Haskell

Haskell is a purely functional programming language based on lambda calculus, featuring referential transparency, immutability, and lazy evaluation. It addresses the challenge of building and maintaining reliable software by expressing domain rules, invariants, and possible states directly in code, helping catch mistakes before they reach production and keeping codebases maintainable as requirements and teams change.

The language is statically typed with type inference, purely functional, and supports concurrent, parallel, and streaming programming through GHC, which includes a parallel garbage collector and lightweight concurrency library. Tooling includes GHCup for installing the toolchain, cabal for building projects, and haskell-language-server for editor integration. The site also provides a playground for trying code in the browser, documentation, and a security advisory database covering known issues in Haskell libraries and open source tools, along with security guides for programmers and project maintainers.

Haskell is aimed at developers modeling complex domains and building production systems, with support across major platforms via GHC. The language and tooling are open source; no specific packaging, editions, or pricing details are indicated.