Haskell Errors

So you would like to help improve the error messages we see in the Haskell toolchain and ecosystem?

Welcome! We're glad to have you, and we will do our best to ensure your efforts are worthwhile.

Project Goals

• Serve the Haskell community, focusing on improvements to the error messages seen in the Haskell ecosystem.

• Lower Haskell's barrier-to-entry by increasing the general understanding of the error messages experienced during development.

What and How?

This project is taking shape, so many details are still being worked out, however:

• Using the issue tracker, this repo will provide a space and workflow for the discussion and collaboration around improving error messages.
• We are interested in building a catalog of error messages for each tool in common use (GHC, Cabal, Stack, ghcup, HLS, etc).
• For each error message that is identified for potential improvement:
  • We would like to have a reasonable means of reproducing the error message under different circumstances
  • We should identify specific improvements to the messaging
  • We will reach out to and work collaboratively with tool developers
  • We should document and help improve understanding of the error messaging
• For tools that use error message codes:
  • We describe the messages and how to interpret them in the Haskell Message Index (see below)

As a result, this repo may include code that demonstrates the errors we wish to improve, as well as code and material to render documentation relevant to explaining each error and the possible situations the error relates to.

Contributor Expectations

We welcome contributions that help to further progress the project towards its goals.

Contributions may come in the form of changes to the code base, as well as opening or commenting on issues and pull requests.

All contributors are expected to follow the Haskell Foundation's Code of Conduct.

The Haskell Message Index

Haskell tooling emits a variety of errors, warnings, and other messages. In an unreleased branch, GHC emits a unique code for each message that allows it to be identified. This site allows these codes to be looked up, providing examples, context, and further information that can make them easier to understand.

Please see CONTRIBUTING.md for instructions on improving the site. Thanks!

Running Locally

The site is built with the Hakyll static site generator. To view the site locally, run:

$ cabal run -- site watch

or

$ stack run -- site watch

which fires up an HTTP server on localhost:8080.

Maintenance

The Message Index is a project of the Haskell Foundation. Please get in touch if you have ideas, requests, or any other feedback!