Safe Haskell	Safe
Language	Haskell2010

Data.Choice

Synopsis

Documentation

data Choice a b Source #

Choice is a version of Either that is strict on both the Left side (called This) and the Right side (called That).

Note: Choice is not used as an error monad. Use Fail for that.

Constructors

This !a
That !b

Instances

Bifunctor Choice Source #
Methods bimap :: (a -> b) -> (c -> d) -> Choice a c -> Choice b d # first :: (a -> b) -> Choice a c -> Choice b c # second :: (b -> c) -> Choice a b -> Choice a c #
Monad (Choice e) Source #
Methods (>>=) :: Choice e a -> (a -> Choice e b) -> Choice e b # (>>) :: Choice e a -> Choice e b -> Choice e b # return :: a -> Choice e a # fail :: String -> Choice e a #
Functor (Choice a) Source #
Methods fmap :: (a -> b) -> Choice a a -> Choice a b # (<$) :: a -> Choice a b -> Choice a a #
Applicative (Choice e) Source #
Methods pure :: a -> Choice e a # (<>) :: Choice e (a -> b) -> Choice e a -> Choice e b # (>) :: Choice e a -> Choice e b -> Choice e b # (<*) :: Choice e a -> Choice e b -> Choice e a #
(Eq b, Eq a) => Eq (Choice a b) Source #
Methods (==) :: Choice a b -> Choice a b -> Bool # (/=) :: Choice a b -> Choice a b -> Bool #
(Data b, Data a) => Data (Choice a b) Source #
Methods gfoldl :: (forall d c. Data d => c (d -> c) -> d -> c c) -> (forall g. g -> c g) -> Choice a b -> c (Choice a b) # gunfold :: (forall c r. Data c => c (c -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (Choice a b) # toConstr :: Choice a b -> Constr # dataTypeOf :: Choice a b -> DataType # dataCast1 :: Typeable (* -> ) t => (forall d. Data d => c (t d)) -> Maybe (c (Choice a b)) # dataCast2 :: Typeable ( -> * -> *) t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Choice a b)) # gmapT :: (forall c. Data c => c -> c) -> Choice a b -> Choice a b # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Choice a b -> r # gmapQr :: (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Choice a b -> r # gmapQ :: (forall d. Data d => d -> u) -> Choice a b -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> Choice a b -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Choice a b -> m (Choice a b) # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Choice a b -> m (Choice a b) # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Choice a b -> m (Choice a b) #
(Ord b, Ord a) => Ord (Choice a b) Source #
Methods compare :: Choice a b -> Choice a b -> Ordering # (<) :: Choice a b -> Choice a b -> Bool # (<=) :: Choice a b -> Choice a b -> Bool # (>) :: Choice a b -> Choice a b -> Bool # (>=) :: Choice a b -> Choice a b -> Bool # max :: Choice a b -> Choice a b -> Choice a b # min :: Choice a b -> Choice a b -> Choice a b #
(Read b, Read a) => Read (Choice a b) Source #
Methods readsPrec :: Int -> ReadS (Choice a b) # readList :: ReadS [Choice a b] # readPrec :: ReadPrec (Choice a b) # readListPrec :: ReadPrec [Choice a b] #
(Show b, Show a) => Show (Choice a b) Source #
Methods showsPrec :: Int -> Choice a b -> ShowS # show :: Choice a b -> String # showList :: [Choice a b] -> ShowS #
(Arbitrary a, Arbitrary b) => Arbitrary (Choice a b) Source #
Methods arbitrary :: Gen (Choice a b) # shrink :: Choice a b -> [Choice a b] #
(Hashable a, Hashable b) => Hashable (Choice a b) Source #
Methods hashWithSalt :: Int -> Choice a b -> Int # hash :: Choice a b -> Int #
(NFData a, NFData b) => NFData (Choice a b) Source #
Methods rnf :: Choice a b -> () #

choice :: (a -> c) -> (b -> c) -> Choice a b -> c Source #

Choice's version of either

this :: Monad m => Choice a b -> m a Source #

>>> this (This "foo") :: Maybe String
Just "foo"

>>> this (That "bar") :: Maybe String
Nothing

that :: Monad m => Choice a b -> m b Source #

>>> that (This "foo") :: Maybe String
Nothing

>>> that (That "bar") :: Maybe String
Just "bar"

these :: [Choice a b] -> [a] Source #

>>> these [This "foo", This "bar", That "baz", This "quux"]
["foo","bar","quux"]

those :: [Choice a b] -> [b] Source #

>>> those [This "foo", This "bar", That "baz", This "quux"]
["baz"]

eitherToChoice :: Either a b -> Choice a b Source #

>>> eitherToChoice (Left 1)
This 1

>>> eitherToChoice (Right 5)
That 5

mergeChoice :: Choice a a -> a Source #

>>> mergeChoice (This 5 :: Choice Int Int)
5

>>> mergeChoice (That 'c' :: Choice Char Char)
'c'