[Haskell-cafe] GHC optimisations

Neil Mitchell ndmitchell at gmail.com
Thu Aug 23 08:17:11 EDT 2007


> Its (==) isn't
> reflexive (is it transitive? probably, at least if there aren't too many
> optimizations, but floating-point transitive equality isn't very useful).

It's not even referentially transparent in all cases. a == b may fail
while the double's are in the high precision registers, and then
succeed later on in the program once they are truncated. I think you
have to specify -fexcess-precision with GHC to get this behaviour.



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