| 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 | 
Control.Monad.Instances
Description
Documentation
class Functor f where Source #
A type f is a Functor if it provides a function fmap which, given any types a and b
lets you apply any function from (a -> b) to turn an f a into an f b, preserving the
structure of f. Furthermore f needs to adhere to the following laws:
Minimal complete definition
Instances
| Functor [] Source # | Since: base-2.1 | 
| Functor Maybe Source # | Since: base-2.1 | 
| Functor IO Source # | Since: base-2.1 | 
| Functor Par1 Source # | Since: base-4.9.0.0 | 
| Functor NonEmpty Source # | Since: base-4.9.0.0 | 
| Functor ReadP Source # | Since: base-2.1 | 
| Functor ReadPrec Source # | Since: base-2.1 | 
| Functor Down Source # | Since: base-4.11.0.0 | 
| Functor Product Source # | Since: base-4.8.0.0 | 
| Functor Sum Source # | Since: base-4.8.0.0 | 
| Functor Dual Source # | Since: base-4.8.0.0 | 
| Functor Last Source # | Since: base-4.8.0.0 | 
| Functor First Source # | Since: base-4.8.0.0 | 
| Functor STM Source # | Since: base-4.3.0.0 | 
| Functor Handler Source # | Since: base-4.6.0.0 | 
| Functor Identity Source # | Since: base-4.8.0.0 | 
| Functor ZipList Source # | Since: base-2.1 | 
| Functor ArgDescr Source # | Since: base-4.6.0.0 | 
| Functor OptDescr Source # | Since: base-4.6.0.0 | 
| Functor ArgOrder Source # | Since: base-4.6.0.0 | 
| Functor Option Source # | Since: base-4.9.0.0 | 
| Functor Last Source # | Since: base-4.9.0.0 | 
| Functor First Source # | Since: base-4.9.0.0 | 
| Functor Max Source # | Since: base-4.9.0.0 | 
| Functor Min Source # | Since: base-4.9.0.0 | 
| Functor Complex Source # | Since: base-4.9.0.0 | 
| Functor (Either a) Source # | Since: base-3.0 | 
| Functor (V1 :: Type -> Type) Source # | Since: base-4.9.0.0 | 
| Functor (U1 :: Type -> Type) Source # | Since: base-4.9.0.0 | 
| Functor ((,) a) Source # | Since: base-2.1 | 
| Functor (ST s) Source # | Since: base-2.1 | 
| Functor (Proxy :: Type -> Type) Source # | Since: base-4.7.0.0 | 
| Arrow a => Functor (ArrowMonad a) Source # | Since: base-4.6.0.0 | 
| Defined in Control.Arrow Methods fmap :: (a0 -> b) -> ArrowMonad a a0 -> ArrowMonad a b Source # (<$) :: a0 -> ArrowMonad a b -> ArrowMonad a a0 Source # | |
| Monad m => Functor (WrappedMonad m) Source # | Since: base-2.1 | 
| Defined in Control.Applicative Methods fmap :: (a -> b) -> WrappedMonad m a -> WrappedMonad m b Source # (<$) :: a -> WrappedMonad m b -> WrappedMonad m a Source # | |
| Functor (ST s) Source # | Since: base-2.1 | 
| Functor (Arg a) Source # | Since: base-4.9.0.0 | 
| Functor f => Functor (Rec1 f) Source # | Since: base-4.9.0.0 | 
| Functor (URec Char :: Type -> Type) Source # | Since: base-4.9.0.0 | 
| Functor (URec Double :: Type -> Type) Source # | Since: base-4.9.0.0 | 
| Functor (URec Float :: Type -> Type) Source # | Since: base-4.9.0.0 | 
| Functor (URec Int :: Type -> Type) Source # | Since: base-4.9.0.0 | 
| Functor (URec Word :: Type -> Type) Source # | Since: base-4.9.0.0 | 
| Functor (URec (Ptr ()) :: Type -> Type) Source # | Since: base-4.9.0.0 | 
| Functor f => Functor (Alt f) Source # | Since: base-4.8.0.0 | 
| Functor f => Functor (Ap f) Source # | Since: base-4.12.0.0 | 
| Functor (Const m :: Type -> Type) Source # | Since: base-2.1 | 
| Arrow a => Functor (WrappedArrow a b) Source # | Since: base-2.1 | 
| Defined in Control.Applicative Methods fmap :: (a0 -> b0) -> WrappedArrow a b a0 -> WrappedArrow a b b0 Source # (<$) :: a0 -> WrappedArrow a b b0 -> WrappedArrow a b a0 Source # | |
| Functor ((->) r :: Type -> Type) Source # | Since: base-2.1 | 
| Functor (K1 i c :: Type -> Type) Source # | Since: base-4.9.0.0 | 
| (Functor f, Functor g) => Functor (f :+: g) Source # | Since: base-4.9.0.0 | 
| (Functor f, Functor g) => Functor (f :*: g) Source # | Since: base-4.9.0.0 | 
| (Functor f, Functor g) => Functor (Sum f g) Source # | Since: base-4.9.0.0 | 
| (Functor f, Functor g) => Functor (Product f g) Source # | Since: base-4.9.0.0 | 
| Functor f => Functor (M1 i c f) Source # | Since: base-4.9.0.0 | 
| (Functor f, Functor g) => Functor (f :.: g) Source # | Since: base-4.9.0.0 | 
| (Functor f, Functor g) => Functor (Compose f g) Source # | Since: base-4.9.0.0 | 
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.
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 [] Source # | Since: base-2.1 | 
| Monad Maybe Source # | Since: base-2.1 | 
| Monad IO Source # | Since: base-2.1 | 
| Monad Par1 Source # | Since: base-4.9.0.0 | 
| Monad NonEmpty Source # | Since: base-4.9.0.0 | 
| Monad ReadP Source # | Since: base-2.1 | 
| Monad ReadPrec Source # | Since: base-2.1 | 
| Monad Down Source # | Since: base-4.11.0.0 | 
| Monad Product Source # | Since: base-4.8.0.0 | 
| Monad Sum Source # | Since: base-4.8.0.0 | 
| Monad Dual Source # | Since: base-4.8.0.0 | 
| Monad Last Source # | Since: base-4.8.0.0 | 
| Monad First Source # | Since: base-4.8.0.0 | 
| Monad STM Source # | Since: base-4.3.0.0 | 
| Monad Identity Source # | Since: base-4.8.0.0 | 
| Monad Option Source # | Since: base-4.9.0.0 | 
| Monad Last Source # | Since: base-4.9.0.0 | 
| Monad First Source # | Since: base-4.9.0.0 | 
| Monad Max Source # | Since: base-4.9.0.0 | 
| Monad Min Source # | Since: base-4.9.0.0 | 
| Monad Complex Source # | Since: base-4.9.0.0 | 
| Monad (Either e) Source # | Since: base-4.4.0.0 | 
| Monad (U1 :: Type -> Type) Source # | Since: base-4.9.0.0 | 
| Monoid a => Monad ((,) a) Source # | Since: base-4.9.0.0 | 
| Monad (ST s) Source # | Since: base-2.1 | 
| Monad (Proxy :: Type -> Type) Source # | Since: base-4.7.0.0 | 
| ArrowApply a => Monad (ArrowMonad a) Source # | Since: base-2.1 | 
| Defined in Control.Arrow Methods (>>=) :: ArrowMonad a a0 -> (a0 -> ArrowMonad a b) -> ArrowMonad a b Source # (>>) :: ArrowMonad a a0 -> ArrowMonad a b -> ArrowMonad a b Source # return :: a0 -> ArrowMonad a a0 Source # fail :: String -> ArrowMonad a a0 Source # | |
| Monad m => Monad (WrappedMonad m) Source # | Since: base-4.7.0.0 | 
| Defined in Control.Applicative 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) Source # | Since: base-2.1 | 
| Monad f => Monad (Rec1 f) Source # | Since: base-4.9.0.0 | 
| Monad f => Monad (Alt f) Source # | Since: base-4.8.0.0 | 
| Monad f => Monad (Ap f) Source # | Since: base-4.12.0.0 | 
| Monad ((->) r :: Type -> Type) Source # | Since: base-2.1 | 
| (Monad f, Monad g) => Monad (f :*: g) Source # | Since: base-4.9.0.0 | 
| (Monad f, Monad g) => Monad (Product f g) Source # | Since: base-4.9.0.0 | 
| Monad f => Monad (M1 i c f) Source # | Since: base-4.9.0.0 |