Ferenc Wagner wrote: > "Simon Peyton-Jones" <[EMAIL PROTECTED]> writes: > > > So I propose to modify the instance decl for Ratio by > > adding explicit defns for succ/pred just like those in > > Float/Double. > > I bet you guessed: once at it, what about removing those > unintuitive 1/2-s, like: > > numericEnumFromTo n m = takeWhile (<= m) (numericEnumFrom n) > numericEnumFromThenTo n n' m = takeWhile p (numericEnumFromThen n n') > where > p | n' > n = (<= m + (n'-n)) > | otherwise = (>= m + (n'-n)) > > Everybody working with floats should know their quirks, while > Rationals should be treated exactly.
It's inconsistent to remove the "+1/2" for numericEnumFromTo but to leave the "+(n'-n)" for numericEnumFromThenTo. I think you probably mean to remove both (actually, all three). I wouldn't recommend these changes for Float and Double (the increments are there to account for arithmetic inexactness), but they do make a lot of sense to me for (Ratio a), which is exact. Is is too late to consider such a change? -- Dean _______________________________________________ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
