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abyss-rs

Rust implementation of Abyss programming language

Made in abyss

Getting started

  • Download or compile source code.
  • Run the program and enter repl automatically (default lazy mode).

REPL functions

  • quit: Quit repl
  • help: Get help
  • eager: Turn on eager mode (where strict evaluation is the default)
  • lazy: Turn on lazy mode (where lazy evaluation is the default)
  • debug: Turn on debug mode

Expressions

  • Function application: (f x)
  • Let bindings: (let ((x value) (y value) ...) expression)
  • Lambda abstraction: (lambda (x y z ...) expression)
  • If branches: (if expression true-branch false-branch)
  • Pattern matching: (case expression ((case1 value) (case2 value) ...))

Declarations

  • Definition: (define x expression) | (define (f x y ...) expression)
  • Data abstraction: (data x) | (data (cons x y ..))

Environment

  • Integers
  • Symbols
  • Strings
  • Real numbers
  • ::: List constructor
  • +-*/: Arithmetic operators

Features

  • Typed dynamic programming language
  • Highly configurable and scalable
  • Experimental for the next generation

Expressions

  • S-Expressions
  • Scalable front-end syntax with parser combinator

Evaluation

  • Optional evaluation strategy: eager or lazy
  • Flexible GC strategy

Data abstraction

  • Haskell-like data declaration
  • Pattern matching everywhere

Type system

  • Dependent type system

Examples

  • Factorial
(let (((fact n) (case n ((0 1) (n (* n (fact (- n 1)))))))) (fact 5))
;==> 120
  • Generating list
(let (((gen s n) (case n ((0 ()) (n (:: s (gen s (- n 1)))))))) (gen 'T_T 10))
; strict ==> (T_T T_T T_T T_T T_T T_T T_T T_T T_T T_T)
; lazy   ==> (:: T_T <thunk>)