GSoC 2025 Ideas

This is a list of ideas for contributors who are considering to apply to Google Summer of Code 2025 for Haskell.org

For project maintainers

Are you working on a Haskell project and you could use the help of a contributor during the summer? Consider adding it as an idea here! You can contribute ideas by sending a pull request to our github repository (example from 2024). If you just want to discuss a possible idea, please contact us.

What is a good idea? Anything that improves the Haskell ecosystem is valid. The GSoC rules state that it must involve writing code primarily (as opposed to docs).

Projects should be concrete and small enough in scope such that they can be finished by the contributor. Past experience has shown that keeping projects “small” is almost always a good idea.

Important changes since 2021/2022: In the past, GSoC projects were expected to take up the equivalent of full time employment for a student. In 2021, this was reduced to half time positions: students were expected to work around 175 hours in a 10 week period. Since 2022, contributors now have the choice between a larger (around 350 hours) or a smaller project. Ideas should indicate in which category they fall.

Projects should benefit as many people as possible – e.g. an improvement to GHC will benefit more people than an update to a specific library or tool, but both are acceptable. New libraries and applications written in Haskell, rather than improvements to existing ones, are also welcome.

For students/contributors

We have added some tips on writing a proposal here. Please be aware that:

• This is not an all-inclusive list, so you can apply for projects not in this list and we will try our best to match you with a mentor.
• You can apply for up to two ideas (but only one can be accepted).

Table of Contents

1. CodeWorld GHC Update

CodeWorld GHC Update🔗

CodeWorld is a web-based educational environment for learning computer science using Haskell. It is based on GHCJS, an old project to compile Haskell to JavaScript with a modified GHC compiler.

GHCJS is no longer a good choice, as it is difficult to keep up to date with the latest GHC versions. However, modern versions of GHC have built-in backends for both JavaScript and WebAssembly, which are more reliable and easier to maintain, and kept up to date as part of the main line of GHC development. This project would involve updating CodeWorld to use one of the new GHC backends for JavaScript or WebAssembly.

This would involve updating the build system, and making any necessary changes to the CodeWorld runtime to work with the new backends.

The scope of the project can be adjusted based on the desired time frame and experience of the mentee. Some questions include:

• Is the goal to get a proof of concept, or a deployable replacement?
• Will the rule-based requirements checker also be updated to newer GHC versions?
  • This requires updating the GHC API usage.
  • This feature is, to my knowledge, not currently used by anyone.
• Will the educational dialect be updated?
  • If so, how do we handle unconstrained universal equality? Note that this likely requires development of a non-trivial GHC plugin.
  • If not, how do we deploy both versions simultaneously (if a deployable replacement is the goal)?
• What additional improvements are enabled by newer GHC versions and the new backends?

Mentorship

• Chris Smith (cdsmith)
• Ideally, a second mentor with experience in one or both of GHC JS/WASM backends

Difficulty and size

The difficulty of this project is medium, as there are significant infrastructure and build system challenges to address. Depending on choices made, this may become hard.

The minimum size of this project is 175 hours, but there is likely more work depending on the mentee’s desired scope and ideas.