ludus/README.md

Ludus: A friendly, dynamic, functional language

A reference implementation of an interpreter for the Ludus programming language, using Clojure as a host language.

Ludus is part of the Thinking with Computers project, 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.

Status

Pre-alpha, still under active development. See the ludus-spec repo for progress notes and additional documentation.

Use

• Clone this repo.
  • git clone https://github.com/thinking-with-computers/ludus
• Have Clojure and Leiningen installed.
  • On a Mac: brew install clojure leiningen
• lein run {script}, it runs your script.
• Alternately, soon you'll be able to download a binary on the releases page.

Main features

• Pattern matching
• No operators: everything is called as a function
• Persistent or immutable data structures

Under construction

• Actor model style concurrency
• Strong nominal data typing, including tagged unions
  • Exhaustiveness-checking in match expressions in dynamically-typed code

Hello, world!

Ludus is a scripting language. At current it does not have a REPL (our aim is to get interactive coding absolutely correct).

Either

"Hello, world!"

=> "Hello, world!"

Ludus scripts (and blocks) simply return their last expression; this script returns the bare string (to stdout) and exits.

Or:

print ("Hello, world!")

=> Hello, world! 
=> :ok

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.

Some code

Fibonacci numbers:

& fibonacci!, with multi-clause fns/pattern matching

fn fib {
	(1) -> 1
	(2) -> 1
	(n) -> add (
		fib (sub (n, 1))
		fib (sub (n, 2)))
}

fib (10) &=> 55

More on Ludus

Most of the (very active, somewhat messy) thinking about Ludus is housed in the ludus-spec repository.