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TypeIlluminator is a prototype tool for algorithmic debugging of type errors in Hindley-Milner-typed functional programs. TypeIlluminator constructs the typing tree, an algorithmic debugging tree, for programs written in a simple, Haskell-like language and enables free navigation through the tree in various ways and algorithmic debugging.

Compile or load it into a Haskell interpreter and evaluate main. The current textual user interface is rather simple. You first have to choose an example program and then choose between free navigation and algorithmic debugging. Both have many variants, the command ? gives an overview of the available commands. All examples are hard-coded in abstract syntax at the end of the source code. It should not be too difficult to add further examples. If you have interesting examples, please send them to me, just like any comments you have.

TypeIlluminator currently handles class contexts, but it does not yet help understanding them.

Note that the source contains code of Mark Jones' Typing Haskell in Haskell.

Olaf Chitil; Last Update: 2 March 2013