Add treatment of ignored variables
* Placeholders
* How much in parser, how much in analysis?
Some architectural changes:
* UGH, this code is just kind of a mess and hard to reason about
* Especially sequential forms
* Parsers are hard
* One idea:
* Refactor everything so that it returns a success or failure
* Because this is all stateless, in sequential forms, you can just do all the things
* This lets you do one let (with everything building up) and then a cond with bespoke errors/panics
* This also still lets you encapsulate parsererrors with poisoned nodes
")

26
src/ludus/prelude.clj Normal file
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@ -0,0 +1,26 @@
(ns ludus.prelude
(:require
[ludus.ast :as ast]))
(def eq {:name "eq"
::ast/type ::ast/clj
:body =})
(def add {:name "add"
::ast/type ::ast/clj
:body +})
(def panic {:name "panic"
::ast/type ::ast/clj
:body (fn [& args] (throw (ex-info "Ludus panicked!" {:args args})))})
(def print {:name "print"
::ast/type ::ast/clj
:body (fn [& args]
(println (str args))
:ok)})
(def prelude {"eq" eq
"add" add
"panic" panic
"print" print})

314
src/ludus/scanner.clj Normal file
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(ns ludus.scanner
(:require
[ludus.token :as token]
[clojure.pprint :as pp]
[clojure.edn :as edn]
[clojure.string :as s]))
(def reserved-words
"List of Ludus reserved words."
;; see ludus-spec repo for more info
{"as" ::token/as
"cond" ::token/cond
"do" ::token/do
"else" ::token/else
"false" ::token/false
"fn" ::token/fn
"if" ::token/if
"import" ::token/import
"let" ::token/let
"match" ::token/match
"mut" ::token/mut
"nil" ::token/nil
"panic!" ::token/panic
"then" ::token/then
"true" ::token/true
"var" ::token/var
"with" ::token/with
;; below here, probable
"defer" ::token/defer
"gen" ::token/gen
"loop" ::token/loop
"ns" ::token/ns
"recur" ::token/recur
"repeat" ::token/repeat
"test" ::token/test
"wait" ::token/wait
"yield" ::token/yield
;; below here, possible
"when" ::token/when})
(defn- new-scanner
"Creates a new scanner."
[source]
{::source source
::length (count source)
::errors []
::start 0
::current 0
::line 1
::tokens []})
(defn- at-end?
"Tests if a scanner is at end of input."
[scanner]
(>= (::current scanner) (::length scanner)))
(defn- current-char
"Gets the current character of the scanner."
[scanner]
(nth (::source scanner) (::current scanner) nil))
(defn- advance
"Advances the scanner by a single character."
[scanner]
(update scanner ::current inc))
(defn- next-char
"Gets the next character from the scanner."
[scanner]
(current-char (advance scanner)))
(defn- current-lexeme
[scanner]
(subs (::source scanner) (::start scanner) (::current scanner)))
(defn- char-in-range? [start end char]
(and char
(>= (int char) (int start))
(<= (int char) (int end))))
(defn- digit? [c]
(char-in-range? \0 \9 c))
(defn- nonzero-digit? [c]
(char-in-range? \1 \9 c))
;; for now, use very basic ASCII charset in words
;; TODO: research the implications of using the whole
;; (defn- alpha? [c] (boolean (re-find #"\p{L}" (str c))))
(defn- alpha? [c]
(or (char-in-range? \a \z c) (char-in-range? \A \Z c)))
;; legal characters in words
(def word-chars #{\_ \? \! \* \/})
(defn- word-char? [c]
(or (alpha? c) (digit? c) (contains? word-chars c)))
(defn- whitespace? [c]
(or (= c \space) (= c \tab)))
(def terminators #{\: \; \newline \{ \} \( \) \[ \] \$ \# \- \< \& \, \| nil \\})
(defn- terminates? [c]
(or (whitespace? c) (contains? terminators c)))
(defn- add-token
([scanner token-type]
(add-token scanner token-type nil))
([scanner token-type literal]
(update scanner ::tokens conj
(token/token
token-type
(current-lexeme scanner)
literal
(::line scanner)
(::start scanner)))))
;; TODO: errors should also be in the vector of tokens
;; The goal is to be able to be able to hand this to an LSP?
;; Do we need a different structure
(defn- add-error [scanner msg]
(let [token (token/token
::token/error
(current-lexeme scanner)
nil
(::line scanner)
(::start scanner))
err-token (assoc token :message msg)]
(-> scanner
(update ::errors conj err-token)
(update ::tokens conj err-token))))
(defn- add-keyword
[scanner]
(loop [scanner scanner
key ""]
(let [char (current-char scanner)]
(cond
(terminates? char) (add-token scanner ::token/keyword (keyword key))
(word-char? char) (recur (advance scanner) (str key char))
:else (add-error scanner (str "Unexpected " char "after keyword :" key))))))
;; TODO: improve number parsing?
;; Currently this uses Clojure's number formatting rules (since we use the EDN reader)
;; These rules are here: https://cljs.github.io/api/syntax/number
(defn- add-number [char scanner]
(loop [scanner scanner
num (str char)
float? false]
(let [curr (current-char scanner)]
(cond
(= curr \_) (recur (advance scanner) num float?) ;; consume underscores unharmed
(= curr \.) (if float?
(add-error scanner (str "Unexpected second decimal point after " num "."))
(recur (advance scanner) (str num curr) true))
(terminates? curr) (add-token scanner ::token/number (edn/read-string num))
(digit? curr) (recur (advance scanner) (str num curr) float?)
:else (add-error scanner (str "Unexpected " curr " after number " num "."))))))
;; TODO: add string interpolation
;; This still has to be devised
(defn- add-string
[scanner]
(loop [scanner scanner
string ""]
(let [char (current-char scanner)]
(case char
\newline (add-error scanner "Unterminated string.")
\" (add-token (advance scanner) ::token/string string)
\\ (let [next (next-char scanner)
scanner (if (= next \newline)
(update scanner ::line inc)
scanner)]
(recur (advance (advance scanner)) (str string next)))
(if (at-end? scanner)
(add-error scanner "Unterminated string.")
(recur (advance scanner) (str string char)))))))
(defn- add-word
[char scanner]
(loop [scanner scanner
word (str char)]
(let [curr (current-char scanner)]
(cond
(terminates? curr) (add-token scanner (get reserved-words word ::token/word))
(word-char? curr) (recur (advance scanner) (str word curr))
:else (add-error scanner (str "Unexpected " curr " after word " word "."))))))
(defn- add-ignored
[scanner]
(loop [scanner scanner
ignored "_"]
(let [char (current-char scanner)]
(cond
(terminates? char) (add-token scanner ::token/ignored)
(word-char? char) (recur (advance scanner) (str ignored char))
:else (add-error scanner (str "Unexpected " char " after word " ignored "."))))))
(defn- add-comment [char scanner]
(loop [scanner scanner
comm (str char)]
(let [char (current-char scanner)]
(if (= \newline char)
(update scanner ::line inc)
;;(if (s/starts-with? comm "&&&")
;;(add-token (update scanner ::line inc) ::token/docstring)
;;(add-token (update scanner ::line inc) ::token/comment))
(recur (advance scanner) (str comm char))))))
(defn- scan-token [scanner]
(let [char (current-char scanner)
scanner (advance scanner)
next (current-char scanner)]
(case char
;; one-character tokens
\( (add-token scanner ::token/lparen)
\) (add-token scanner ::token/rparen)
\{ (add-token scanner ::token/lbrace)
\} (add-token scanner ::token/rbrace)
\[ (add-token scanner ::token/lbracket)
\] (add-token scanner ::token/rbracket)
\; (add-token scanner ::token/semicolon)
\, (add-token scanner ::token/comma)
\newline (add-token (update scanner ::line inc) ::token/newline)
\\ (add-token scanner ::token/backslash)
\= (add-token scanner ::token/equals)
;; two-character tokens
;; ->
\- (cond
(= next \>) (add-token (advance scanner) ::token/rarrow)
(digit? next) (add-number char scanner)
:else (add-error scanner (str "Expected -> or negative number. Got " char next)))
;; at current we're not using this
;; <-
\< (if (= next \-)
(add-token (advance scanner) ::token/larrow)
(add-error scanner (str "Expected <-. Got " char next)))
;; |>
;; Consider => , with =>> for bind
\| (if (= next \>)
(add-token (advance scanner) ::token/pipeline)
(add-error scanner (str "Expected |>. Got " char next)))
;; possible additional operator: bind/result
;; possible additional operator: bind/some
;; oh god, monads
;; additional arrow possibilities: >> ||> ~> => !>
;; hashmap #{
\# (if (= next \{)
(add-token (advance scanner) ::token/starthash)
(add-error scanner (str "Expected beginning of hash: #{. Got " char next)))
;; set ${
\$ (if (= next \{)
(add-token (advance scanner) ::token/startset)
(add-error scanner (str "Expected beginning of set: ${. Got " char next)))
;; placeholders
;; there's a flat _, and then ignored words
\_ (cond
(terminates? next) (add-token scanner ::token/placeholder)
(alpha? next) (add-ignored scanner)
:else (add-error scanner (str "Expected placeholder: _. Got " char next)))
;; comments
;; & starts an inline comment
;; TODO: include comments in scanned file
;; TODO: add doc comments: &&&
\& (add-comment char scanner)
;; keywords
;; TODO: instead of a separate token, scan a whole type keyword
;; e.g. ::string, ::number
\: (cond
;;(= \: next) (add-token (advance scanner) ::token/doublecolon))
(alpha? next) (add-keyword scanner)
:else (add-error scanner (str "Expected keyword. Got " char next)))
;; splats
\. (let [after_next (current-char (advance scanner))]
(if (= ".." (str next after_next))
(add-token (advance (advance scanner)) ::token/splat)
(add-error scanner (str "Expected splat: ... . Got " (str "." next after_next)))))
;; strings
\" (add-string scanner)
;; word matches
(cond
(whitespace? char) scanner ;; for now just skip whitespace characters
(digit? char) (add-number char scanner)
(alpha? char) (add-word char scanner)
:else (add-error scanner (str "Unexpected character: " char))))))
(defn- next-token [scanner]
(assoc scanner ::start (::current scanner)))
(defn scan [source]
(loop [scanner (new-scanner source)]
(if (at-end? scanner)
(let [scanner (add-token scanner ::token/eof)]
{:tokens (::tokens scanner)
:errors (::errors scanner)})
(recur (-> scanner (scan-token) (next-token))))))
(do
(def source "abc nil")
(pp/pprint (scan source)))

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src/ludus/token.clj Normal file
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(ns ludus.token)
(defn token
([type text]
(token type text nil 1))
([type text literal line start]
{::type type
::lexeme text
::literal literal
::line line
::start start}))

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src/parser.janet
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41
src/prelude.janet
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(import /src/base :as b)
(import /src/scanner :as s)
(import /src/parser :as p)
(import /src/validate :as v)
(import /src/interpreter :as i)
(import /src/errors :as e)
(def pkg (do
(def pre-ctx @{:^parent {"base" b/base}})
(def pre-src (slurp "prelude.ld"))
(def pre-scanned (s/scan pre-src :prelude))
(def pre-parsed (p/parse pre-scanned))
(def parse-errors (pre-parsed :errors))
(when (any? parse-errors) (each err parse-errors (e/parse-error err)) (break :error))
(def pre-validated (v/valid pre-parsed pre-ctx))
(def validation-errors (pre-validated :errors))
(when (any? validation-errors) (each err validation-errors (e/validation-error err)) (break :error))
(try
(i/interpret (pre-parsed :ast) pre-ctx)
([err] (e/runtime-error err) :error))))
(def ctx (do
(def ctx @{})
(each [k v] (pairs pkg)
(set (ctx (string k)) v))
(set (ctx "^name") nil)
(set (ctx "^type") nil)
ctx))
(def post/src (slurp "postlude.ld"))
(def post/ast (do
(def post-ctx @{:^parent ctx})
(def post-scanned (s/scan post/src :postlude))
(def post-parsed (p/parse post-scanned))
(def parse-errors (post-parsed :errors))
(when (any? parse-errors) (each err parse-errors (e/parse-error err)) (break :error))
(def post-validated (v/valid post-parsed post-ctx))
(def validation-errors (post-validated :errors))
(when (any? validation-errors) (each err validation-errors (e/validation-error err)) (break :error))
(post-parsed :ast)))

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src/project.janet
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(declare-project
:dependencies [
{:url "https://github.com/ianthehenry/judge.git"
:tag "v2.8.1"}
{:url "https://github.com/janet-lang/spork"}
])
(declare-source
:source ["ludus.janet"])

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src/scanner.janet
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(def reserved-words
"List of Ludus reserved words."
## see ludus-spec repo for more info
{
"as" :as ## impl
"box" :box
"do" :do ## impl
"else" :else ## impl
"false" :false ## impl -> literal word
"fn" :fn ## impl
"if" :if ## impl
"import" :import ## impl
"let" :let ## impl
"loop" :loop ## impl
"match" :match ## impl
"nil" :nil ## impl -> literal word
"ns" :ns ## impl
"panic!" :panic ## impl (should _not_ be a function)
"pkg" :pkg
"recur" :recur ## impl
"repeat" :repeat ## impl
"test" :test
"then" :then ## impl
"true" :true ## impl -> literal word
"use" :use ## wip
"when" :when ## impl, replaces cond
"with" :with ## impl
})
(def literal-words {"true" true
"false" false
"nil" nil
})
(defn- new-scanner
"Creates a new scanner."
[source input]
@{:source source
:input input
:length (length source)
:errors @[]
:start 0
:current 0
:line 1
:tokens @[]})
(defn- at-end?
"Tests if a scanner is at end of input."
[scanner]
(>= (get scanner :current) (get scanner :length)))
(defn- current-char
"Gets the current character of the scanner."
[scanner]
(let [source (get scanner :source)
current (get scanner :current)
length (length source)]
(if (>= current length)
nil
(string/from-bytes (get source current)))))
(defn- advance
"Advances the scanner by a single character."
[scanner]
(update scanner :current inc))
(defn- next-char
"Gets the next character from the scanner."
[scanner]
(let [source (get scanner :source)
current (get scanner :current)
next (inc current)
length (length source)]
(if (>= next length)
nil
(string/from-bytes (get source next)))))
(defn- current-lexeme
[scanner]
(slice (get scanner :source) (get scanner :start) (get scanner :current)))
(defn- char-code [char] (get char 0))
(defn- char-in-range? [start end char]
(and char
(>= (char-code char) (char-code start))
(<= (char-code char) (char-code end))))
(defn- digit? [c]
(char-in-range? "0" "9" c))
(defn- nonzero-digit? [c]
(char-in-range? "1" "9" c))
## for now, use very basic ASCII charset in words
## TODO: research the implications of using the whole
## (defn- alpha? [c] (boolean (re-find #"\p{L}" (string c))))
(defn- alpha? [c]
(or (char-in-range? "a" "z" c) (char-in-range? "A" "Z" c)))
(defn- lower? [c] (char-in-range? "a" "z" c))
(defn- upper? [c] (char-in-range? "A" "Z" c))
## legal characters in words
(def word-chars {"_" true "?" true "!" true "*" true "/" true})
(defn- word-char? [c]
(or (alpha? c) (digit? c) (get word-chars c)))
(defn- whitespace? [c]
(or (= c " ") (= c "\t")))
(def terminators {
":" true
";" true
"\n" true
"{" true
"}" true
"(" true
")" true
"[" true
"]" true
"$" true
"#" true
"-" true
"=" true
"&" true
"," true
">" true
"\"" true})
(defn- terminates? [c]
(or (nil? c) (whitespace? c) (get terminators c)))
(defn- add-token
[scanner token-type &opt literal]
(update scanner :tokens array/push
{:type token-type
:lexeme (current-lexeme scanner)
:literal literal
:line (get scanner :line)
:start (get scanner :start)
:source (get scanner :source)
:input (get scanner :input)}))
## TODO: errors should also be in the vector of tokens
## The goal is to be able to be able to hand this to an LSP?
## Do we need a different structure
(defn- add-error [scanner msg]
(let [token {:type :error
:lexeme (current-lexeme scanner)
:literal nil
:line (get scanner :line)
:start (get scanner :start)
:source (get scanner :source)
:input (get scanner :input)
:msg msg}]
(-> scanner
(update :errors array/push token)
(update :tokens array/push token))))
(defn- add-keyword
[scanner]
(defn recur [scanner key]
(let [char (current-char scanner)]
(cond
(terminates? char) (add-token scanner :keyword (keyword key))
(word-char? char) (recur (advance scanner) (string key char))
:else (add-error scanner (string "Unexpected " char "after keyword :" key)))))
(recur scanner ""))
(defn- add-pkg-kw [scanner]
(defn recur [scanner key]
(let [char (current-char scanner)]
(cond
(terminates? char) (add-token scanner :pkg-kw (keyword key))
(word-char? char) (recur (advance scanner) (string key char))
:else (add-error scanner (string "Unexpected " char " after pkg keyword :" key)))))
(recur scanner ""))
(defn- read-literal [lit] (-> lit parse-all first))
### TODO: consider whether Janet's number rules are right for Ludus
(defn- add-number [char scanner]
(defn recur [scanner num float?]
(let [curr (current-char scanner)]
(cond
(= curr "_") (recur (advance scanner) num float?) ## consume underscores unharmed
(= curr ".") (if float?
(add-error scanner (string "Unexpected second decimal point after " num "."))
(recur (advance scanner) (buffer/push num curr) true))
(terminates? curr) (add-token scanner :number (read-literal num))
(digit? curr) (recur (advance scanner) (buffer/push num curr) float?)
:else (add-error scanner (string "Unexpected " curr " after number " num ".")))))
(recur scanner (buffer char) false))
(def escape {
"\"" "\""
"n" "\n"
"{" "{"
"t" "\t"
"r" "\r"
"\\" "\\"
})
(defn- add-string
[scanner]
(defn recur [scanner buff interpolate?]
(let [char (current-char scanner)]
(case char
"{" (recur (advance scanner) (buffer/push buff char) true)
# allow multiline strings
"\n" (recur (update (advance scanner) :line inc) (buffer/push buff char) interpolate?)
"\"" (add-token (advance scanner) (if interpolate? :interpolated :string) (string buff))
"\\" (let [next (next-char scanner)]
(recur
(advance (advance scanner))
(buffer/push buff (get escape next next))
interpolate?))
(if (at-end? scanner)
(add-error scanner "Unterminated string.")
(recur (advance scanner) (buffer/push buff char) interpolate?)))))
(recur scanner @"" false))
(defn- add-word
[char scanner]
(defn recur [scanner word]
(let [curr (current-char scanner)]
(cond
(terminates? curr) (add-token scanner
(get reserved-words (string word) :word)
(get literal-words (string word) :none))
(word-char? curr) (recur (advance scanner) (buffer/push word curr))
:else (add-error scanner (string "Unexpected " curr " after word " word ".")))))
(recur scanner (buffer char)))
(defn- add-pkg
[char scanner]
(defn recur [scanner pkg]
(let [curr (current-char scanner)]
(cond
(terminates? curr) (add-token scanner :pkg-name :none)
(word-char? curr) (recur (advance scanner) (buffer/push pkg curr))
:else (add-error scanner (string "unexpected " curr " after pkg name " pkg)))))
(recur scanner (buffer char)))
(defn- add-ignored
[scanner]
(defn recur [scanner ignored]
(let [char (current-char scanner)]
(cond
(terminates? char) (add-token scanner :ignored)
(word-char? char) (recur (advance scanner) (buffer/push ignored char))
:else (add-error scanner (string "Unexpected " char " after word " ignored ".")))))
(recur scanner @"_"))
(defn- add-comment [char scanner]
(defn recur [scanner comm]
(let [char (current-char scanner)]
(if (or (= "\n" char) (at-end? scanner))
scanner # for now, we don't do anything with comments; can be added later
(recur (advance scanner) (buffer/push comm char)))))
(recur scanner (buffer char)))
(defn- scan-token [scanner]
(let [char (current-char scanner)
scanner (advance scanner)
next (current-char scanner)]
(case char
## one-character tokens
## :break is a special zero-char token before closing braces
## it makes parsing much simpler
"(" (add-token scanner :lparen)
")" (add-token (add-token scanner :break) :rparen)
"{" (add-token scanner :lbrace)
"}" (add-token (add-token scanner :break) :rbrace)
"[" (add-token scanner :lbracket)
"]" (add-token (add-token scanner :break) :rbracket)
";" (add-token scanner :semicolon)
"," (add-token scanner :comma)
"\n" (add-token (update scanner :line inc) :newline)
"\\" (add-token scanner :backslash)
"=" (add-token scanner :equals)
">" (add-token scanner :pipeline)
## two-character tokens
## ->
"-" (cond
(= next ">") (add-token (advance scanner) :arrow)
(digit? next) (add-number char scanner)
:else (add-error scanner (string "Expected > or negative number after `-`. Got `" char next "`")))
## dict #{
"#" (if (= next "{")
(add-token (advance scanner) :startdict)
(add-error scanner (string "Expected beginning of dict: #{. Got " char next)))
## set ${
"$" (if (= next "{")
(add-token (advance scanner) :startset)
(add-error scanner (string "Expected beginning of set: ${. Got " char next)))
## placeholders
## there's a flat _, and then ignored words
"_" (cond
(terminates? next) (add-token scanner :placeholder)
(alpha? next) (add-ignored scanner)
:else (add-error scanner (string "Expected placeholder: _. Got " char next)))
## comments
## & starts an inline comment
"&" (add-comment char scanner)
## keywords
# XXX: make sure we want only lower-only keywords
":" (cond
(lower? next) (add-keyword scanner)
(upper? next) (add-pkg-kw scanner)
:else (add-error scanner (string "Expected keyword or pkg keyword. Got " char next)))
## splats
"." (let [after_next (current-char (advance scanner))]
(if (= ".." (string next after_next))
(add-token (advance scanner) :splat)
(add-error scanner (string "Expected splat: ... . Got " (string "." next after_next)))))
## strings
"\"" (add-string scanner)
## word matches
(cond
(whitespace? char) scanner ## for now just skip whitespace characters
(digit? char) (add-number char scanner)
(upper? char) (add-pkg char scanner)
(lower? char) (add-word char scanner)
:else (add-error scanner (string "Unexpected character: " char))))))
(defn- next-token [scanner]
(put scanner :start (get scanner :current)))
(defn scan [source &opt input]
(default input :input)
(defn recur [scanner]
(if (at-end? scanner)
(let [scanner (add-token (add-token scanner :break) :eof)]
{:tokens (get scanner :tokens)
:errors (get scanner :errors [])})
(recur (-> scanner (scan-token) (next-token)))))
(recur (new-scanner source input)))
(comment
# (do
(def source "add 1 2 () four")
(scan source)
)

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src/validate.janet
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### A validator for a Ludus AST
(comment
Tracking here, before I start writing this code, the kinds of validation we're hoping to accomplish:
* [x] ensure called keywords are only called w/ one arg
* [x] first-level property access with pkg, e.g. `Foo :bar`--bar must be on Foo
- [x] accept pkg-kws
* [x] validate dict patterns
* [x] compile string-patterns
* [x] `loop` form arity checking
* [x] arity checking of explicit named function calls
* [x] flag tail calls
* [x] no re-bound names
* [x] no unbound names
* [x] no unbound names with `use` forms
* [x] recur in tail position in `loop` forms
* [x] recur not called outside of `loop` forms
* [x] splats come at the end of list, tuple, and dict patterns
Deferred until a later iteration of Ludus:
* [ ] no circular imports DEFERRED
* [ ] correct imports DEFERRED
* [ ] validate `with` forms
)
(def- package-registry @{})
# (try (os/cd "janet") ([_] nil))
(import ./scanner :as s)
(import ./parser :as p)
(defn- new-validator [parser]
(def ast (parser :ast))
@{:ast ast
:errors @[]
:ctx @{}
:status @{}}
)
(var validate nil)
(def terminals [:number :string :bool :nil :placeholder])
(def simple-colls [:list :tuple :set :args])
(defn- simple-coll [validator]
(def ast (validator :ast))
(def data (ast :data))
(each node data
(set (validator :ast) node)
(validate validator))
validator)
(defn- iff [validator]
(def ast (validator :ast))
(def data (ast :data))
(each node data
(set (validator :ast) node)
(validate validator))
validator)
(defn- script [validator]
(def ast (validator :ast))
(def data (ast :data))
(def status (validator :status))
(set (status :toplevel) true)
(each node data
(set (validator :ast) node)
(validate validator))
validator)
(defn- block [validator]
(def ast (validator :ast))
(def data (ast :data))
(when (= 0 (length data))
(array/push (validator :errors)
{:node ast :msg "blocks may not be empty"})
(break validator))
(def status (validator :status))
(set (status :toplevel) nil)
(def tail? (status :tail))
(set (status :tail) false)
(def parent (validator :ctx))
(def ctx @{:^parent parent})
(set (validator :ctx) ctx)
(for i 0 (-> data length dec)
(set (validator :ast) (data i))
(validate validator))
(set (status :tail) tail?)
(set (validator :ast) (last data))
(validate validator)
(set (validator :ctx) parent)
validator)
(defn- resolve-local [ctx name]
(get ctx name))
(defn- resolve-name [ctx name]
(when (nil? ctx) (break nil))
(def node (get ctx name))
(if node node (resolve-name (get ctx :^parent) name)))
(defn- resolve-name-in-script [ctx name]
(when (ctx :^toplevel) (break nil))
(def node (ctx name))
(if node node (resolve-name-in-script (ctx :^parent) name)))
(defn- word [validator]
(def ast (validator :ast))
(def name (ast :data))
(def ctx (validator :ctx))
(def resolved (resolve-name ctx name))
(when (not resolved)
(array/push (validator :errors)
{:node ast :msg "unbound name"}))
validator)
### patterns
(var pattern nil)
(defn- lett [validator]
(def ast (validator :ast))
(def [lhs rhs] (ast :data))
# evaluate the expression first
# otherwise lhs names will appear bound
(set (validator :ast) rhs)
(validate validator)
(set (validator :ast) lhs)
(pattern validator)
validator)
(defn- splattern [validator]
(def ast (validator :ast))
(def status (validator :status))
(when (not (status :last))
(array/push (validator :errors)
{:node ast :msg "splats may only come last in collection patterns"}))
(def data (ast :data))
(when data
(set (validator :ast) data)
(pattern validator))
validator)
(defn- simple-coll-pattern [validator]
(def ast (validator :ast))
(def data (ast :data))
(when (empty? data) (break validator))
(def status (validator :status))
(for i 0 (-> data length dec)
(set (validator :ast) (get data i))
(pattern validator))
(set (status :last) true)
(set (validator :ast) (last data))
(pattern validator)
(set (status :last) nil)
validator)
(defn- word-pattern [validator]
(def ast (validator :ast))
(def name (ast :data))
(def ctx (validator :ctx))
### XXX TODO: this resolution should ONLY be for userspace, NOT prelude
(def resolved (resolve-name-in-script ctx name))
(when resolved
(def {:line line :input input} resolved)
(array/push (validator :errors)
{:node ast :msg (string "name " name " is already bound on line "
line " of " input)}))
(set (ctx name) ast)
# (pp ctx)
validator)
(def types [
:nil
:bool
:number
:keyword
:string
:set
:tuple
:dict
:list
:fn
:box
:pkg
])
(defn typed [validator]
(def ast (validator :ast))
(def [kw-type word] (ast :data))
(def type (kw-type :data))
(when (not (has-value? types type))
(array/push (validator :errors)
{:node kw-type :msg "unknown type"}))
(set (validator :ast) word)
(pattern validator))
(defn- str-pattern [validator]
(def ast (validator :ast))
(def data (ast :data))
(def last-term (-> data array/pop string))
(def grammar @{})
(def bindings @[])
(var current 0)
(each node data
(when (not (buffer? node))
(set (validator :ast) node)
(pattern validator))
(if (buffer? node)
(set (grammar (keyword current)) (string node))
(do
(set (grammar (keyword current))
~(<- (to ,(keyword (inc current)))))
(array/push bindings (node :data))))
(set current (inc current)))
(set (grammar (keyword current)) ~(* ,last-term -1))
(def rules (map keyword (range (length grammar))))
(set (grammar :main) ~(* ,;rules))
(set (ast :grammar) grammar)
(set (ast :compiled) (peg/compile grammar))
(set (ast :bindings) bindings))
(defn- pair [validator]
(def ast (validator :ast))
(def [_ patt] (ast :data))
(set (validator :ast) patt)
(pattern validator))
(defn- pattern* [validator]
# (print "PATTERN*")
(def ast (validator :ast))
(def type (ast :type))
# (print "validating pattern " type)
(cond
(has-value? terminals type) validator
(case type
:word (word-pattern validator)
:placeholder validator
:ignored validator
:word (word-pattern validator)
:list (simple-coll-pattern validator)
:tuple (simple-coll-pattern validator)
:dict (simple-coll-pattern validator)
:splat (splattern validator)
:typed (typed validator)
:interpolated (str-pattern validator)
:pair (pair validator)
)))
(set pattern pattern*)
# XXX: ensure guard includes only allowable names
# XXX: what to include here? (cf Elixir)
(defn- guard [validator])
(defn- match-clauses [validator clauses]
# (print "validating clauses in match-clauses")
(each clause clauses
(def parent (validator :ctx))
(def ctx @{:^parent parent})
(set (validator :ctx) ctx)
(def [lhs guard rhs] clause)
(set (validator :ast) lhs)
(pattern validator)
# (pp (validator :ctx))
# (pp (validator :ctx))
(when guard
(set (validator :ast) guard)
(validate validator))
(set (validator :ast) rhs)
(validate validator)
(set (validator :ctx) parent)))
(defn- matchh [validator]
# (print "validating in matchh")
(def ast (validator :ast))
(def [to-match clauses] (ast :data))
# (print "validating expression:")
# (pp to-match)
(set (validator :ast) to-match)
(validate validator)
# (print "validating clauses")
(match-clauses validator clauses)
validator)
(defn- declare [validator fnn]
(def status (validator :status))
(def declared (get status :declared @{}))
(set (declared fnn) true)
(set (status :declared) declared)
# (print "declared function " (fnn :name))
# (pp declared)
validator)
(defn- define [validator fnn]
(def status (validator :status))
(def declared (get status :declared @{}))
(set (declared fnn) nil)
(set (status :declared) declared)
# (print "defined function " (fnn :name))
# (pp declared)
validator)
(defn- fnn [validator]
(def ast (validator :ast))
(def name (ast :name))
# (print "function name: " name)
(def status (validator :status))
(def tail? (status :tail))
(set (status :tail) true)
(when name
(def ctx (validator :ctx))
(def resolved (ctx name))
(when (and resolved (not= :nothing (resolved :data)))
(def {:line line :input input} (get-in ctx [name :token]))
(array/push (validator :errors)
{:node ast :msg (string "name is already bound on line " line " of " input)}))
(when (and resolved (= :nothing (resolved :data)))
(define validator resolved))
(set (ctx name) ast))
(def data (ast :data))
(when (= data :nothing)
(break (declare validator ast)))
(match-clauses validator data)
(set (status :tail) tail?)
(def rest-arities @{})
(def arities @{:rest rest-arities})
(each clause data
# (print "CLAUSE:")
# (pp clause)
(def patt (first clause))
(def params (patt :data))
(def arity (length params))
# (print "checking clause with arity " arity)
(def rest-param? (and (> arity 0) (= :splat ((last params) :type))))
(if rest-param?
(set (rest-arities arity) true)
(set (arities arity) true)))
# (pp arities)
(set (ast :arities) arities)
validator)
(defn- box [validator]
(def ast (validator :ast))
(def ctx (validator :ctx))
(def expr (ast :data))
(set (validator :ast) expr)
(validate validator)
(def name (ast :name))
(def resolved (ctx name))
(when resolved
(def {:line line :input input} (get-in ctx [name :token]))
(array/push (validator :errors)
{:node ast :msg (string "name is already bound on line " line " of " input)}))
(set (ctx name) ast)
validator)
(defn- interpolated [validator]
(def ast (validator :ast))
(def data (ast :data))
(each node data
(when (not (buffer? node))
(set (validator :ast) node)
(validate validator))))
### TODO:
# * [ ] ensure properties are on pkgs (if *only* pkgs from root)
(defn- pkg-root [validator]
# (print "validating pkg-root access")
(def ast (validator :ast))
(def ctx (validator :ctx))
(def terms (ast :data))
(def pkg-name ((first terms) :data))
(def the-pkg (resolve-name ctx pkg-name))
(when (not the-pkg)
(array/push (validator :errors)
{:node ast :msg "unbound pkg name"})
(break validator))
(def member (get terms 1))
(def accessed (case (member :type)
:keyword (get-in the-pkg [:pkg (member :data)])
:pkg-kw (get-in the-pkg [:pkg (member :data)])
:args (do
(array/push (validator :errors)
{:node member :msg "cannot call a pkg"}
(break validator)))))
(when (not accessed)
# (print "no member " (member :data) " on " pkg-name)
(array/push (validator :errors)
{:node member :msg "invalid pkg access"})
(break validator))
# TODO: validate nested pkg access
)
# (defn- tail-call [validator]
# (def ast (validator :ast))
# (when (ast :partial) (break validator))
# (def status (validator :status))
# (when (not (status :tail)) (break validator))
# (def data (ast :data))
# (def args (last data))
# (set (args :tail-call) true))
(defn- check-arity [validator]
# (print "CHECKING ARITY")
(def ast (validator :ast))
# (when (ast :partial) (break validator))
(def ctx (validator :ctx))
(def data (ast :data))
(def fn-word (first data))
# (pp fn-word)
(def the-fn (resolve-name ctx (fn-word :data)))
# (print "the called function: " the-fn)
# (pp the-fn)
(when (not the-fn) (break validator))
# (print "the function is not nil")
# (print "the function type is " (type the-fn))
(when (= :function (type the-fn)) (break validator))
(when (= :cfunction (type the-fn)) (break validator))
# (print "the function is not a janet fn")
# (print "fn type: " (the-fn :type))
(when (not= :fn (the-fn :type)) (break validator))
# (print "fn name: " (the-fn :name))
(def arities (the-fn :arities))
# when there aren't arities yet, break, since that means we're making a recursive function call
# TODO: enahnce this so that we can determine arities *before* all function bodies; this ensures arity-checking for self-recursive calls
(when (not arities) (break validator))
# (print "arities: ")
# (pp arities)
(def args (get data 1))
(def num-args (length (args :data)))
# (print "called with #args " num-args)
# (pp (get (validator :ctx) "bar"))
(when (has-key? arities num-args) (break validator))
# (print "arities: ")
# (pp arities)
(when (not arities) (break validator))
(def rest-arities (keys (arities :rest)))
(when (empty? rest-arities)
(array/push (validator :errors)
{:node ast :msg "wrong number of arguments"})
(break validator))
(def rest-min (min ;rest-arities))
(when (< num-args rest-min)
(array/push (validator :errors)
{:node ast :msg "wrong number of arguments"}))
validator)
(defn- kw-root [validator]
(def ast (validator :ast))
(def data (ast :data))
(def [_ args] data)
(when (not= :args (args :type))
(break (array/push (validator :errors)
{:node args :msg "called keyword expects an argument"})))
(when (not= 1 (length (args :data)))
(array/push (validator :errors)
{:node args :msg "called keywords take one argument"})))
(defn- synthetic [validator]
(def ast (validator :ast))
(def data (ast :data))
(def status (validator :status))
(def ftype ((first data) :type))
(def stype ((get data 1) :type))
(def ltype ((last data) :type))
(set (status :pkg-access?) nil)
(when (= ftype :pkg-name)
(set (status :pkg-access?) true))
(each node data
(set (validator :ast) node)
(validate validator))
(set (validator :ast) ast)
# (print "ftype " ftype)
# (print "stype " stype)
# (print "ltype " ltype)
(when (= ftype :pkg-name) (pkg-root validator))
(when (= ftype :keyword) (kw-root validator))
# (when (= ltype :args) (tail-call validator))
(when (and (= ftype :word) (= stype :args))
(check-arity validator))
validator)
(defn- pair [validator]
(def ast (validator :ast))
(def [k v] (ast :data))
(set (validator :ast) k)
(validate validator)
(set (validator :ast) v)
(validate validator))
(defn- splat [validator]
(def ast (validator :ast))
(when (get-in validator [:status :pkg])
(array/push (validator :errors)
{:node ast :msg "splats are not allowed in pkgs"})
(break validator))
(def data (ast :data))
(when data
(set (validator :ast) data)
(validate validator))
validator)
(defn- dict [validator]
(def ast (validator :ast))
(def data (ast :data))
(each node data
(set (validator :ast) node)
(validate validator))
validator)
(defn- whenn [validator]
(def ast (validator :ast))
(def data (ast :data))
(each node data
(def [lhs rhs] node)
(set (validator :ast) lhs)
(validate validator)
(set (validator :ast) rhs)
(validate validator))
validator)
# XXX: do this!
(defn- withh [validator])
# XXX: tail calls in last position
(defn- doo [validator]
(def ast (validator :ast))
(def data (ast :data))
(each node data
(set (validator :ast) node)
(validate validator))
validator)
(defn- usee [validator]
(def ast (validator :ast))
(def data (ast :data))
(set (validator :ast) data)
(validate validator)
(def name (data :data))
(def ctx (validator :ctx))
(def pkg (get-in ctx [name :pkg] @{}))
(loop [[k v] :pairs pkg]
(set (ctx (string k)) v))
validator)
(defn- pkg-entry [validator pkg]
(def ast (validator :ast))
(def status (validator :status))
(when (= :pkg-pair (ast :type))
(set (status :pkg-access?) true))
(def data (ast :data))
(def [key value] (ast :data))
# (print "PKG ENTRY***")
# (pp key)
# (pp value)
(set (validator :ast) key)
(validate validator)
(set (validator :ast) value)
(validate validator)
(def entry (if (= :pkg-name (value :type))
(resolve-name (validator :ctx) (string (value :data)))
value))
# (print "entry at " (key :data))
# (pp entry)
(set (status :pkg-access?) nil)
(def kw (key :data))
# (pp kw)
(set (pkg kw) entry)
# (pp pkg)
validator)
(defn- pkg [validator]
(def ast (validator :ast))
(def data (ast :data))
(def name (ast :name))
(def pkg @{})
(each node data
(set (validator :ast) node)
(pkg-entry validator pkg))
(set (ast :pkg) pkg)
# (print "THE PACKAGE")
# (pp pkg)
(def ctx (validator :ctx))
(set (ctx name) ast)
validator)
(defn- ns [validator]
(def ast (validator :ast))
(def data (ast :data))
(def name (ast :name))
(def parent (validator :ctx))
(def ctx @{:^parent parent})
(def block (data :data))
(each node block
(set (validator :ast) node)
(validate validator))
(set (ast :pkg) ctx)
(set (parent name) ast)
validator)
(defn- loopp [validator]
(def ast (validator :ast))
(def status (validator :status))
(def data (ast :data))
(def input (first data))
# (print "LOOP INPUT")
# (pp input)
(def clauses (get data 1))
(def input-arity (length (input :data)))
(set (ast :arity) input-arity)
# (print "input arity to loop " input-arity)
(set (validator :ast) input)
(validate validator)
# harmonize arities
(def rest-arities @{})
(each clause clauses
# (print "CLAUSE:")
# (pp clause)
(def patt (first clause))
(def params (patt :data))
(def clause-arity (length params))
# (print "checking clause with arity " clause-arity)
(def rest-param? (= :splat (get (last params) :type)))
(when (and
(not rest-param?) (not= clause-arity input-arity))
(array/push (validator :errors)
{:node patt :msg "arity mismatch"}))
(when rest-param?
(set (rest-arities clause-arity) patt)))
# (pp rest-arities)
(loop [[arity patt] :pairs rest-arities]
(when (< input-arity arity)
(array/push (validator :errors)
{:node patt :msg "arity mismatch"})))
(def loop? (status :loop))
(set (status :loop) input-arity)
(def tail? (status :tail))
(set (status :tail) true)
(match-clauses validator clauses)
(set (status :loop) loop?)
(set (status :tail) tail?)
validator)
(defn- recur [validator]
(def ast (validator :ast))
(def status (validator :status))
(def loop-arity (status :loop))
(when (not loop-arity)
(array/push (validator :errors)
{:node ast :msg "recur may only be used inside a loop"})
(break validator))
(def called-with (get-in ast [:data :data]))
(def recur-arity (length called-with))
# (print "loop arity " loop-arity)
# (print "recur arity" recur-arity)
(when (not= recur-arity loop-arity)
(array/push (validator :errors)
{:node ast :msg "recur must have the same number of args as its loop"}))
(when (not (status :tail))
(array/push (validator :errors)
{:node ast :msg "recur must be in tail position"}))
(set (validator :ast) (ast :data))
(validate validator))
(defn- repeatt [validator]
(def ast (validator :ast))
(def [times body] (ast :data))
(set (validator :ast) times)
(validate validator)
(set (validator :ast) body)
(validate validator))
(defn- panic [validator]
(def ast (validator :ast))
(def data (ast :data))
(set (validator :ast) data)
(validate validator))
(defn- testt [validator]
(def ast (validator :ast))
(def [_ body] (ast :data))
(set (validator :ast) body)
(validate validator))
(defn- pkg-name [validator]
(def ast (validator :ast))
(def name (ast :data))
(def ctx (validator :ctx))
(def pkg (resolve-name ctx name))
(when (not pkg)
(array/push (validator :errors)
{:node ast :msg "unbound name"}))
validator)
(defn- pkg-kw [validator]
# (print "validating pkg-kw")
(def ast (validator :ast))
(def pkg-access? (get-in validator [:status :pkg-access?]))
# (print "pkg-access? " pkg-access?)
(when (not pkg-access?)
(array/push (validator :errors)
{:node ast :msg "cannot use pkg-kw here"}))
validator)
(defn- pkg-pair [validator]
# (print "validating pkg-pair")
(def ast (validator :ast))
(def status (validator :status))
(def [_ pkg] (ast :data))
(set (status :pkg-access?) true)
(set (validator :ast) pkg)
(validate validator)
(set (status :pkg-access?) nil)
validator)
(defn- kw [validator]
(def status (validator :status))
(set (status :pkg-access?) nil)
validator)
(defn- validate* [validator]
(def ast (validator :ast))
(def type (ast :type))
# (print "validating node " type)
(cond
(has-value? terminals type) validator
(has-value? simple-colls type) (simple-coll validator)
(case type
:keyword (kw validator)
:if (iff validator)
:let (lett validator)
:script (script validator)
:block (block validator)
:word (word validator)
:fn (fnn validator)
:match (matchh validator)
:interpolated (interpolated validator)
:synthetic (synthetic validator)
:do (doo validator)
:dict (dict validator)
:test (testt validator)
:panic (panic validator)
:repeat (repeatt validator)
:when (whenn validator)
:splat (splat validator)
:pair (pair validator)
:pkg-pair (pkg-pair validator)
:ns (ns validator)
:pkg (pkg validator)
:pkg-name (pkg-name validator)
:pkg-kw (pkg-kw validator)
:use (usee validator)
:loop (loopp validator)
:recur (recur validator)
:box (box validator)
(error (string "unknown node type " type)))))
(set validate validate*)
(defn- cleanup [validator]
(def declared (get-in validator [:status :declared] {}))
(when (any? declared)
(each declaration declared
(array/push (validator :errors) {:node declaration :msg "declared fn, but not defined"})))
validator)
(defn valid [ast &opt ctx]
(default ctx @{})
(set (ctx :^toplevel) true)
(def validator (new-validator ast))
(def base-ctx @{:^parent ctx})
(set (validator :ctx) base-ctx)
(validate validator)
(cleanup validator))
(import ./base :as b)
# (do
(comment
(def source `
dec (12)
`)
(def scanned (s/scan source))
(def parsed (p/parse scanned))
(def validated (valid parsed b/ctx))
# (get-in validated [:status :declared])
# (validated :ctx)
)

7
test/cludus/core_test.clj Normal file
View File

@ -0,0 +1,7 @@
(ns cludus.core-test
(:require [clojure.test :refer :all]
[cludus.core :refer :all]))
(deftest a-test
(testing "FIXME, I fail."
(is (= 0 1))))

9
test/judgy.fish
View File

@ -1,9 +0,0 @@
#!/opt/homebrew/bin/fish
set FILE $argv[1]
set TESTFILE (string join "" $FILE ".tested")
judge $FILE
if test -e $TESTFILE
cp $TESTFILE $FILE
rm $TESTFILE
end

371
test/language.test.janet
View File

@ -1,371 +0,0 @@
# testing Ludus langauge constructs
(try (os/cd "janet") ([_] nil)) # for REPL
(import /scanner :as s)
(import /parser :as p)
(import /validate :as v)
(import /interpreter :as i)
(import /errors :as e)
(import /base :as b)
(use judge)
(defn run [source]
(def ctx @{})
(def scanned (s/scan source :test))
(when (any? (scanned :errors))
(e/scan-error (scanned :errors)) (error "scanning errors"))
(def parsed (p/parse scanned))
(when (any? (parsed :errors))
(e/parse-error (parsed :errors)) (error "parsing errors"))
(def valid (v/valid parsed ctx))
(when (any? (valid :errors)) (each err (valid :errors)
(e/validation-error err)) (error "validation errors"))
(i/interpret (parsed :ast) ctx))
(deftest "returns bare values from single-line scripts"
(test (run "true") true)
(test (run "false") false)
(test (run "nil") :^nil)
(test (run "12.34") 12.34)
(test (run "-32") -32)
(test (run "0") 0)
(test (run ":foo") :foo)
(test (run ":bar") :bar)
(test (run `"a string, a text, a language"`) "a string, a text, a language"))
(deftest "returns empty collections from single-line scripts"
(test (run "()") [])
(test (run "#{}") @{})
(test (run "${}") @{:^type :set})
(test (run "[]") @[]))
(deftest "returns populated collections from single-line scripts"
(test (run "(1, 2, 3)") [1 2 3])
(test (run "[:a, :b, :c]") @[:a :b :c])
(test (run "${1, 2, 3, 3}") @{1 true 2 true 3 true :^type :set})
(test (run "#{:a 1, :b 2}") @{:a 1 :b 2}))
(deftest "returns nested collections from single-line scripts"
(test (run "((), (1, 2), [:a, (:b)], #{:foo true, :bar false})")
[[]
[1 2]
@[:a [:b]]
@{:bar false :foo true}])
(test (run `#{:foo #{:bar "thing", :baz (1, :foo, nil)}}`) @{:foo @{:bar "thing" :baz [1 :foo :^nil]}}))
(deftest "binds names in let bindings with various patterns"
(test (run `let foo = :bar; foo`) :bar)
(test (run `let 42 = 42`) 42)
(test (run `let foo = :bar; let quux = 42; (foo, quux)`) [:bar 42])
(test (run `let (:ok, value) = (:ok, 42); value`) 42)
(test (run `let #{:a x, ...} = #{:a 1, :b 2}; x`) 1))
(deftest "executes if/then/else properly"
(test (run `if nil then :foo else :bar`) :bar)
(test (run `if false then :foo else :bar`) :bar)
(test (run `if true then :foo else :bar`) :foo)
(test (run `if 42 then :foo else panic! "oops"`) :foo))
(deftest "panics"
(test-error (run `panic! "oops"`)
{:msg "oops"
:node {:data {:data "oops"
:token {:input :test
:lexeme "\"oops\""
:line 1
:literal "oops"
:source "panic! \"oops\""
:start 7
:type :string}
:type :string}
:token {:input :test
:lexeme "panic!"
:line 1
:literal :none
:source "panic! \"oops\""
:start 0
:type :panic}
:type :panic}})
)
(deftest "no match in let panics"
(test-error (run "let :foo = :bar")
{:msg "no match: let binding"
:node {:data @[{:data :foo
:token {:input :test
:lexeme ":foo"
:line 1
:literal :foo
:source "let :foo = :bar"
:start 4
:type :keyword}
:type :keyword}
{:data :bar
:token {:input :test
:lexeme ":bar"
:line 1
:literal :bar
:source "let :foo = :bar"
:start 11
:type :keyword}
:type :keyword}]
:token {:input :test
:lexeme "let"
:line 1
:literal :none
:source "let :foo = :bar"
:start 0
:type :let}
:type :let}
:value :bar})
)
(deftest "blocks execute code and work"
(test (run `
let bar = 12
let foo = {
let bar = 42
let baz = :quux
:foo
}
(foo, bar)
`)
[:foo 12])
(test (run `
let foo = {
let bar = 12
{
let bar = 15
bar
}
}
`)
15))
(deftest "unbound name panics"
(test-error (run `foo`) "validation errors"))
(deftest "rebinding name panics"
(test-error (run `let foo = 42; let foo = 23`) "validation errors"))
(deftest "when forms work as expected"
(test (run `
when {
false -> :nope
nil -> :nope
12 -> :yes
}
`)
:yes)
(test-error (run `
when {
false -> :nope
nil -> :nope
}
`)
{:msg "no match: when form"
:node {:data @[[{:data false
:token {:input :test
:lexeme "false"
:line 2
:literal false
:source " when {\n false -> :nope\n nil -> :nope\n }\n "
:start 12
:type :false}
:type :bool}
{:data :nope
:token {:input :test
:lexeme ":nope"
:line 2
:literal :nope
:source " when {\n false -> :nope\n nil -> :nope\n }\n "
:start 21
:type :keyword}
:type :keyword}]
[{:token {:input :test
:lexeme "nil"
:line 3
:literal :none
:source " when {\n false -> :nope\n nil -> :nope\n }\n "
:start 30
:type :nil}
:type :nil}
{:data :nope
:token {:input :test
:lexeme ":nope"
:line 3
:literal :nope
:source " when {\n false -> :nope\n nil -> :nope\n }\n "
:start 37
:type :keyword}
:type :keyword}]]
:token {:input :test
:lexeme "when"
:line 1
:literal :none
:source " when {\n false -> :nope\n nil -> :nope\n }\n "
:start 2
:type :when}
:type :when}})
)
(deftest "match forms work as expected"
(test (run `
match :foo with {
:bar -> :nope
:baz -> :nope
x -> x
}
`)
:foo)
(test (run `
let foo = 42
match (:ok, foo) with {
(:err, _) -> :nope
(:ok, :foo) -> :nope
(:ok, _) -> :yes
}
`)
:yes)
(test-error (run `
let foo = "foo"
match foo with {
"bar" -> :nope
"baz" -> :nope
12.34 -> :nope
}
`)
{:msg "no match: match form"
:node @{:data [{:data "foo"
:token {:input :test
:lexeme "foo"
:line 2
:literal :none
:source " let foo = \"foo\"\n match foo with {\n \"bar\" -> :nope\n \"baz\" -> :nope\n 12.34 -> :nope \n }\n "
:start 26
:type :word}
:type :word}
@[[{:data "bar"
:token {:input :test
:lexeme "\"bar\""
:line 3
:literal "bar"
:source " let foo = \"foo\"\n match foo with {\n \"bar\" -> :nope\n \"baz\" -> :nope\n 12.34 -> :nope \n }\n "
:start 40
:type :string}
:type :string}
nil
{:data :nope
:token {:input :test
:lexeme ":nope"
:line 3
:literal :nope
:source " let foo = \"foo\"\n match foo with {\n \"bar\" -> :nope\n \"baz\" -> :nope\n 12.34 -> :nope \n }\n "
:start 49
:type :keyword}
:type :keyword}]
[{:data "baz"
:token {:input :test
:lexeme "\"baz\""
:line 4
:literal "baz"
:source " let foo = \"foo\"\n match foo with {\n \"bar\" -> :nope\n \"baz\" -> :nope\n 12.34 -> :nope \n }\n "
:start 58
:type :string}
:type :string}
nil
{:data :nope
:token {:input :test
:lexeme ":nope"
:line 4
:literal :nope
:source " let foo = \"foo\"\n match foo with {\n \"bar\" -> :nope\n \"baz\" -> :nope\n 12.34 -> :nope \n }\n "
:start 67
:type :keyword}
:type :keyword}]
[{:data 12.34
:token {:input :test
:lexeme "12.34"
:line 5
:literal 12.34
:source " let foo = \"foo\"\n match foo with {\n \"bar\" -> :nope\n \"baz\" -> :nope\n 12.34 -> :nope \n }\n "
:start 76
:type :number}
:type :number}
nil
{:data :nope
:token {:input :test
:lexeme ":nope"
:line 5
:literal :nope
:source " let foo = \"foo\"\n match foo with {\n \"bar\" -> :nope\n \"baz\" -> :nope\n 12.34 -> :nope \n }\n "
:start 85
:type :keyword}
:type :keyword}]]]
:match @match-fn
:token {:input :test
:lexeme "match"
:line 2
:literal :none
:source " let foo = \"foo\"\n match foo with {\n \"bar\" -> :nope\n \"baz\" -> :nope\n 12.34 -> :nope \n }\n "
:start 20
:type :match}
:type :match}
:value "foo"})
)
(deftest "string patterns work as expected"
(test (run `let "I {verb} the {noun}" = "I am the walrus"; (verb, noun)`) ["am" "walrus"])
(test (run `let "a {b} c {d}" = "a because I love you c yourself out the door"; (b, d)`)
["because I love you"
"yourself out the door"])
)
(deftest "lambdas may be defined and called"
(test (run `
let foo = fn () -> :foo
foo ()
`)
:foo)
(test (run `
let pair = fn (x, y) -> (x, y)
pair (:foo, :bar)
`)
[:foo :bar])
(test-error (run `
let foo = fn () -> :foo
foo (:bar)
`)
{:called @{:^type :fn
:body [[{:data @[]
:token {:input :test
:lexeme "("
:line 1
:source " let foo = fn () -> :foo\n foo (:bar)\n "
:start 15
:type :lparen}
:type :tuple}
nil
{:data :foo
:token {:input :test
:lexeme ":foo"
:line 1
:literal :foo
:source " let foo = fn () -> :foo\n foo (:bar)\n "
:start 21
:type :keyword}
:type :keyword}]]
:ctx @{}
:match @match-fn}
:msg "no match: function call"
:node {:data "foo"
:token {:input :test
:lexeme "foo"
:line 2
:literal :none
:source " let foo = fn () -> :foo\n foo (:bar)\n "
:start 28
:type :word}
:type :word}
:value [:bar]})
)

34
test/prelude.test.janet
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@ -1,34 +0,0 @@
# testing the prelude
(try (os/cd "janet") ([_] nil))
(import /scanner :as s)
(import /parser :as p)
(import /validate :as v)
(import /interpreter :as i)
(import /errors :as e)
(import /base :as b)
(import /load-prelude :as pre)
(use judge)
(defn run [source]
(when (= :error pre/pkg) (error "could not load prelude"))
(def ctx @{:^parent pre/ctx})
(def scanned (s/scan source :test))
(when (any? (scanned :errors))
(e/scan-error (scanned :errors)) (error "scanning errors"))
(def parsed (p/parse scanned))
(when (any? (parsed :errors))
(e/parse-error (parsed :errors)) (error "parsing errors"))
(def valid (v/valid parsed ctx))
(when (any? (valid :errors)) (each err (valid :errors)
(e/validation-error err)) (error "validation errors"))
(i/interpret (parsed :ast) ctx))
(deftest "debug add_msg"
(test (run `
let msgs = [1, :foo, nil]
let msg = do msgs > map (string, _)
msg
`)
@["1" ":foo" ":^nil"])
# (test (run `print! ("foo", "bar")`) :ok)
)

5
test/watchy.fish
View File

@ -1,5 +0,0 @@
#!/opt/homebrew/bin/fish
set FILE $argv[1]
fd $FILE | entr ./judgy.fish /_

81
turtle-graphics.md
View File

@ -1,81 +0,0 @@
# Turtle Graphics protocol
name: "turtle-graphics"
version: 0.1.0
### Description
Turtle graphics describe the movements and drawing behaviours of screen, robot, and print "turtles."
* `proto`: `["turtle-graphics", "{version number}"]`
* `data`: an array of arrays; each array represents a turtle command; the first element of a command array is the verb; any subsequent items are the arguments to the verbs.
* Valid arguments are numbers, strings, and booleans.
* Depending on what we end up doing, we may add arrays of these, representing tuples or lists, and/or objects with string keys whose text are well-formed keywords in Ludus. For now, however, arguments must be atomic values.
* E.g., `["forward", 100]`
* Each turtle has its own stream.
* At current, this protocol describes the behaviour of turtle-like objects, all of which "live" in the same "world"; there is not yet a provision for multiple canvases/worlds. That said, an additional field for "world" in at the top level may well be added in the future to allow for multiple worlds to unfold at the same time.
### Verbs and arguments
* `forward`, steps: number
- Moves the turtle forward by the number of steps/pixels.
* `back`, steps: number
- Moves the turtle backwards by the number of steps/pixels.
* `right`, turns: number
- Turns the turtle right by the number of turns. (1 turn = 360 degrees.)
* `left`, turns: number
- Turns the turtle to the left by the number of turns. (1 turn = 360 degrees.)
* `penup`, no arguments
- "Lifts" the turtle's pen, keeping it from drawing.
* `pendown`, no arguments
- "Lowers" the turtle's pen, starting it drawing a path.
* `pencolor`, red: number, green: number, blue: number, alpha: number, OR: color: string
- Sets the turtle's pen's color to the specified RGBA color.
* `penwidth`, width: number
- Sets the width of the turtle's pen, in pixels (or some other metric).
* `home`, no arguments
- Sends the turtle back to its starting point, with a heading of 0.
* `goto`, x: number, y: number
- Sends the turtle to the specified Cartesian coordinates, where the origin is the turtle's starting position.
* `setheading`, heading: number
- Sets the turtle's heading. 0 is the turtle's starting heading, with increasing numbers turning to the right.
* `show`, no arguments
- Shows the turtle.
* `hide`, no arguments
- Hides the turtle.
* `loadstate`, x: number, y: number, heading: number, pendown: boolean, width: number, color: string OR r: number, g: number, b: number, a: number
- Loads a turtle state.
* `clear`, no arguments
- Erases any paths drawn and sets the background color to the default.
* `background`, red: number, green: number, blue: number, alpha: number
- Sets the background color to the specified RGBA color, OR: color: string
These last two feel a little weird to me, since the background color is more the property of the **world** the turtle is in, not the turtle itself. Worlds with multiple turtles will be set up so that _any_ turtle will be able to change the background, and erase all paths.
That said, since we don't yet have a world abstraction/entity, then there's no other place to put them. This will likely be shifted around in later versions of the protocol.
### Other considerations
**Not all turtles will know how to do all these things.**
The idea is that this single abstraction will talk to all the turtle-like things we eventually use.
That means that some turtles won't be able to do all the things; that's fine!
They just won't do things they can't do; but warnings should go to `stderr`.
**Errors are not passed back to Ludus.**
These are fire-off commands.
Errors should be _reported_ to `stderr` or equivalent.
But Ludus sending things to its output streams should only cause Ludus panics when there's an issue in Ludus.
**Colors aren't always RGBA.**
For pen-and-paper turtles, we don't have RGBA colors.
Colors should also be specifiable with strings corresponding to CSS basic colors: black, silver, gray, white, maroon, red, purple, fuchsia, green, lime, olive, yellow, navy, blue, teal, and aqua.
**Turtles should communicate states.**
Ludus should have access to turtle states.
This is important for push/pop situations that we use for L-systems.
There are two ways to do this: Ludus does its own bookkeeping for turtle states, or it has a way to get the state from a turtle.
The latter has the value of being instantaneous, and gives us an _expected_ state of the turtle after the commands are all processed.
In particular, this will be necessary for the recursive L-systems that require pushing and popping turtle state.
The latter has the drawback of potentially allowing the turtle state and expected turtle state to fall out of synch.
The former has the value of always giving us the correct, actual state of the turtle.
It has the drawback of requiring such state reporting to be asynchronous, and perhaps wildly asynchronous, as things like moving robots and plotters will take quite some time to actually draw what Ludus tells it to.
(Being able to wait until `eq? (expected, actual)` to do anything else may well be extremely useful.)
That suggests, then, that both forms of turtle state are desirable and necessary.
Thus: turtles should communicate states (and thus there ought to be a protocol for communicating state back to Ludus) and Ludus should always do the bookkeeping of calculating the expected state.