Dan Weston wrote:
Here, "any path" means all paths, a logical conjunction:
and [True, True] = True and [True ] = True and [ ] = True
Kim-Ee Yeoh wrote:
Hate to nitpick, but what appears to be some kind of a limit in the opposite direction is a curious way of arguing that: and [] = True.
Surely one can also write
and [False, False] = False and [False ] = False and [ ] = False ???
No. I think what Dan meant was that for all non-null xs :: [Bool], it is clearly true that: and (True:xs) == and xs -- (1) It therefore makes sense to define (1) to hold also for empty lists, and since it is also true that: and (True:[]) == True We obtain: and [] == True Since we can't make any similar claim about the conjuctions of lists beginning with False, there is no reasonable argument to the contrary.