Open-source alternatives to OneOf

Odin is a compiled, statically typed systems programming language designed for high-performance software development. It focuses on pragmatic low-level memory control, providing a toolset for manual memory management and precise control over hardware utilization. The language is distinguished by its flexible memory model, which includes custom allocators and precise data layout capabilities to optimize resource usage. It features a comprehensive foreign function interface for importing assembly files and linking with external libraries using configurable calling conventions. The type system

This project is a collection of technical reference guides and cheatsheets for implementing static typing patterns with TypeScript in React. It serves as a comprehensive typing guide for applying static types to components, hooks, and state management. The resource provides specific patterns for defining component properties, reference handles, and generic types. It includes detailed signatures for handling synthetic events, form submissions, and the creation of typed custom hooks using tuple assertions. The documentation covers a broad range of capability areas, including state management v

The Concise TypeScript Book: A Concise Guide to Effective Development in TypeScript. Free and Open Source.

This is a comprehensive tutorial for learning TypeScript, designed for JavaScript programmers who want to understand the language's type system and modern features. The resource covers TypeScript's core identity, including its structural type compatibility, compile-time type erasure, declaration file merging, and the discriminated union pattern for precise type narrowing. The tutorial distinguishes itself by providing a progressive learning path from basic JavaScript concepts to advanced TypeScript patterns. It covers generic type parameter constraints, tuple types with fixed-length positions

This project is a Scala programming course and educational resource. It provides a set of lessons covering the core fundamentals of the language, ranging from basic syntax to advanced type systems. The material includes a functional programming tutorial focused on higher-order functions and pattern matching, as well as guides on managing asynchronous execution and concurrency. It also serves as a resource for understanding the Java Virtual Machine and language interoperability. The course covers the application of polymorphism and variance for type-safe data structures and the use of specifi

Entitas is a data-oriented Entity Component System framework for Unity. It is designed to separate game state into components and logic into systems, utilizing a data-oriented design to optimize CPU cache usage, memory usage, and processing speed. The framework includes a C# source code generator that automatically produces boilerplate classes, entity accessors, and context singletons to reduce manual coding. It also provides a Unity editor debugging tool for real-time runtime state visualization, system performance monitoring, and visual entity inspection. The system manages entity lifecycl

Roc is a statically typed, functional programming language built around immutable-by-default semantics, exhaustive pattern matching on tag unions, and a type system that combines optional explicit annotations with full compile-time type inference. Its core identity centers on correctness and expressiveness, using tagged unions for error handling with a question-mark operator for early error propagation, and a trailing-bang naming convention that makes side-effect boundaries syntactically visible at every call site. The language distinguishes itself through a platform-based I/O abstraction tha

Mapperly is a C# source generator used for high-performance object-to-object mapping in .NET. It functions as a compile-time mapping library that produces the necessary transformation code during the build process, eliminating the need for runtime reflection when converting between domain models and data transfer objects. The tool distinguishes itself by providing type-safe diagnostic validation and strict mapping enforcement, emitting warnings for unmapped properties at compile time. It includes specialized capabilities for circular reference handling and deep cloning to maintain object iden

Returns is a functional programming library for Python that provides type-safe containers for managing state, error handling, and optionality. It serves as a monadic container library and a type-safe error handling framework, replacing traditional try-catch blocks and null checks with Result and Optional containers to treat exceptions as data. The project is distinguished by its use of a specialized Mypy static analysis plugin to validate functional pipelines and emulate higher kinded types. It provides mechanisms for isolating side effects through IO containers and offers a framework for typ

Dhall is a type-safe configuration language designed to create programmable configuration files that are guaranteed to terminate. It is a non-Turing-complete language that uses a strict type system to ensure correctness and prevent infinite loops during evaluation. The project functions as a deterministic configuration engine and marshalling tool, converting programmable expressions into static formats such as JSON, YAML, and Bash. It distinguishes itself through a focus on security and integrity, using semantic hashing to pin remote imports and enforcing origin policies to prevent data exfil

Arrow is a functional programming library for Kotlin that provides tools for implementing data-oriented programming patterns. It serves as a framework for typed error handling, a concurrency toolkit, and a library for the manipulation of immutable data. The project distinguishes itself through specialized capabilities for managing application failures using explicit types instead of exceptions and implementing resilience patterns such as circuit breakers and retry policies for distributed services. It also provides optics to update and query deeply nested immutable data structures without man

Valibot is a modular, type-safe schema library for validating and parsing structural data in TypeScript environments.

This library provides a comprehensive collection of fundamental computer science primitives implemented in Go. It serves as a resource for both educational purposes and production applications, offering standard tools for organizing, searching, and sorting data. The implementation leverages language-level type parameters to ensure type safety while maintaining flexibility across different data types. It utilizes interface-driven polymorphism and pointer-based memory management to define common behaviors and handle complex structures. To optimize performance, the library employs in-place data

Participle is a Go parser generator and toolkit for building language frontends. It provides a declarative grammar framework that uses reflection and struct tags to map input patterns directly into typed data structures. The library features a stateful lexical analyzer that employs state machines to handle nested or modal patterns. It includes a lexer code generator to produce optimized code, reducing runtime memory allocations and increasing throughput. The project covers recursive descent parsing with support for union types via sealed interfaces and custom parsing logic through interface-

CSharpFunctionalExtensions is a functional programming library for C# that provides a framework of monadic containers, pipeline orchestration tools, and immutable domain object patterns. It implements the result pattern to handle operation success and failure as values, reducing the reliance on exceptions for control flow. The library enables railway-oriented programming by chaining multiple operations into sequences that execute only upon the success of previous steps. It provides specialized wrappers for optional and result types to minimize null checks and nested conditional logic, alongsi

This repository serves as an educational resource and tutorial collection focused on the principles and implementation of functional programming. It provides a structured guide for developers to learn how to apply functional paradigms to improve software architecture, logic design, and code maintainability. The project distinguishes itself by demonstrating how to implement functional concepts across both statically and dynamically typed programming languages. By utilizing examples in Haskell, OCaml, and Python, it illustrates the practical application of techniques such as immutability, highe

This project provides a set of software architecture guidelines, Lisp coding standards, and functional programming patterns for Clojure development. It establishes best practices for implementing declarative logic and managing shared state through the use of persistent data structures and atomic references. The guide covers standards for documenting public APIs and organizing project directories to ensure portable library distribution. It details the application of consistent formatting and naming rules to improve source code readability and team collaboration. The scope extends to idiomatic

LearnPython is a programming tutorial consisting of a collection of practical code examples used to demonstrate Python language features and programming patterns. It serves as a comprehensive learning resource that implements core language concepts through functional code. The project provides specialized guides and samples covering several key domains. These include asynchronous network programming with event loops and coroutines, data visualization using numerical datasets for 2D and 3D plots, and web scraping for fetching content and automating login flows. It also features instructions on

Pytype is a static code analysis tool and type inference engine for Python. It functions as a static type analyzer that detects type mismatches and verifies type annotations without requiring full manual hinting, while also serving as a type stub generator for producing standalone definition files. The project distinguishes itself by automatically determining variable and function types through an analysis of code patterns and assignments. This inference engine allows for structural code verification and the generation of type stubs that describe the interfaces of modules and functions. The

This project is a comprehensive educational suite of coding challenges and implementation guides focused on JavaScript. It provides a collection of programmatic exercises and interview questions designed to practice core logic and algorithms. The repository serves as a test-driven development workbook, pairing coding problems with test suites to verify the correctness of implemented solutions. It includes a specific framework for exercise solution verification and the integration of asynchronous logic into automated testing flows. The content covers a wide range of computer science building

Scalaz is a functional programming library for Scala that provides a collection of purely functional data structures and type classes. It functions as a framework for organizing functional behaviors into hierarchies to enable generic programming and type-safe transformations. The library includes tools for composing and managing nested functional effects within a single type stack through a monad transformer system. It provides data structures for representing and combining input, output, and optionality effects. The project covers a broad surface of functional abstractions, including the im

This project is a comprehensive performance programming guide and reference for the Go language, focusing on runtime efficiency and memory optimization. It provides a collection of patterns and techniques designed to increase execution speed by reducing garbage collection overhead and optimizing memory usage. The resource distinguishes itself through detailed reference implementations for memory optimization, such as escape analysis, object pooling, and structure memory alignment. It offers specific strategies for reducing binary size and improving CPU cache efficiency through structure memor

Amber is a transpiler that translates high-level source code into executable shell scripts for Bash, Zsh, and Ksh. It provides a type-safe environment for shell script generation, allowing for static type validation and the creation of standalone executable scripts. The project distinguishes itself through a compilation process that includes tree-shaking import optimization to reduce output size and template-based script wrapping for custom headers and footers. It utilizes a module-based dependency resolution system with visibility controls to manage code reuse across multiple files. The lan

This is a C++ ranges library and extension to the Standard Template Library that provides a collection of composable algorithms and lazy views for processing data sequences. It functions as a lazy sequence processing framework and a template meta-programming library for manipulating type lists and performing compile-time type computations. The project enables functional programming patterns in C++ through the use of pipe syntax and partial application to create readable, left-to-right data transformation chains. It allows for the construction of lazy data pipelines that filter and transform e

This project is a collection of curated guidelines and manuals for writing clean, idiomatic, and maintainable code in Scala. It serves as a comprehensive guide for Scala coding standards, functional programming design, and enterprise software architecture. The repository provides specific strategies for concurrency management, including patterns for actors, futures, and thread pools to ensure thread safety. It also contains a performance optimization manual focused on reducing memory allocations and managing garbage collection pressure to improve runtime efficiency. The guides cover a broad

Frege is a purely functional programming language that compiles to JVM bytecode, providing Haskell-like semantics for the Java platform. It is built around a Haskell-inspired compiler that implements non-strict evaluation and a static type inference system to ensure data immutability and prevent side effects. The project distinguishes itself through a sophisticated type system featuring rank polymorphism, type-class based dispatch, and static purity enforcement. It includes a JVM language bridge and a foreign function interface that map Java classes and interfaces into functional types, allow

This project is a C# algorithms library and collection of data structures. It serves as a computer science reference providing practical implementations of classic sorting, searching, and graph traversal patterns. The library includes a dedicated string processing toolkit for analyzing text similarity, computing edit distances, and managing prefix-based searches. It also features a graph theory implementation for modeling network relationships and calculating shortest paths. The codebase covers a broad range of capabilities, including the management of linear and hierarchical collections, tr