Coalton is an efficient, statically typed functional programming language that supercharges Common Lisp.
Coalton can be written in files:
(in-package #:coalton-user)
(coalton-toplevel
(define-type Symbol
(Symbol String))
(define (symbol-name sym)
(match sym
((Symbol s) s)))
(define-instance (Eq Symbol)
(define (== a b)
(== (symbol-name a) (symbol-name b)))
(define (/= a b)
(not (== a b))))
(define-type Expr
"A symbolic expression of basic arithmetic."
(EConst Integer)
(EVar Symbol)
(E+ Expr Expr)
(E* Expr Expr))
(declare diff (Symbol -> Expr -> Expr))
(define (diff x f)
"Compute the derivative of F with respect to X."
(match f
((EConst _) ; c' = 0
(EConst 0))
((EVar s) ; x' = 1
(if (== s x) (EConst 1) (EConst 0)))
((E+ a b) ; (a+b)' = a' + b'
(E+ (diff x a) (diff x b)))
((E* a b) ; (ab)' = a'b + ab'
(E+ (E* (diff x a) b)
(E* a (diff x b))))))
(declare dt (Expr -> Expr))
(define dt
"The time derivative operator."
(diff (Symbol "t"))))And at the REPL:
CL-USER> (in-package #:coalton-user)
COALTON-USER> (coalton (dt (E+ (EVar (Symbol "t"))
(EConst 1))))
#.(E+ #.(ECONST 1) #.(ECONST 0))Coalton has not reached "1.0" yet. This means that, from time to time, you may have a substandard user experience. While we try to be ANSI-conforming, Coalton may only work on SBCL 2.1.x.
This repository contains the source code to the Coalton compiler, and the standard library.
It also contains a few example programs, such as:
- Some simple pedagogical programs,
- A JSON parser piggybacking on a native Common Lisp library.
- An implementation of Jones's Typing Haskell in Haskell, and
- An implementation of a simple Quil parser.
Lastly and importantly, we maintain a collection of documentation about Coalton in the docs directory, including a standard library reference guide.
Install: Clone this repository into a place your Lisp can see (e.g., ~/quicklisp/local-projects/). (Coalton is not yet on Quicklisp.)
Use: Either run (ql:quickload :coalton), or add #:coalton to your ASD's :depends-on list.
Test: Run (ql:quickload :coalton/tests) to download the dependencies, then run (asdf:test-system :coalton).
Learn: We recommend starting with the Intro to Coalton document, and then taking a peek in the examples directory. It may also be helpful to check out the introductory blog post.
Want to ask a question about Coalton, propose a feature, or share a cool program you wrote? Try posting in the GitHub Discussions page!
We welcome contributions of all forms, especially as we stabilize toward a 1.0 release. We would be grateful to receive:
- bug reports (filed as issues),
- bug fixes and typo corrections (filed as pull requests),
- small example programs, and
- user experience troubles.