69 lines
2.3 KiB
Markdown
69 lines
2.3 KiB
Markdown
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## Ludus: A friendly, dynamic, functional language
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A reference implementation of an interpreter for the Ludus programming language, using Clojure as a host language.
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Ludus is part of the [_Thinking with Computers_ project](https://thinking-with-computers.github.io), run by Scott Richmond at the University of Toronto. Ludus is our research language, which aspires to be a free translation of Logo for the 2020s.
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### Status
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Pre-alpha, still under active development. See [the ludus-spec repo for progress notes and additional documentation](https://github.com/thinking-with-computers/ludus-spec/blob/main/todo.md).
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### Use
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* Clone this repo.
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- `git clone https://github.com/thinking-with-computers/ludus`
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* Have Clojure and Leiningen installed.
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- On a Mac: `brew install clojure leiningen`
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* `lein run {script}`, it runs your script.
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* Alternately, soon you'll be able to download a binary on the [releases page](https://github.com/thinking-with-computers/ludus/releases).
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### Main features
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* Pattern matching
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* No operators: everything is called as a function
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* Persistent or immutable data structures
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#### Under construction
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* Actor model style concurrency
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* Strong nominal data typing, including tagged unions
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- Exhaustiveness-checking in `match` expressions in dynamically-typed code
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### `Hello, world!`
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Ludus is a scripting language. At current it does not have a REPL (our aim is to get interactive coding absolutely correct).
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Either
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```
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"Hello, world!"
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```
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`=> "Hello, world!"`
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Ludus scripts (and blocks) simply return their last expression; this script returns the bare string (to `stdout`) and exits.
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Or:
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```
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print ("Hello, world!")
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```
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```
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=> Hello, world!
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=> :ok
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```
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Or, you can use a the `print` function, which sends a string to `stdout`. 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.
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### Some code
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Fibonacci numbers:
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```
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& fibonacci!, with multi-clause fns/pattern matching
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fn fib {
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(1) -> 1
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(2) -> 1
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(n) -> add (
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fib (sub (n, 1))
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fib (sub (n, 2)))
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}
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fib (10) &=> 55
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```
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### More on Ludus
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Most of the (very active, somewhat messy) thinking about Ludus is housed in the [ludus-spec repository](https://github.com/thinking-with-computers/ludus-spec).
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