[Haskell-cafe] Re: Additonal types for Foreign.C.Types

[Ross Mellgren]

fatype is the function argument type. atype[i] are type arguments.  
qtycon is a qualified (e.g. possibly with module prefix) type  
constructor, e.g. Just

So, for example if you have:

foreign import ccall "string.h strlen" cstrlen :: Ptr CChar -> IO CSize

fatype -> ftype :: ftype
   fatype :: fatype
     qtycon "Ptr"
     atype1 "CChar"
   fatype :: frtype
     qtycon "IO"
     atype1 "CSize"

(I struggled a bit with finding a good way to communicate the  
productions chosen, so bear with me)

Make sense?

-Ross


On Feb 10, 2009, at 6:13 PM, Maurí cio wrote:

>> The FFI spec says (at http://www.cse.unsw.edu.au/~chak/haskell/ffi/ffi/ffise3.html#x6-120003.2) 
>> :
>
> There I see:
>
> ---
> Foreign types are produced according to the following grammar:
>
> ftype  --> frtype
>       |   fatype -> ftype
> frtype --> fatype
>       |   ()
> fatype --> qtycon atype[1] ... atype[k] (k > 0)
> ---
>
> I can't understand the "qtycon atype[1]..." line. I did
> search haskell 98 report syntax reference, and saw how
> qtycon and tycon are defined, but I could not understand
> how they are used here.
>
> Thanks for your help,
> Maurício
>
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