Lexically scoped type variables

Christian Maeder maeder at tzi.de
Thu Feb 2 12:19:02 EST 2006

> | Simon Peyton-Jones wrote:
> | > I'm very interested to know whether you like it or hate it.
> | > In the latter case, I'd also like to know whether you also
> | > have programs that will be broken by the change.
> | 
> | I don't use GADTs yet and I assume this change will not (seriously)
> | break our code, but let me/us know which compiler we should use for
> testing.

I've installed now ghc-6.5.20060201 and I get quite a few errors of the 

     A pattern type signature cannot bind scoped type variables `s'
       unless the pattern has a rigid type context

(and these are not always easy to fix in unknown non-haskell98 code by 
adding a "forall" and/or omitting the pattern type signatures)


You may try to translate the attached sources by:

   ghc --make -cpp -fallow-undecidable-instances -fglasgow-exts 

(and tell me how I should fix this)
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