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/Haskell 8

Control.Monad.Instances

Copyright (c) The University of Glasgow 2001
License BSD-style (see the file libraries/base/LICENSE)
Maintainer libraries@haskell.org
Stability provisional
Portability portable
Safe Haskell Safe
Language Haskell2010

Description

Deprecated: This module now contains no instances and will be removed in the future

This module is DEPRECATED and will be removed in the future!

Functor and Monad instances for (->) r and Functor instances for (,) a and Either a.

class Functor f where Source

The Functor class is used for types that can be mapped over. Instances of Functor should satisfy the following laws:

fmap id  ==  id
fmap (f . g)  ==  fmap f . fmap g

The instances of Functor for lists, Maybe and IO satisfy these laws.

Minimal complete definition

fmap

Methods

fmap :: (a -> b) -> f a -> f b Source

(<$) :: a -> f b -> f a infixl 4 Source

Replace all locations in the input with the same value. The default definition is fmap . const, but this may be overridden with a more efficient version.

Instances

Functor []

Methods

fmap :: (a -> b) -> [a] -> [b] Source

(<$) :: a -> [b] -> [a] Source

Functor Maybe

Methods

fmap :: (a -> b) -> Maybe a -> Maybe b Source

(<$) :: a -> Maybe b -> Maybe a Source

Functor IO

Methods

fmap :: (a -> b) -> IO a -> IO b Source

(<$) :: a -> IO b -> IO a Source

Functor V1

Methods

fmap :: (a -> b) -> V1 a -> V1 b Source

(<$) :: a -> V1 b -> V1 a Source

Functor U1

Methods

fmap :: (a -> b) -> U1 a -> U1 b Source

(<$) :: a -> U1 b -> U1 a Source

Functor Par1

Methods

fmap :: (a -> b) -> Par1 a -> Par1 b Source

(<$) :: a -> Par1 b -> Par1 a Source

Functor ReadP

Methods

fmap :: (a -> b) -> ReadP a -> ReadP b Source

(<$) :: a -> ReadP b -> ReadP a Source

Functor ReadPrec

Methods

fmap :: (a -> b) -> ReadPrec a -> ReadPrec b Source

(<$) :: a -> ReadPrec b -> ReadPrec a Source

Functor Last

Methods

fmap :: (a -> b) -> Last a -> Last b Source

(<$) :: a -> Last b -> Last a Source

Functor First

Methods

fmap :: (a -> b) -> First a -> First b Source

(<$) :: a -> First b -> First a Source

Functor Product

Methods

fmap :: (a -> b) -> Product a -> Product b Source

(<$) :: a -> Product b -> Product a Source

Functor Sum

Methods

fmap :: (a -> b) -> Sum a -> Sum b Source

(<$) :: a -> Sum b -> Sum a Source

Functor Dual

Methods

fmap :: (a -> b) -> Dual a -> Dual b Source

(<$) :: a -> Dual b -> Dual a Source

Functor STM

Methods

fmap :: (a -> b) -> STM a -> STM b Source

(<$) :: a -> STM b -> STM a Source

Functor Handler

Methods

fmap :: (a -> b) -> Handler a -> Handler b Source

(<$) :: a -> Handler b -> Handler a Source

Functor ZipList

Methods

fmap :: (a -> b) -> ZipList a -> ZipList b Source

(<$) :: a -> ZipList b -> ZipList a Source

Functor ArgDescr

Methods

fmap :: (a -> b) -> ArgDescr a -> ArgDescr b Source

(<$) :: a -> ArgDescr b -> ArgDescr a Source

Functor OptDescr

Methods

fmap :: (a -> b) -> OptDescr a -> OptDescr b Source

(<$) :: a -> OptDescr b -> OptDescr a Source

Functor ArgOrder

Methods

fmap :: (a -> b) -> ArgOrder a -> ArgOrder b Source

(<$) :: a -> ArgOrder b -> ArgOrder a Source

Functor Complex

Methods

fmap :: (a -> b) -> Complex a -> Complex b Source

(<$) :: a -> Complex b -> Complex a Source

Functor NonEmpty

Methods

fmap :: (a -> b) -> NonEmpty a -> NonEmpty b Source

(<$) :: a -> NonEmpty b -> NonEmpty a Source

Functor Option

Methods

fmap :: (a -> b) -> Option a -> Option b Source

(<$) :: a -> Option b -> Option a Source

Functor Last

Methods

fmap :: (a -> b) -> Last a -> Last b Source

(<$) :: a -> Last b -> Last a Source

Functor First

Methods

fmap :: (a -> b) -> First a -> First b Source

(<$) :: a -> First b -> First a Source

Functor Max

Methods

fmap :: (a -> b) -> Max a -> Max b Source

(<$) :: a -> Max b -> Max a Source

Functor Min

Methods

fmap :: (a -> b) -> Min a -> Min b Source

(<$) :: a -> Min b -> Min a Source

Functor Identity

Methods

fmap :: (a -> b) -> Identity a -> Identity b Source

(<$) :: a -> Identity b -> Identity a Source

Functor ((->) r)

Methods

fmap :: (a -> b) -> (r -> a) -> r -> b Source

(<$) :: a -> (r -> b) -> r -> a Source

Functor (Either a)

Methods

fmap :: (a -> b) -> Either a a -> Either a b Source

(<$) :: a -> Either a b -> Either a a Source

Functor f => Functor (Rec1 f)

Methods

fmap :: (a -> b) -> Rec1 f a -> Rec1 f b Source

(<$) :: a -> Rec1 f b -> Rec1 f a Source

Functor (URec Char)

Methods

fmap :: (a -> b) -> URec Char a -> URec Char b Source

(<$) :: a -> URec Char b -> URec Char a Source

Functor (URec Double)

Methods

fmap :: (a -> b) -> URec Double a -> URec Double b Source

(<$) :: a -> URec Double b -> URec Double a Source

Functor (URec Float)

Methods

fmap :: (a -> b) -> URec Float a -> URec Float b Source

(<$) :: a -> URec Float b -> URec Float a Source

Functor (URec Int)

Methods

fmap :: (a -> b) -> URec Int a -> URec Int b Source

(<$) :: a -> URec Int b -> URec Int a Source

Functor (URec Word)

Methods

fmap :: (a -> b) -> URec Word a -> URec Word b Source

(<$) :: a -> URec Word b -> URec Word a Source

Functor (URec (Ptr ()))

Methods

fmap :: (a -> b) -> URec (Ptr ()) a -> URec (Ptr ()) b Source

(<$) :: a -> URec (Ptr ()) b -> URec (Ptr ()) a Source

Functor ((,) a)

Methods

fmap :: (a -> b) -> (a, a) -> (a, b) Source

(<$) :: a -> (a, b) -> (a, a) Source

Functor (ST s)

Methods

fmap :: (a -> b) -> ST s a -> ST s b Source

(<$) :: a -> ST s b -> ST s a Source

Functor (Proxy *)

Methods

fmap :: (a -> b) -> Proxy * a -> Proxy * b Source

(<$) :: a -> Proxy * b -> Proxy * a Source

Arrow a => Functor (ArrowMonad a)

Methods

fmap :: (a -> b) -> ArrowMonad a a -> ArrowMonad a b Source

(<$) :: a -> ArrowMonad a b -> ArrowMonad a a Source

Monad m => Functor (WrappedMonad m)

Methods

fmap :: (a -> b) -> WrappedMonad m a -> WrappedMonad m b Source

(<$) :: a -> WrappedMonad m b -> WrappedMonad m a Source

Functor (ST s)

Methods

fmap :: (a -> b) -> ST s a -> ST s b Source

(<$) :: a -> ST s b -> ST s a Source

Functor (Arg a)

Methods

fmap :: (a -> b) -> Arg a a -> Arg a b Source

(<$) :: a -> Arg a b -> Arg a a Source

Functor (K1 i c)

Methods

fmap :: (a -> b) -> K1 i c a -> K1 i c b Source

(<$) :: a -> K1 i c b -> K1 i c a Source

(Functor f, Functor g) => Functor ((:+:) f g)

Methods

fmap :: (a -> b) -> (f :+: g) a -> (f :+: g) b Source

(<$) :: a -> (f :+: g) b -> (f :+: g) a Source

(Functor f, Functor g) => Functor ((:*:) f g)

Methods

fmap :: (a -> b) -> (f :*: g) a -> (f :*: g) b Source

(<$) :: a -> (f :*: g) b -> (f :*: g) a Source

(Functor f, Functor g) => Functor ((:.:) f g)

Methods

fmap :: (a -> b) -> (f :.: g) a -> (f :.: g) b Source

(<$) :: a -> (f :.: g) b -> (f :.: g) a Source

Functor f => Functor (Alt * f)

Methods

fmap :: (a -> b) -> Alt * f a -> Alt * f b Source

(<$) :: a -> Alt * f b -> Alt * f a Source

Functor (Const * m)

Methods

fmap :: (a -> b) -> Const * m a -> Const * m b Source

(<$) :: a -> Const * m b -> Const * m a Source

Arrow a => Functor (WrappedArrow a b)

Methods

fmap :: (a -> b) -> WrappedArrow a b a -> WrappedArrow a b b Source

(<$) :: a -> WrappedArrow a b b -> WrappedArrow a b a Source

Functor f => Functor (M1 i c f)

Methods

fmap :: (a -> b) -> M1 i c f a -> M1 i c f b Source

(<$) :: a -> M1 i c f b -> M1 i c f a Source

(Functor f, Functor g) => Functor (Product * f g)

Methods

fmap :: (a -> b) -> Product * f g a -> Product * f g b Source

(<$) :: a -> Product * f g b -> Product * f g a Source

(Functor f, Functor g) => Functor (Sum * f g)

Methods

fmap :: (a -> b) -> Sum * f g a -> Sum * f g b Source

(<$) :: a -> Sum * f g b -> Sum * f g a Source

(Functor f, Functor g) => Functor (Compose * * f g)

Methods

fmap :: (a -> b) -> Compose * * f g a -> Compose * * f g b Source

(<$) :: a -> Compose * * f g b -> Compose * * f g a Source

class Applicative m => Monad m where Source

The Monad class defines the basic operations over a monad, a concept from a branch of mathematics known as category theory. From the perspective of a Haskell programmer, however, it is best to think of a monad as an abstract datatype of actions. Haskell's do expressions provide a convenient syntax for writing monadic expressions.

Instances of Monad should satisfy the following laws:

Furthermore, the Monad and Applicative operations should relate as follows:

The above laws imply:

and that pure and (<*>) satisfy the applicative functor laws.

The instances of Monad for lists, Maybe and IO defined in the Prelude satisfy these laws.

Minimal complete definition

(>>=)

Methods

(>>=) :: forall a b. m a -> (a -> m b) -> m b infixl 1 Source

Sequentially compose two actions, passing any value produced by the first as an argument to the second.

(>>) :: forall a b. m a -> m b -> m b infixl 1 Source

Sequentially compose two actions, discarding any value produced by the first, like sequencing operators (such as the semicolon) in imperative languages.

return :: a -> m a Source

Inject a value into the monadic type.

fail :: String -> m a Source

Fail with a message. This operation is not part of the mathematical definition of a monad, but is invoked on pattern-match failure in a do expression.

As part of the MonadFail proposal (MFP), this function is moved to its own class MonadFail (see Control.Monad.Fail for more details). The definition here will be removed in a future release.

Instances

Monad []

Methods

(>>=) :: [a] -> (a -> [b]) -> [b] Source

(>>) :: [a] -> [b] -> [b] Source

return :: a -> [a] Source

fail :: String -> [a] Source

Monad Maybe

Methods

(>>=) :: Maybe a -> (a -> Maybe b) -> Maybe b Source

(>>) :: Maybe a -> Maybe b -> Maybe b Source

return :: a -> Maybe a Source

fail :: String -> Maybe a Source

Monad IO

Methods

(>>=) :: IO a -> (a -> IO b) -> IO b Source

(>>) :: IO a -> IO b -> IO b Source

return :: a -> IO a Source

fail :: String -> IO a Source

Monad U1

Methods

(>>=) :: U1 a -> (a -> U1 b) -> U1 b Source

(>>) :: U1 a -> U1 b -> U1 b Source

return :: a -> U1 a Source

fail :: String -> U1 a Source

Monad Par1

Methods

(>>=) :: Par1 a -> (a -> Par1 b) -> Par1 b Source

(>>) :: Par1 a -> Par1 b -> Par1 b Source

return :: a -> Par1 a Source

fail :: String -> Par1 a Source

Monad ReadP

Methods

(>>=) :: ReadP a -> (a -> ReadP b) -> ReadP b Source

(>>) :: ReadP a -> ReadP b -> ReadP b Source

return :: a -> ReadP a Source

fail :: String -> ReadP a Source

Monad ReadPrec

Methods

(>>=) :: ReadPrec a -> (a -> ReadPrec b) -> ReadPrec b Source

(>>) :: ReadPrec a -> ReadPrec b -> ReadPrec b Source

return :: a -> ReadPrec a Source

fail :: String -> ReadPrec a Source

Monad Last

Methods

(>>=) :: Last a -> (a -> Last b) -> Last b Source

(>>) :: Last a -> Last b -> Last b Source

return :: a -> Last a Source

fail :: String -> Last a Source

Monad First

Methods

(>>=) :: First a -> (a -> First b) -> First b Source

(>>) :: First a -> First b -> First b Source

return :: a -> First a Source

fail :: String -> First a Source

Monad Product

Methods

(>>=) :: Product a -> (a -> Product b) -> Product b Source

(>>) :: Product a -> Product b -> Product b Source

return :: a -> Product a Source

fail :: String -> Product a Source

Monad Sum

Methods

(>>=) :: Sum a -> (a -> Sum b) -> Sum b Source

(>>) :: Sum a -> Sum b -> Sum b Source

return :: a -> Sum a Source

fail :: String -> Sum a Source

Monad Dual

Methods

(>>=) :: Dual a -> (a -> Dual b) -> Dual b Source

(>>) :: Dual a -> Dual b -> Dual b Source

return :: a -> Dual a Source

fail :: String -> Dual a Source

Monad STM

Methods

(>>=) :: STM a -> (a -> STM b) -> STM b Source

(>>) :: STM a -> STM b -> STM b Source

return :: a -> STM a Source

fail :: String -> STM a Source

Monad Complex

Methods

(>>=) :: Complex a -> (a -> Complex b) -> Complex b Source

(>>) :: Complex a -> Complex b -> Complex b Source

return :: a -> Complex a Source

fail :: String -> Complex a Source

Monad NonEmpty

Methods

(>>=) :: NonEmpty a -> (a -> NonEmpty b) -> NonEmpty b Source

(>>) :: NonEmpty a -> NonEmpty b -> NonEmpty b Source

return :: a -> NonEmpty a Source

fail :: String -> NonEmpty a Source

Monad Option

Methods

(>>=) :: Option a -> (a -> Option b) -> Option b Source

(>>) :: Option a -> Option b -> Option b Source

return :: a -> Option a Source

fail :: String -> Option a Source

Monad Last

Methods

(>>=) :: Last a -> (a -> Last b) -> Last b Source

(>>) :: Last a -> Last b -> Last b Source

return :: a -> Last a Source

fail :: String -> Last a Source

Monad First

Methods

(>>=) :: First a -> (a -> First b) -> First b Source

(>>) :: First a -> First b -> First b Source

return :: a -> First a Source

fail :: String -> First a Source

Monad Max

Methods

(>>=) :: Max a -> (a -> Max b) -> Max b Source

(>>) :: Max a -> Max b -> Max b Source

return :: a -> Max a Source

fail :: String -> Max a Source

Monad Min

Methods

(>>=) :: Min a -> (a -> Min b) -> Min b Source

(>>) :: Min a -> Min b -> Min b Source

return :: a -> Min a Source

fail :: String -> Min a Source

Monad Identity

Methods

(>>=) :: Identity a -> (a -> Identity b) -> Identity b Source

(>>) :: Identity a -> Identity b -> Identity b Source

return :: a -> Identity a Source

fail :: String -> Identity a Source

Monad ((->) r)

Methods

(>>=) :: (r -> a) -> (a -> r -> b) -> r -> b Source

(>>) :: (r -> a) -> (r -> b) -> r -> b Source

return :: a -> r -> a Source

fail :: String -> r -> a Source

Monad (Either e)

Methods

(>>=) :: Either e a -> (a -> Either e b) -> Either e b Source

(>>) :: Either e a -> Either e b -> Either e b Source

return :: a -> Either e a Source

fail :: String -> Either e a Source

Monad f => Monad (Rec1 f)

Methods

(>>=) :: Rec1 f a -> (a -> Rec1 f b) -> Rec1 f b Source

(>>) :: Rec1 f a -> Rec1 f b -> Rec1 f b Source

return :: a -> Rec1 f a Source

fail :: String -> Rec1 f a Source

Monoid a => Monad ((,) a)

Methods

(>>=) :: (a, a) -> (a -> (a, b)) -> (a, b) Source

(>>) :: (a, a) -> (a, b) -> (a, b) Source

return :: a -> (a, a) Source

fail :: String -> (a, a) Source

Monad (ST s)

Methods

(>>=) :: ST s a -> (a -> ST s b) -> ST s b Source

(>>) :: ST s a -> ST s b -> ST s b Source

return :: a -> ST s a Source

fail :: String -> ST s a Source

Monad (Proxy *)

Methods

(>>=) :: Proxy * a -> (a -> Proxy * b) -> Proxy * b Source

(>>) :: Proxy * a -> Proxy * b -> Proxy * b Source

return :: a -> Proxy * a Source

fail :: String -> Proxy * a Source

ArrowApply a => Monad (ArrowMonad a)

Methods

(>>=) :: ArrowMonad a a -> (a -> ArrowMonad a b) -> ArrowMonad a b Source

(>>) :: ArrowMonad a a -> ArrowMonad a b -> ArrowMonad a b Source

return :: a -> ArrowMonad a a Source

fail :: String -> ArrowMonad a a Source

Monad m => Monad (WrappedMonad m)

Methods

(>>=) :: WrappedMonad m a -> (a -> WrappedMonad m b) -> WrappedMonad m b Source

(>>) :: WrappedMonad m a -> WrappedMonad m b -> WrappedMonad m b Source

return :: a -> WrappedMonad m a Source

fail :: String -> WrappedMonad m a Source

Monad (ST s)

Methods

(>>=) :: ST s a -> (a -> ST s b) -> ST s b Source

(>>) :: ST s a -> ST s b -> ST s b Source

return :: a -> ST s a Source

fail :: String -> ST s a Source

(Monad f, Monad g) => Monad ((:*:) f g)

Methods

(>>=) :: (f :*: g) a -> (a -> (f :*: g) b) -> (f :*: g) b Source

(>>) :: (f :*: g) a -> (f :*: g) b -> (f :*: g) b Source

return :: a -> (f :*: g) a Source

fail :: String -> (f :*: g) a Source

Monad f => Monad (Alt * f)

Methods

(>>=) :: Alt * f a -> (a -> Alt * f b) -> Alt * f b Source

(>>) :: Alt * f a -> Alt * f b -> Alt * f b Source

return :: a -> Alt * f a Source

fail :: String -> Alt * f a Source

Monad f => Monad (M1 i c f)

Methods

(>>=) :: M1 i c f a -> (a -> M1 i c f b) -> M1 i c f b Source

(>>) :: M1 i c f a -> M1 i c f b -> M1 i c f b Source

return :: a -> M1 i c f a Source

fail :: String -> M1 i c f a Source

(Monad f, Monad g) => Monad (Product * f g)

Methods

(>>=) :: Product * f g a -> (a -> Product * f g b) -> Product * f g b Source

(>>) :: Product * f g a -> Product * f g b -> Product * f g b Source

return :: a -> Product * f g a Source

fail :: String -> Product * f g a Source

© The University of Glasgow and others
Licensed under a BSD-style license (see top of the page).
https://downloads.haskell.org/~ghc/8.0.1/docs/html/libraries/base-4.9.0.0/Control-Monad-Instances.html