Re: [Haskell-cafe] Accumulator value for "and" and "or"

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