[Haskell-cafe] Multiple instancing of functions with FFI

[Ian Lynagh]

Hi Darrell,

On Mon, Jul 09, 2007 at 05:48:47PM -0700, Lewis-Sandy, Darrell wrote:
> I am having trouble exporting multiple instances of a polymorphic function
> similar to the example in the "Haskell 98 Foreign Function Interface 1.0
> addendum" (page 6).  My specific code is below:

Thanks for the detailed bug report!

I've put it in the bug tracker here:
http://hackage.haskell.org/trac/ghc/ticket/1533
milestoned to be fixed in the next release, and also added a test to the
testsuite for it.

> >foreign export stdcall "addByte" (+):: Int8->Int8->Int8
> >foreign export stdcall "addInt"  (+):: Int16->Int16->Int16
> >foreign export stdcall "addLong" (+):: Int32->Int32->Int32

In the mean time, as a workaround, you can use

    >addByte :: Int8->Int8->Int8
    >addByte = (+)
    >addInt  :: Int16->Int16->Int16
    >addInt  = (+)
    >addLong :: Int32->Int32->Int32
    >addLong = (+)

    >foreign export stdcall "addByte" addByte :: Int8->Int8->Int8
    >foreign export stdcall "addInt"  addInt  :: Int16->Int16->Int16
    >foreign export stdcall "addLong" addLong :: Int32->Int32->Int32


Thanks
Ian