# coalton-lang/coalton

Coalton is an efficient, statically typed functional programming language that supercharges Common Lisp.

Repository: https://github.com/coalton-lang/coalton
Canonical: https://ross.abutalabs.com/products/coalton
Homepage: https://coalton-lang.github.io/
Language: Common Lisp
License: MIT
License Family: permissive
Topics: functional-programming, common-lisp, type-safety
Last push: 2026-08-15T18:36:41+00:00

## Health v2 (maintenance only)
Score: 93/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 97, release rhythm 84, longevity 100
- inputs: {"age_days": 1829, "days_push": 18, "days_rel": 111, "gap_med": 1.0, "n_releases_24m": 7}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1752, forks 111 (observed 2026-08-28T04:05:31.741363+00:00)

## What it is
Coalton is a statically typed functional programming language embedded in Common Lisp, drawing ideas from Haskell, Scheme, and OCaml. It compiles to efficient Common Lisp code and integrates directly into Lisp packages and the REPL with compile-time type checking.

## Use cases
- write statically typed functional code inside Common Lisp
- get compile-time type errors in a Lisp project
- use algebraic data types and pattern matching in Common Lisp
- build high-performance typed numerical or scientific code in Lisp
- gradually add type safety to an existing Common Lisp codebase

## When to choose
- you develop in Common Lisp and want Haskell-style static typing without leaving the ecosystem
- you need typed functional programming with Lisp's interactive REPL and debugging
- you want efficient compiled code with type safety for production Lisp applications

## When to avoid
- you want a standalone general-purpose language rather than a Lisp-embedded one
- your project is not Common Lisp based
- you need dynamic typing or full Common Lisp metaprogramming semantics

## Facets
- artifact type: library
- maturity: active
- function: programming-language, type-system, compiler
- domain: programming-languages
- platform: cross-platform, cli
- tags: common-lisp, statically-typed, haskell-inspired, embedded-language, type-inference, functional-programming

## Member repositories
- coalton-lang/coalton (main) score 93

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:05:31.741363+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T03:28:25.131778+00:00, confidence not recorded.
  - readme: https://github.com/coalton-lang/coalton (fetched 2026-08-28T04:05:31.741363+00:00, sha ec7cddde0c21)
  - homepage: https://coalton-lang.github.io/ (fetched 2026-08-29T11:06:18.562586+00:00, sha 5b0809ffa8bc)
- Data as of 2026-08-30T08:39:29.467469+00:00.