On Thursday 31 March 2011 23:34:47, Henning Thielemann wrote:
On Thu, 31 Mar 2011, Daniel Fischer wrote:
Summary:
I propose - adding modules implementing integer logarithm functions to integer-gmp and integer-simple - changing the implementation of toRational and fromRational for Double and Float using those to become significantly faster.
Is there also a rule to, say, convert fromRational . toRational :: Double -> Double to 'id'? Sure 'id' is not quite correct because of NaNs. Maybe 'realToFrac'.
There are already rules for realToFrac, but afaik, not for (fromRational . toRational). But if those rules don't fire, you get realToFrac = fromRational . toRational, which is horrible for performance (and the conversion is less truthful than id/double2Float/float2Double which you get from the rules, so you probably don't really want the standard-conforming realToFrac for these conversions, but if you get it, does it have to be so slow?).