One of the relationships implied by the Ord typeclass is:
a <= b = True iff compare a b = EQ \/ compare a b = LT
If we write an alternative definition of (<=) that is only strict in its
first argument:
False <= _ = True
True <= x = x
Then it's impossible to write `compare` in a way that's consistent with
that relation.
More concretely, it's likely that Ord Bool is defined via `compare`, which
is necessarily strict in both arguments.
On Wed, 2 Jan. 2019, 7:47 pm V.Liepelt,
I am surprised to find that `False <= undefined = undefined`.
What justifies (<=) to be strict in both arguments?
Vilem _______________________________________________ Haskell-Cafe mailing list To (un)subscribe, modify options or view archives go to: http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe Only members subscribed via the mailman list are allowed to post.