2011-02-23 13:56, Victor Nazarov skrev:
Also I think that value of hash functions is obviously a Monoid and it will be convenient to have Monoid instance
newtype Hash = Hash Int instance Monoid Hash where mempty = Hash 0 Hash a `mappend` Hash b = Hash (a `combine` b)
class Eq a => Hashable a where hash :: a -> Hash hashWithSalt :: Hash -> a -> Hash
hashWithSalt salt x = salt `mappend` hash x
Monoid would be a good idea if combine was associative :) Prelude Data.Hashable> let a = hash "a" Prelude Data.Hashable> let b = hash "b" Prelude Data.Hashable> let c = hash "c" Prelude Data.Hashable> (a `combine` b) `combine` c 198573605 Prelude Data.Hashable> a `combine` (b `combine` c) 177445 / Emil