Extra.hs

-- | Extra Maybe utilities.

module Data.Maybe.Extra where

import Control.Applicative
import Control.Monad
import Data.Traversable hiding (mapM)
import Data.Maybe
import Prelude -- Silence redundant import warnings

-- | Applicative 'mapMaybe'.
mapMaybeA :: Applicative f => (a -> f (Maybe b)) -> [a] -> f [b]
mapMaybeA f = fmap catMaybes . traverse f

-- | @'forMaybeA' '==' 'flip' 'mapMaybeA'@
forMaybeA :: Applicative f => [a] -> (a -> f (Maybe b)) -> f [b]
forMaybeA = flip mapMaybeA

-- | Monadic 'mapMaybe'.
mapMaybeM :: Monad m => (a -> m (Maybe b)) -> [a] -> m [b]
mapMaybeM f = liftM catMaybes . mapM f

-- | @'forMaybeM' '==' 'flip' 'mapMaybeM'@
forMaybeM :: Monad m => [a] -> (a -> m (Maybe b)) -> m [b]
forMaybeM = flip mapMaybeM