[Haskell-cafe] Who generates Haskell code and uses type information at runtime? (fwd)

[Chris Brown]

I'm not sure if you got my previous message, as I was having some 
problems posting to the list...

> Putting in a nutshell, I generalize an extensional defined function
> definition into a recursive one. This is done in a number of steps by
> modifying expressions and exploiting type information of
> sub-expressions. For example:
> 
> rev [] = []
> rev [a] = [a]
> rev [a,b] = [b,a]
> rev [a,b,c] = [c,b,a]
> 
> ~~>
> 
> rev x = y
> 
> ~~>
> 
> rev [] = []
> rev (x:xs) = (y:ys)
> 
> ~~>
> 
> rev [] = []
> rev (x:xs) = (last (x:xs)) : (reverse (x:xs))
> 
> 
> The initial set of rules is given by the user (in a file, via IO, ...).
> The problem later is to infer the type of an intermediate variable, e.g.
> 'y'.

I'm still not entirely sure what you want to do here. But it sounds like HaRe 
could already do most of this for you via a sequence of folds, unfolds, 
introduce pattern matching and generative folding. HaRe already has 
built-in support for some symbolic evaluation, which is already used in the generative
fold refactoring, and has type checking support too.

http://www.cs.kent.ac.uk/projects/refactor-fp/hare.html

If it doesn't do exactly what you want out of the tin, it does have a large API 
for designing transformations over Haskell code.

http://www.cs.kent.ac.uk/projects/refactor-fp/hare/haddock/RefacUtils.html



Chris.




> 
> Thanks,
> 
> Martin
> 
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Chris Brown

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