Am Sonntag, 14. Mai 2006 09:30 schrieb SevenThunders:
I am new to Haskell and found myself in a bind concerning the use of the C types, CDouble in particular. I extract a CDouble via it's pointer from a StorableArray. Since the array must interface with C the elements of the array must be CDouble. Now I'd like to use Text.Printf to format print statements of elements of the array, but Text.Printf requires Doubles as inputs and so far I have not found an obvious way to coerce CDoubles into Doubles. [...]
You can use the Prelude function realToFrac to convert between the various floating-point types: ---------------------------------------------------------------- panne@jeanluc:~> ghci -v0 Prelude> :t realToFrac realToFrac :: (Fractional t1, Real t) => t -> t1 Prelude> (realToFrac :: Foreign.C.Types.CDouble -> Double) 1234.5 1234.5 ---------------------------------------------------------------- As you can see from its type, realToFrac is not exactly about floating-point conversions, but for almost all practical use cases it is. :-) Cheers, S.