On Dec 19, 2007 7:26 PM, jlw501
I'm new to functional programming and Haskell and I love its expressive ability! I've been trying to formalize the following function for time. Given people and a piece of information, can all people know the same thing? Anyway, this is just a bit of fun... but can anyone help me reduce it or talk about strictness and junk as I'd like to make a blog on it?
This looks like an encoding of some philosophical problem or something. I don't really follow. I'll comment anyway.
contains :: Eq a => [a]->a->Bool contains [] e = False contains (x:xs) e = if x==e then True else contains xs e
contains = flip elem
perfectcomm :: Bool perfectcomm = undefined knowself :: Bool knowself = undefined
Why are these undefined?
allKnow :: Eq a => [a]->String->Bool allKnow _ "" = True allKnow [] k = False allKnow (x:[]) k = knowself allKnow (x:xs) k = comm x xs k && allKnow xs k where comm p [] k = False
This case will never be reached, because you match against (x:[]) first.
comm p ps k = if contains ps p then knowself else perfectcomm
And I don't understand the logic here. :-p Luke