semigroupoids-5.3.1: Semigroupoids: Category sans id

Copyright(C) 2011-2015 Edward Kmett
LicenseBSD-style (see the file LICENSE)
MaintainerEdward Kmett <ekmett@gmail.com>
Stabilityprovisional
Portabilityportable
Safe HaskellTrustworthy
LanguageHaskell98

Data.Functor.Alt

Description

 
Synopsis

Documentation

class Functor f => Alt f where Source #

Laws:

<!> is associative:             (a <!> b) <!> c = a <!> (b <!> c)
<$> left-distributes over <!>:  f <$> (a <!> b) = (f <$> a) <!> (f <$> b)

If extended to an Alternative then <!> should equal <|>.

Ideally, an instance of Alt also satisfies the "left distributon" law of MonadPlus with respect to <.>:

<.> right-distributes over <!>: (a <!> b) <.> c = (a <.> c) <!> (b <.> c)

But Maybe, IO, Either a, ErrorT e m, and STM satisfy the alternative "left catch" law instead:

pure a <!> b = pure a

However, this variation cannot be stated purely in terms of the dependencies of Alt.

When and if MonadPlus is successfully refactored, this class should also be refactored to remove these instances.

The right distributive law should extend in the cases where the a Bind or Monad is provided to yield variations of the right distributive law:

(m <!> n) >>- f = (m >>- f) <!> (m >>- f)
(m <!> n) >>= f = (m >>= f) <!> (m >>= f)

Minimal complete definition

(<!>)

Methods

(<!>) :: f a -> f a -> f a infixl 3 Source #

<|> without a required empty

some :: Applicative f => f a -> f [a] Source #

many :: Applicative f => f a -> f [a] Source #

Instances
Alt [] Source # 
Instance details

Defined in Data.Functor.Alt

Methods

(<!>) :: [a] -> [a] -> [a] Source #

some :: Applicative [] => [a] -> [[a]] Source #

many :: Applicative [] => [a] -> [[a]] Source #

Alt Maybe Source # 
Instance details

Defined in Data.Functor.Alt

Methods

(<!>) :: Maybe a -> Maybe a -> Maybe a Source #

some :: Applicative Maybe => Maybe a -> Maybe [a] Source #

many :: Applicative Maybe => Maybe a -> Maybe [a] Source #

Alt IO Source #

This instance does not actually satisfy the (<.>) right distributive law It instead satisfies the "Left-Catch" law

Instance details

Defined in Data.Functor.Alt

Methods

(<!>) :: IO a -> IO a -> IO a Source #

some :: Applicative IO => IO a -> IO [a] Source #

many :: Applicative IO => IO a -> IO [a] Source #

Alt First Source # 
Instance details

Defined in Data.Functor.Alt

Methods

(<!>) :: First a -> First a -> First a Source #

some :: Applicative First => First a -> First [a] Source #

many :: Applicative First => First a -> First [a] Source #

Alt Last Source # 
Instance details

Defined in Data.Functor.Alt

Methods

(<!>) :: Last a -> Last a -> Last a Source #

some :: Applicative Last => Last a -> Last [a] Source #

many :: Applicative Last => Last a -> Last [a] Source #

Alt Option Source # 
Instance details

Defined in Data.Functor.Alt

Alt First Source # 
Instance details

Defined in Data.Functor.Alt

Methods

(<!>) :: First a -> First a -> First a Source #

some :: Applicative First => First a -> First [a] Source #

many :: Applicative First => First a -> First [a] Source #

Alt Last Source # 
Instance details

Defined in Data.Functor.Alt

Methods

(<!>) :: Last a -> Last a -> Last a Source #

some :: Applicative Last => Last a -> Last [a] Source #

many :: Applicative Last => Last a -> Last [a] Source #

Alt NonEmpty Source # 
Instance details

Defined in Data.Functor.Alt

Alt IntMap Source # 
Instance details

Defined in Data.Functor.Alt

Alt Seq Source # 
Instance details

Defined in Data.Functor.Alt

Methods

(<!>) :: Seq a -> Seq a -> Seq a Source #

some :: Applicative Seq => Seq a -> Seq [a] Source #

many :: Applicative Seq => Seq a -> Seq [a] Source #

Alt (Either a) Source # 
Instance details

Defined in Data.Functor.Alt

Methods

(<!>) :: Either a a0 -> Either a a0 -> Either a a0 Source #

some :: Applicative (Either a) => Either a a0 -> Either a [a0] Source #

many :: Applicative (Either a) => Either a a0 -> Either a [a0] Source #

Alt (V1 :: * -> *) Source # 
Instance details

Defined in Data.Functor.Alt

Methods

(<!>) :: V1 a -> V1 a -> V1 a Source #

some :: Applicative V1 => V1 a -> V1 [a] Source #

many :: Applicative V1 => V1 a -> V1 [a] Source #

Alt (U1 :: * -> *) Source # 
Instance details

Defined in Data.Functor.Alt

Methods

(<!>) :: U1 a -> U1 a -> U1 a Source #

some :: Applicative U1 => U1 a -> U1 [a] Source #

many :: Applicative U1 => U1 a -> U1 [a] Source #

MonadPlus m => Alt (WrappedMonad m) Source # 
Instance details

Defined in Data.Functor.Alt

Alt (Proxy :: * -> *) Source # 
Instance details

Defined in Data.Functor.Alt

Methods

(<!>) :: Proxy a -> Proxy a -> Proxy a Source #

some :: Applicative Proxy => Proxy a -> Proxy [a] Source #

many :: Applicative Proxy => Proxy a -> Proxy [a] Source #

Ord k => Alt (Map k) Source # 
Instance details

Defined in Data.Functor.Alt

Methods

(<!>) :: Map k a -> Map k a -> Map k a Source #

some :: Applicative (Map k) => Map k a -> Map k [a] Source #

many :: Applicative (Map k) => Map k a -> Map k [a] Source #

Alt f => Alt (Lift f) Source # 
Instance details

Defined in Data.Functor.Alt

Methods

(<!>) :: Lift f a -> Lift f a -> Lift f a Source #

some :: Applicative (Lift f) => Lift f a -> Lift f [a] Source #

many :: Applicative (Lift f) => Lift f a -> Lift f [a] Source #

(Bind f, Monad f) => Alt (MaybeT f) Source # 
Instance details

Defined in Data.Functor.Alt

Methods

(<!>) :: MaybeT f a -> MaybeT f a -> MaybeT f a Source #

some :: Applicative (MaybeT f) => MaybeT f a -> MaybeT f [a] Source #

many :: Applicative (MaybeT f) => MaybeT f a -> MaybeT f [a] Source #

Apply f => Alt (ListT f) Source # 
Instance details

Defined in Data.Functor.Alt

Methods

(<!>) :: ListT f a -> ListT f a -> ListT f a Source #

some :: Applicative (ListT f) => ListT f a -> ListT f [a] Source #

many :: Applicative (ListT f) => ListT f a -> ListT f [a] Source #

Alternative f => Alt (WrappedApplicative f) Source # 
Instance details

Defined in Data.Functor.Alt

Alt f => Alt (Rec1 f) Source # 
Instance details

Defined in Data.Functor.Alt

Methods

(<!>) :: Rec1 f a -> Rec1 f a -> Rec1 f a Source #

some :: Applicative (Rec1 f) => Rec1 f a -> Rec1 f [a] Source #

many :: Applicative (Rec1 f) => Rec1 f a -> Rec1 f [a] Source #

ArrowPlus a => Alt (WrappedArrow a b) Source # 
Instance details

Defined in Data.Functor.Alt

Methods

(<!>) :: WrappedArrow a b a0 -> WrappedArrow a b a0 -> WrappedArrow a b a0 Source #

some :: Applicative (WrappedArrow a b) => WrappedArrow a b a0 -> WrappedArrow a b [a0] Source #

many :: Applicative (WrappedArrow a b) => WrappedArrow a b a0 -> WrappedArrow a b [a0] Source #

Alt f => Alt (IdentityT f) Source # 
Instance details

Defined in Data.Functor.Alt

Alt f => Alt (Reverse f) Source # 
Instance details

Defined in Data.Functor.Alt

Methods

(<!>) :: Reverse f a -> Reverse f a -> Reverse f a Source #

some :: Applicative (Reverse f) => Reverse f a -> Reverse f [a] Source #

many :: Applicative (Reverse f) => Reverse f a -> Reverse f [a] Source #

Alt f => Alt (WriterT w f) Source # 
Instance details

Defined in Data.Functor.Alt

Methods

(<!>) :: WriterT w f a -> WriterT w f a -> WriterT w f a Source #

some :: Applicative (WriterT w f) => WriterT w f a -> WriterT w f [a] Source #

many :: Applicative (WriterT w f) => WriterT w f a -> WriterT w f [a] Source #

Alt f => Alt (WriterT w f) Source # 
Instance details

Defined in Data.Functor.Alt

Methods

(<!>) :: WriterT w f a -> WriterT w f a -> WriterT w f a Source #

some :: Applicative (WriterT w f) => WriterT w f a -> WriterT w f [a] Source #

many :: Applicative (WriterT w f) => WriterT w f a -> WriterT w f [a] Source #

Alt f => Alt (StateT e f) Source # 
Instance details

Defined in Data.Functor.Alt

Methods

(<!>) :: StateT e f a -> StateT e f a -> StateT e f a Source #

some :: Applicative (StateT e f) => StateT e f a -> StateT e f [a] Source #

many :: Applicative (StateT e f) => StateT e f a -> StateT e f [a] Source #

Alt f => Alt (StateT e f) Source # 
Instance details

Defined in Data.Functor.Alt

Methods

(<!>) :: StateT e f a -> StateT e f a -> StateT e f a Source #

some :: Applicative (StateT e f) => StateT e f a -> StateT e f [a] Source #

many :: Applicative (StateT e f) => StateT e f a -> StateT e f [a] Source #

(Bind f, Monad f, Semigroup e) => Alt (ExceptT e f) Source # 
Instance details

Defined in Data.Functor.Alt

Methods

(<!>) :: ExceptT e f a -> ExceptT e f a -> ExceptT e f a Source #

some :: Applicative (ExceptT e f) => ExceptT e f a -> ExceptT e f [a] Source #

many :: Applicative (ExceptT e f) => ExceptT e f a -> ExceptT e f [a] Source #

(Bind f, Monad f) => Alt (ErrorT e f) Source # 
Instance details

Defined in Data.Functor.Alt

Methods

(<!>) :: ErrorT e f a -> ErrorT e f a -> ErrorT e f a Source #

some :: Applicative (ErrorT e f) => ErrorT e f a -> ErrorT e f [a] Source #

many :: Applicative (ErrorT e f) => ErrorT e f a -> ErrorT e f [a] Source #

Alt f => Alt (Backwards f) Source # 
Instance details

Defined in Data.Functor.Alt

Alt f => Alt (Static f a) Source # 
Instance details

Defined in Data.Semigroupoid.Static

Methods

(<!>) :: Static f a a0 -> Static f a a0 -> Static f a a0 Source #

some :: Applicative (Static f a) => Static f a a0 -> Static f a [a0] Source #

many :: Applicative (Static f a) => Static f a a0 -> Static f a [a0] Source #

(Alt f, Alt g) => Alt (f :*: g) Source # 
Instance details

Defined in Data.Functor.Alt

Methods

(<!>) :: (f :*: g) a -> (f :*: g) a -> (f :*: g) a Source #

some :: Applicative (f :*: g) => (f :*: g) a -> (f :*: g) [a] Source #

many :: Applicative (f :*: g) => (f :*: g) a -> (f :*: g) [a] Source #

(Alt f, Alt g) => Alt (Product f g) Source # 
Instance details

Defined in Data.Functor.Alt

Methods

(<!>) :: Product f g a -> Product f g a -> Product f g a Source #

some :: Applicative (Product f g) => Product f g a -> Product f g [a] Source #

many :: Applicative (Product f g) => Product f g a -> Product f g [a] Source #

Alt f => Alt (ReaderT e f) Source # 
Instance details

Defined in Data.Functor.Alt

Methods

(<!>) :: ReaderT e f a -> ReaderT e f a -> ReaderT e f a Source #

some :: Applicative (ReaderT e f) => ReaderT e f a -> ReaderT e f [a] Source #

many :: Applicative (ReaderT e f) => ReaderT e f a -> ReaderT e f [a] Source #

Alt f => Alt (M1 i c f) Source # 
Instance details

Defined in Data.Functor.Alt

Methods

(<!>) :: M1 i c f a -> M1 i c f a -> M1 i c f a Source #

some :: Applicative (M1 i c f) => M1 i c f a -> M1 i c f [a] Source #

many :: Applicative (M1 i c f) => M1 i c f a -> M1 i c f [a] Source #

(Alt f, Functor g) => Alt (Compose f g) Source # 
Instance details

Defined in Data.Functor.Alt

Methods

(<!>) :: Compose f g a -> Compose f g a -> Compose f g a Source #

some :: Applicative (Compose f g) => Compose f g a -> Compose f g [a] Source #

many :: Applicative (Compose f g) => Compose f g a -> Compose f g [a] Source #

Alt f => Alt (RWST r w s f) Source # 
Instance details

Defined in Data.Functor.Alt

Methods

(<!>) :: RWST r w s f a -> RWST r w s f a -> RWST r w s f a Source #

some :: Applicative (RWST r w s f) => RWST r w s f a -> RWST r w s f [a] Source #

many :: Applicative (RWST r w s f) => RWST r w s f a -> RWST r w s f [a] Source #

Alt f => Alt (RWST r w s f) Source # 
Instance details

Defined in Data.Functor.Alt

Methods

(<!>) :: RWST r w s f a -> RWST r w s f a -> RWST r w s f a Source #

some :: Applicative (RWST r w s f) => RWST r w s f a -> RWST r w s f [a] Source #

many :: Applicative (RWST r w s f) => RWST r w s f a -> RWST r w s f [a] Source #

optional :: (Alt f, Applicative f) => f a -> f (Maybe a) Source #

One or none.