[Haskell-beginners] maximum: stack overflow?

[Roland Zumkeller]

Hi Alex,

On Fri, Mar 13, 2009 at 12:43 AM, Alexander Dunlap
<alexander.dunlap at gmail.com> wrote:
> Isn't maximum always (semantically) strict anyway? I.e.
>
> maximum [1,2,undefined] = undefined

If max is (semantically) strict, then so is maximum.
On the other hand, both may be non-strict:

> data Switch = Off | On deriving (Eq, Show)

> instance Ord Switch where
>   On <= Off = False
>   _  <= _   = True
>   max _ On  = On
>   max a Off = a

*Main> maximum [undefined,Off,On]
On
*Main> foldl1' max [undefined,Off,On]
*** Exception: Prelude.undefined

Best,

Roland

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