Safe Haskell | None |
---|---|
Language | Haskell2010 |
Utilities for the Either
type.
Synopsis
- whileLeft :: Monad m => (a -> Either b c) -> (a -> b -> m a) -> (a -> c -> m d) -> a -> m d
- caseEitherM :: Monad m => m (Either a b) -> (a -> m c) -> (b -> m c) -> m c
- mapLeft :: (a -> c) -> Either a b -> Either c b
- mapRight :: (b -> d) -> Either a b -> Either a d
- traverseEither :: Functor f => (a -> f c) -> (b -> f d) -> Either a b -> f (Either c d)
- isLeft :: Either a b -> Bool
- isRight :: Either a b -> Bool
- fromLeft :: (b -> a) -> Either a b -> a
- fromRight :: (a -> b) -> Either a b -> b
- fromLeftM :: Monad m => (b -> m a) -> m (Either a b) -> m a
- fromRightM :: Monad m => (a -> m b) -> m (Either a b) -> m b
- maybeLeft :: Either a b -> Maybe a
- maybeRight :: Either a b -> Maybe b
- allLeft :: [Either a b] -> Maybe [a]
- allRight :: [Either a b] -> Maybe [b]
- groupByEither :: [Either a b] -> [Either (List1 a) (List1 b)]
- maybeToEither :: e -> Maybe a -> Either e a
- swapEither :: Either a b -> Either b a
Documentation
whileLeft :: Monad m => (a -> Either b c) -> (a -> b -> m a) -> (a -> c -> m d) -> a -> m d Source #
Loop while we have an exception.
caseEitherM :: Monad m => m (Either a b) -> (a -> m c) -> (b -> m c) -> m c Source #
Monadic version of either
with a different argument ordering.
traverseEither :: Functor f => (a -> f c) -> (b -> f d) -> Either a b -> f (Either c d) Source #
Either
is bitraversable.
Note: From base >= 4.10.0.0
already present in Bitraversable
.
fromLeftM :: Monad m => (b -> m a) -> m (Either a b) -> m a Source #
Analogue of fromMaybeM
.
fromRightM :: Monad m => (a -> m b) -> m (Either a b) -> m b Source #
Analogue of fromMaybeM
.
maybeLeft :: Either a b -> Maybe a Source #
Safe projection from Left
.
maybeLeft (Left a) = Just a maybeLeft Right{} = Nothing
maybeRight :: Either a b -> Maybe b Source #
Safe projection from Right
.
maybeRight (Right b) = Just b maybeRight Left{} = Nothing
groupByEither :: [Either a b] -> [Either (List1 a) (List1 b)] Source #
Groups a list into alternating chunks of Left
and Right
values
maybeToEither :: e -> Maybe a -> Either e a Source #
swapEither :: Either a b -> Either b a Source #
Swap tags Left
and Right
.