[Haskell-cafe] curious about sum
deduktionstheorem at web.de
Sat Jun 13 10:26:49 EDT 2009
Jochem Berndsen wrote:
> 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.
What about some numeric representations?
type MyNum = [()]
instance Num MyNum where
(+) = (++)
Früher hieß es ja: Ich denke, also bin ich.
Heute weiß man: Es geht auch so.
- Dieter Nuhr
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