Official Haskell IDE support via the language server protocol (LSP)
Haskell Language Server is an official IDE support tool for Haskell that implements the language server protocol (LSP), enabling integration with code editors. Built on top of the ghcide library, which provides core IDE functionality, it offers a comprehensive set of plugins that extend its capabilities—including tools for code evaluation, type signature changes, class method generation, record field manipulation, HLint integration, and various code refactoring operations. The project is written in Haskell and works with GHC and build tools like Cabal and Stack, with benchmarking infrastructure built using Shake and supplemented by a custom in-memory build graph system called hls-graph.