PR Stanley wrote:
Hi
or = foldl (||) False
and = foldl (&&) True
I can understand the rationale for the accumulator value - True && []
where [] = True and True || [] where [] = False
Other than the practical convenience is there a reason for having the
empty list in and and or equating to True and False?
Thanks, Paul
Another way to think about this is to look at
> any p = or . map p
> all p = and . map p
Now, "all even []" should hold, since everything in that list is even.
But not "any even []" because there is no even number in the empty list.
Twan
_______________________________________________
Haskell-Cafe mailing list
[email protected]
http://www.haskell.org/mailman/listinfo/haskell-cafe
