Aaron Denney wrote:
On 2008-03-11, Adrian Hey <[EMAIL PROTECTED]> wrote:
Having tried this approach myself too (with the clone) I can confirm
that *this way lies madness*, so in future I will not be making
any effort to define or respect "sane", unambiguous and stable behaviour
for "insane" Eq/Ord instances for any lib I produce or hack on. Instead
I will be aiming for correctness and optimal efficiency on the
assumption that Eq and Ord instances are sensible.
Good. But sensible only means that the Eq and Ord instances agree, not that
x == y => f x == f y.
So can I assume that max x y = max y x?
If not, how can I tell if I've made the correct choice of argument
order. If I can't tell then I guess I have no alternative but document
my arbitrary choice in the Haddock, and probably for the (sake of
completeness) provide 2 or more alternative definitions of the "same"
function which use a different argument order.
Regards
--
Adrian Hey
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