# louthy/language-ext

C# pure functional programming framework - come and get declarative!

Repository: https://github.com/louthy/language-ext
Canonical: https://ross.abutalabs.com/products/language-ext
Language: C#
License: MIT
License Family: permissive
Topics: c-sharp, functional-languages, monads, monad-transformers, immutable-collections, higher-kinded-types, language-ext, f-sharp, immutable-types, monad, bcl, ad-hoc-polymorphism, functional-programming, lenses, records, structural-equality, functor, applicative, semigroup, monoid
Last push: 2026-07-29T08:30:02+00:00

## Health v2 (maintenance only)
Score: 84/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 95, release rhythm 60, longevity 100
- inputs: {"age_days": 4308, "days_push": 35, "days_rel": 246, "gap_med": 4, "n_releases_24m": 34}
- flags: prerelease_only
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 7084, forks 450 (observed 2026-08-28T04:09:55.757248+00:00)

## What it is
A C# library that provides a pure functional programming framework, using and abusing C# language features to make code more declarative and robust. It offers monads, monad transformers, immutable collections, higher-kinded types, parser combinators, and functional effects for building maintainable codebases.

## Use cases
- write functional-style C# code with monads like Option and Either
- use immutable collections and persistent data structures in .NET
- build parser combinators in C# like Haskell's Parsec
- handle errors functionally instead of exceptions
- manage concurrency and shared state atomically
- use higher-kinded types and ad-hoc polymorphism in C#

## When to choose
- you want declarative, pure functional code in C#
- you need robust error handling without exceptions
- you want immutable data structures and structural equality
- you're building large C# codebases where reducing cognitive load matters

## When to avoid
- your team is unfamiliar with functional programming concepts
- you need minimal dependencies or tiny binary size
- you're working in a codebase heavily tied to imperative idioms

## Facets
- artifact type: library
- maturity: active
- function: parser, serialization, concurrency, error-handling
- domain: programming-languages, developer-tools
- platform: dotnet, cross-platform
- tags: functional-programming, monads, immutable-collections, higher-kinded-types, parser-combinators, csharp, algorithms

## Member repositories
- louthy/language-ext (main) score 84

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:09:55.757248+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 2026-08-29T17:40:11.429718+00:00, confidence not recorded.
  - readme: https://github.com/louthy/language-ext (fetched 2026-08-28T04:09:55.757248+00:00, sha c018963ea6df)
- Data as of 2026-08-30T08:39:29.467469+00:00.