[Haskell-cafe] Overriding a Prelude function?

[Luke Palmer]

On Thu, Apr 23, 2009 at 1:34 PM, Miguel Mitrofanov <miguelimo38 at yandex.ru>wrote:

>
> Well, than, what would you expect from this:
>
> let {f x = g x;
>      g 0 = 0;
>      g n = f (n-1)}
> in show f


Well, not show, because any show instance for functions breaks r.t.  But the
interactive interpreter, if it is not subject to r.t., might show:

let { f x = g x;
      g 0 = 0;
      g n = f (n-1) } in f

Or

fst (fix (\~(f,g) -> (\x -> g x, \n -> case n of { 0 -> 0; n -> f (n-1) })))

Or any number of other equivalent writings.

Luke
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