2011/12/29 Manfred Lotz
Hi there, might be trivial but anyway.
I have a usage of 'any' and 'all' but I only have a predicate p :: a -> IO Bool.
I wrote my own functons for this:
mor :: Monad m => [m Bool] -> m Bool mor = liftM or . sequence
mand :: Monad m => [m Bool] -> m Bool mand = liftM and . sequence
or' :: Monad m => ( a -> m Bool) -> [a] -> [m Bool] or' _ [] = [] or' p (x:xs) = p x : or' p xs
and' :: Monad m => ( a -> m Bool) -> [a] -> [m Bool] and' _ [] = [] and' p (x:xs) = p x : and' p xs
myany :: Monad m => (a -> m Bool) -> [a] -> m Bool myany p = mor . or' p
myall :: Monad m => (a -> m Bool) -> [a] -> m Bool myall p = mand . and' p
which seems to do what I want.
Question: Is there any libray function I could use to do this?
-- Thanks, Manfred
Hi Manfred, have a look here: http://hackage.haskell.org/packages/archive/monad-loops/latest/doc/html/Cont... Regards Tim