# The Carth Programming Language

Purely functional programming with lisp-syntax. Less infix, more parens!

## 1 *WORK IN PROGRESS*

Just as a little disclaimer: this project is in the very early stages of development, so there are no guarantees of stability etc.

## 2 Why Carth?

- Scheme-inspired syntax and feel
- Static, Hindley-Milner typechecking à la ML
- Currying
- LLVM-based backend
- Native support for literate programming in Org-mode

## 3 Example

Just to give you a quick taste. More examples can be found in the
`examples`

directory in the repository.

;; Disclaimer: This doesn't quite work yet, but we're getting close! (define main fizzbuzz) (define (fizzbuzz _) (foldr (after seq (after display fizzbuzz')) unit (range 0 100))) (define (fizzbuzz' n) (match (Pair (% n 3) (% n 5)) [(Pair 0 0) "Fizzbuzz"] [(Pair 0 _) "Fizz"] [(Pair _ 0) "Buzz"] [_ (show-int n)])) (type (Pair a b) (Pair a b)) ;; We implement some routines in a helper library in a language with C FFI, like ;; Rust. (extern display (Fun String Unit)) (extern show-int (Fun Int String)) ;;? Function composition. Read "f after g". (define: (after f g x) (forall [a b c] (Fun (Fun b c) (Fun a b) (Fun a c))) (f (g x))) ;;? Sequence operations (define (seq _ b) b) ;;? Inclusive range (define: (range first last) (Fun Int Int (Iter Int)) (Iter (fun _ (if (> first last) None (Some (Pair first (range (succ first) last))))))) ;;? An iterator. Equivalent to a lazy linked list (type (Iter a) (Iter (Fun Unit (Maybe (Pair a (Iter a)))))) (type (Maybe a) None (Some a)) (define: (foldr f b as) (forall [a b] (Fun (Fun a b b) b (Iter a) b)) (match (next as) [None b] [(Some a as') (f a (foldr f b as'))])) (define: next (forall [a] (Fun (Iter a) (Maybe (Pair a (Iter a))))) (fun-match [(Iter f) (f unit)])) (define (succ n) (+ n 1))

## 4 Documentation

## 5 Development

All development on the Carth project happens openly on GitLab in
`JoJoZ/carth`

. The source for this website is also on GitLab in
`JoJoZ/carth-website`

.

## 6 License

Both the Carth project and this website itself are licensed under the AGPLv3.

Copyright (C) 2019 Johan Johansson

This program is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more details.

See LICENSE