[Haskell-cafe] curious about sum

[Stephan Friedrichs]

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
  (+) = (++)

Regards,
Stephan

-- 

Früher hieß es ja: Ich denke, also bin ich.
Heute weiß man: Es geht auch so.

 - Dieter Nuhr