On 11/2/11 7:14 AM, Eugene Kirpichov wrote:
I rewrote cFloatConv like this:
import GHC.Float
class (RealFloat a, RealFloat b) => CFloatConv a b where
cFloatConv :: a -> b
cFloatConv = realToFrac
instance CFloatConv Double Double where cFloatConv = id
instance CFloatConv Double CDouble
instance CFloatConv CDouble Double
instance CFloatConv Float Float where cFloatConv = id
instance CFloatConv Float Double where cFloatConv = float2Double
instance CFloatConv Double Float where cFloatConv = double2Float
If you're going the MPTC route, I suggest you use
logfloat:Data.Number.RealToFrac[1]. I don't have the CDouble and CFloat
instances, but I could add them. The instances themselves are only
moderately more clever than yours ---namely using CPP for portability to
non-GHC compilers--- but I think it's good for people to rally around
one implementation of the solution instead of having a bunch of copies
of the same thing, each poorly maintained because of the distributedness.
[1]
http://hackage.haskell.org/packages/archive/logfloat/0.12.1/doc/html/Data-Number-RealToFrac.html
--
Live well,
~wren
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