fir-lang/fir

---

fir-lang/fir.json

{
  "createdAt": "2024-06-18T19:15:57Z",
  "defaultBranch": "main",
  "description": "Fir programming language",
  "fullName": "fir-lang/fir",
  "homepage": "https://fir-lang.github.io/",
  "language": "Rust",
  "name": "fir",
  "pushedAt": "2025-11-24T20:04:21Z",
  "stargazersCount": 81,
  "topics": [
    "programming-language"
  ],
  "updatedAt": "2025-11-24T20:02:37Z",
  "url": "https://github.com/fir-lang/fir"
}

Fir programming language

Fir is a programming language with:

• Static types and indentation sensitive syntax
• Traits (typeclasses) for polymorphism
• Monomorphisation and unboxed/value types
• [Effects][effects]
• [Built-in tooling][tooling] and a [large standard library][libs]

For introduction, see blog posts:

• [Error handling in Fir][1]
• [Throwing iterators in Fir][2]
• [Fir is getting useful][3]

Implementation notes:

• [How Fir formats comments][4]

[1] !: https://osa1.net/posts/2025-01-18-fir-error-handling.html [2] !: https://osa1.net/posts/2025-04-17-throwing-iterators-fir.html [3] !: https://osa1.net/posts/2025-09-04-fir-getting-useful.html [4] !: https://osa1.net/posts/2025-09-27-fir-formatter.html [tooling] !: https://github.com/fir-lang/fir/issues/28 [libs] !: https://github.com/fir-lang/fir/issues/76 [effects] !: https://osa1.net/posts/2025-06-28-why-effects.html