title: Haskell description: "Configure Haskell language support in Zed, including language servers, formatting, and debugging."

Haskell

Haskell support is available through the Haskell extension.

• Tree-sitter: tree-sitter-haskell
• Language Server: haskell-language-server

Installing HLS

Recommended method to install haskell-language-server (HLS) is via ghcup (curl --proto '=https' --tlsv1.2 -sSf https://get-ghcup.haskell.org | sh ):

ghcup install hls
which haskell-language-server-wrapper

Configuring HLS

If you need to configure haskell-language-server (hls) you can add configuration options to your Zed settings.json:

{
  "lsp": {
    "hls": {
      "initialization_options": {
        "haskell": {
          "formattingProvider": "fourmolu"
        }
      }
    }
  }
}

See the official configuring haskell-language-server docs for more options.

If you would like to use a specific hls binary, or perhaps use static-ls as a drop-in replacement instead, you can specify the binary path and arguments:

{
  "lsp": {
    "hls": {
      "binary": {
        "path": "static-ls",
        "arguments": ["--experimentalFeatures"]
      }
    }
  }
}