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Project: CodeWorld
Description: Educational computer programming environment using Haskell
Maintainers/liaisons: Chris Smith

What It Is

CodeWorld is a web-based development system for Haskell programming in education. The web site provides a code editor, in-browser preview, and options to load and save programming projects. The library is inspired by Gloss, and provides a purely functional API for drawing pictures, animations, and interactive programs.

The main intent of CodeWorld is to be used for middle school aged children. Because of this, it defaults to a simplified variant of Haskell. However, a full Haskell version is available and widely used.

Possible Projects

CodeWorld is a large project, and has a lot going on!

If you're a beginner: consider using CodeWorld to build your own project! There are APIs that make it ease to create fractals and geometric patterns, animations, physics simulations, and casual games. In fact, I'm fairly comfortable saying that CodeWorld's collaboration API is the easiest way to build multi-player games in Haskell that you'll find!

New contributions to the gallery are helpful (bug). So are contributions to the online guide!

If you want to jump in and work on more fundamental changes to CodeWorld, then here's a list of tasks of reasonable scope for a weekend.

  • Improving the editor with better autocomplete (bug, bug), links between declarations and usage (bug), collaborative coding using together.js (bug), or other editor features (bug, bug).
  • Exporting drawings and animations to image files, animated gifs, or video files. (bug)
  • Debugging features (bug, bug, bug)
  • Better support for console-mode programs. (bug)
  • Constructive area geometry (bug)
  • Improve multi-player game framework by improving the lobby UI and error handling (bug, bug), random player matching (bug), WebRTC (bug), desync detection (bug), or smoothing network latency (bug)

There are other possibilities, as well, if none of this catches your eye.


You do not need to install anything to use CodeWorld for your own project! Just visit [1] or [2] to get started. (The first link is the simplified educational language variant; the second is plain Haskell.) You can also make some changes to the front end by just editing JavaScript and opening files in the browser.

If you want to make most deeper changes, installation is done by cloning the repository, and then running, then, and finally Be aware that running will delete your ~/.ghc directory!

Installing takes some time (mostly building and installing node.js and GHCJS), but only needs to be done once. Future changes can just run the build and run scripts, which is considerably faster. I'll be happy to help with this process, either at BayHac or earlier.