[Haskell-cafe] workarounds for Codec.Compression.Zlib errors in darcs

Duncan Coutts duncan.coutts at worc.ox.ac.uk
Thu Nov 27 04:28:24 EST 2008

On Wed, 2008-11-26 at 23:16 +0000, Malcolm Wallace wrote:
> > ... to work out the C types and then map them to Haskell ones, to
> > check they're the same as the declared types in the .hs files.
> I'd like to point out that the FFI specification already has such a  
> mechanism.
> That is, if you use the optional specification of a header file for  
> each foreign import, and if your Haskell compiler can compile via C,  
> then any checking that types match between Haskell and C can be  
> performed automatically, by the backend C compiler.

Yes, it would have caught a similar problem in an argument position, but
not in the result.

> [ OK, so that is not the whole story, and there are good reasons why  
> it might not always work out, but I still think it was an important  
> principle in the original FFI design. ]

And covering those holes requires a tool that can grok C.


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