Rational sequence
Ferenc Wagner
wferi@afavant.elte.hu
Thu, 24 Oct 2002 16:50:14 +0200
"Simon Peyton-Jones" <simonpj@microsoft.com> 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.
Feri.