cabal-explain is a utility tool inspired by rustc --explain. It brings similar functionality to Haskell, allowing you to display explanations for Haskell error messages directly from your terminal. This utility leverages the recently added plugin functionality in cabal-install, enabling its use as a cabal explain subcommand.

cabal-explain fetches explanations from the Haskell Foundation's error-message-index using curl and employs lowdown to display the content, formatted with ANSI color codes, in a user-friendly manner on your terminal.

Although this functionality can be replicated with the following shell alias:

alias cabal-explain='curl "https://raw.githubusercontent.com/haskellfoundation/error-message-index/main/message-index/messages/$1/index.md" | lowdown -tterm'

I am distributing cabal-explain as a Nix flake for your convenience :)

You can install cabal-explain by running the following command:

nix profile install "github:yvan-sraka/cabal-explain"

Using cabal-explain is straightforward. Once installed, simply use the cabal explain command followed by the error message code about which you need more information:

cabal explain <error-message-code>