| classes: | |
| documentation: | |
| name: |
Control.Monad.Extra |
| operations: |
concatMapM mapAccumM |
| sourcecode: |
module Control.Monad.Extra where
--- Same as `concatMap`, but for a monadic function.
concatMapM :: Monad m => (a -> m [b]) -> [a] -> m [b]
concatMapM f xs = concat <$> mapM f xs
--- Same as `mapM` but with an additional accumulator threaded through.
mapAccumM :: Monad m => (a -> b -> m (a, c))
-> a -> [b] -> m (a, [c])
mapAccumM _ s [] = return (s, [])
mapAccumM f s (x : xs) = f s x >>= (\(s', x') -> (mapAccumM f s' xs) >>=
(\(s'', xs') -> return (s'', x' : xs')))
|
| types: | |
| unsafe: |
safe |