MuniHac 2024 - Fr, Oct. 11 - H. Siebenhandl: Exploring Haskell Language Server via the Cabal Plugin

H. Siebenhandl explores the integration of the cabal-plugin into the Haskell Language Server architecture and the Language Server Protocol.

The .cabal file defines what encompasses a package in the Haskell ecosystem. It is strictly required if you want to upload your package to Hackage. As such, almost anyone has to write or modify .cabal files at some point in their Haskell career, but due to its unique syntax, this often proves harder than necessary. Recently, Haskell Language Server started to close the gap between support for Haskell and cabal source files, by introducing the cabal-plugin. In this talk, we are going to take a closer look at the integration of the cabal-plugin into the architecture of the Haskell Language Server and explore its key concepts for providing a snappy, interactive developer experience. We are going to discuss the Language Server Protocol, and the plugin architecture, which allows us to extend HLS with a minimal amount of effort. These features will be explained by doing a deep-dive into the "cabal-plugin", which allows HLS to check .cabal files for syntax errors, provide completions, and even more features that help to read, write and modify .cabal files.