[Haskell-cafe] sizeOf on a type

Patai Gergely patai_gergely at fastmail.fm
Fri Dec 18 15:09:30 EST 2009


> I would like to write a routine like
> 	nextPtr :: Storable a => Ptr a -> Ptr a
> 	nextPtr = (`plusPtr` sizeOf (undefined :: a))
> which increments a pointer by the correct amount, but
> GHC complains that the type variable "a" is ambiguous.

Maybe Foreign.Marshal.Array.advancePtr is what you really need in this


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