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GHType Inference

Alexey
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Currently, Generic Haskell requires explicit specification of generic functions. This page documents the ongoing effort to add type inference to the Generic Haskell compiler.

---++Prototype

This is an implementation  prototype for the algorithm 
described in [[Type Inference for Generic Haskell]].

The prototype has been tested with GHC 6.4 .

---+++Obtaining and building

To obtain the prototype you need to invoke [[http://darcs.net][darcs]] as follows:
<verbatim>
darcs get http://www.cs.uu.nl/~alexey/repos/GH-type-infer/
</verbatim>

To compile the prototype you need to install the parser combinators distributed with the [[HUT.WebHome][Haskell Utrecht Tools]] library.

To build the prototype, simply type make:
<verbatim>
make
</verbatim>

---+++Running the prototype

You can take a look at the examples in the test directory.

Examples for generic equality:
<verbatim>
$ ./mygh -d 5 -i tests/Eq.ghs
(line 3, column 9)*4* (line 3, column 9) Generic scheme for eq is {|G_a|} G_a->G_a->Bool)
(line 16, column 4)Type :  => (List Int)->Bool
</verbatim>

Example for reduce function:
<verbatim>
$ ./mygh -d 5 -i tests/reduce2.ghs
(line 1, column 9)*4* (line 1, column 9) Generic scheme for reduce is
                                         {|G_a|} forAll a69.a69->G_a->a69)
(line 12, column 4)Type :  => M_a70->Bool->M_a70
</verbatim>

In the two examples above, we ran the frontend with a debug level
option of 5 (-d 5). That is the level for printing the types of all
the program bindings.

Additionally, you will notice a construct in the programs used for type inspection.

*Note*: The prototype currently lacks the simplifier function. As a consequence some corner cases are not typeable. A new version is in preparation.

---++Technical report

The technical report may be downloaded from [[Type Inference for Generic Haskell]].


-- Main.AlexeyRodriguez - 14 Oct 2005