Algebraic data types for C99

Java 8 annotation processor and framework for deriving algebraic data types constructors, pattern-matching, folds, optics and typeclasses.

Monad, Functional Programming features for Golang

Fast and memory-efficient immutable collections and helper data structures

Algebraic data types for Python (experimental, not actively maintained)

An implementation of sum types in Julia

nextgen MLStyle: Generic Algebraic Data Type + Pattern Match

Recursive Variant: A simple library for Recursive Variant Types

A type-safe and space-efficient sum type for C# (comparable to discriminated unions in C or C++)

ADT sum type in typescript

Easy-to-use sum types in Julia

Expressive High-Performance Eager Functional Programming Library for C++ 11

Result, Either, Try, and Maybe monadic types for Java

Tagged unions for Elixir. Just that.

A code generator enabling sum-types in Dart

Wrap a Union for enhanced type-stability

Functional Enum type / Sum type for javascript with simple pattern matching

Track periodic goals — a sample iPhone app

Elm Either

A namedtuple-style library for defining immutable sum types in Python.