1 Nov
2004
1 Nov
'04
2:32 p.m.
Finn Wilcox wrote:
On Mon, 1 Nov 2004, Ben Rudiak-Gould wrote:
In particular, one cannot write an invert :: (a->b) -> Maybe (b->a) which never returns a wrong answer, except for invert = const Nothing
How about:
invert = undefined
This never returns an answer at all, so it can't return a wrong one!
Sorry, I should have been clearer: my Nothing return was intended to mean "I don't know an answer", not "there is no answer". So my const Nothing is like your undefined, a function which never returns an answer (and thus never returns a wrong one). -- Ben