Why does sizeOf Word64 = 4?

[MartinNorbäck]

sön 2003-11-09 klockan 03.32 skrev Ben Escoto:
> Hi, I'm trying to learn about Haskell's FFI (running 6.0.1 on linux)
> and see the following weird behavior with ghci:
> 
> 	Prelude> :module Data.Word Foreign.Storable Foreign.Ptr
> 	Prelude Foreign.Ptr Foreign.Storable Data.Word> sizeOf nullPtr
> 	4
> 	Prelude Foreign.Ptr Foreign.Storable Data.Word> sizeOf
> 	                                          (nullPtr :: Ptr Word64)
> 	4
> 
> Shouldn't "sizeOf nullPtr" return an error?  And sizeOf a Ptr Word64
> should be 8 I think.

The size of a pointer is not the same as the size of what it points at.
On ia32 (x86) architectures, the size of a pointer is always 4 bytes (32
bits).

Regards,

	Martin