2009/6/13 Jochem Berndsen <joc...@functor.nl>: > Keith Sheppard wrote: >> Is there any reason that sum isn't strict? I can't think of any case >> where that is a good thing. >> >> Prelude> sum [0 .. 1000000] >> *** Exception: stack overflow > > It is useful if the (+) is nonstrict; although I cannot think of any > useful mathematical structure where (+) would be nonstrict.
I remember needing a non-strict sum at least once, but I do not remember the exact application. But imagine having a (very) long list of numbers and you want to do A if the sum exceeds a small number, otherwise B. if sum [0..100000] > 10 then A else B However, this idea didn't work, because of strictness. -- Deniz Dogan _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
