ghc-8.10.7: The GHC API
Safe HaskellSafe-Inferred
LanguageHaskell2010

MonadUtils

Description

Utilities related to Monad and Applicative classes Mostly for backwards compatibility.

Synopsis

Documentation

class Functor f => Applicative (f :: Type -> Type) where Source #

A functor with application, providing operations to

  • embed pure expressions (pure), and
  • sequence computations and combine their results (<*> and liftA2).

A minimal complete definition must include implementations of pure and of either <*> or liftA2. If it defines both, then they must behave the same as their default definitions:

(<*>) = liftA2 id
liftA2 f x y = f <$> x <*> y

Further, any definition must satisfy the following:

Identity
pure id <*> v = v
Composition
pure (.) <*> u <*> v <*> w = u <*> (v <*> w)
Homomorphism
pure f <*> pure x = pure (f x)
Interchange
u <*> pure y = pure ($ y) <*> u

The other methods have the following default definitions, which may be overridden with equivalent specialized implementations:

As a consequence of these laws, the Functor instance for f will satisfy

It may be useful to note that supposing

forall x y. p (q x y) = f x . g y

it follows from the above that

liftA2 p (liftA2 q u v) = liftA2 f u . liftA2 g v

If f is also a Monad, it should satisfy

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

Minimal complete definition

pure, ((<*>) | liftA2)

Methods

pure :: a -> f a Source #

Lift a value.

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

Sequential application.

A few functors support an implementation of <*> that is more efficient than the default one.

Using ApplicativeDo: 'fs <*> as' can be understood as the do expression

do f <- fs
   a <- as
   pure (f a)

liftA2 :: (a -> b -> c) -> f a -> f b -> f c Source #

Lift a binary function to actions.

Some functors support an implementation of liftA2 that is more efficient than the default one. In particular, if fmap is an expensive operation, it is likely better to use liftA2 than to fmap over the structure and then use <*>.

This became a typeclass method in 4.10.0.0. Prior to that, it was a function defined in terms of <*> and fmap.

Using ApplicativeDo: 'liftA2 f as bs' can be understood as the do expression

do a <- as
   b <- bs
   pure (f a b)

(*>) :: f a -> f b -> f b infixl 4 Source #

Sequence actions, discarding the value of the first argument.

'as *> bs' can be understood as the do expression

do as
   bs

This is a tad complicated for our ApplicativeDo extension which will give it a Monad constraint. For an Applicative constraint we write it of the form

do _ <- as
   b <- bs
   pure b

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

Sequence actions, discarding the value of the second argument.

Using ApplicativeDo: 'as <* bs' can be understood as the do expression

do a <- as
   bs
   pure a

Instances

Instances details
Applicative []

Since: base-2.1

Instance details

Defined in GHC.Base

Methods

pure :: a -> [a] Source #

(<*>) :: [a -> b] -> [a] -> [b] Source #

liftA2 :: (a -> b -> c) -> [a] -> [b] -> [c] Source #

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

(<*) :: [a] -> [b] -> [a] Source #

Applicative Maybe

Since: base-2.1

Instance details

Defined in GHC.Base

Methods

pure :: a -> Maybe a Source #

(<*>) :: Maybe (a -> b) -> Maybe a -> Maybe b Source #

liftA2 :: (a -> b -> c) -> Maybe a -> Maybe b -> Maybe c Source #

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

(<*) :: Maybe a -> Maybe b -> Maybe a Source #

Applicative IO

Since: base-2.1

Instance details

Defined in GHC.Base

Methods

pure :: a -> IO a Source #

(<*>) :: IO (a -> b) -> IO a -> IO b Source #

liftA2 :: (a -> b -> c) -> IO a -> IO b -> IO c Source #

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

(<*) :: IO a -> IO b -> IO a Source #

Applicative Par1

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

pure :: a -> Par1 a Source #

(<*>) :: Par1 (a -> b) -> Par1 a -> Par1 b Source #

liftA2 :: (a -> b -> c) -> Par1 a -> Par1 b -> Par1 c Source #

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

(<*) :: Par1 a -> Par1 b -> Par1 a Source #

Applicative Q 
Instance details

Defined in Language.Haskell.TH.Syntax

Methods

pure :: a -> Q a Source #

(<*>) :: Q (a -> b) -> Q a -> Q b Source #

liftA2 :: (a -> b -> c) -> Q a -> Q b -> Q c Source #

(*>) :: Q a -> Q b -> Q b Source #

(<*) :: Q a -> Q b -> Q a Source #

Applicative Complex

Since: base-4.9.0.0

Instance details

Defined in Data.Complex

Methods

pure :: a -> Complex a Source #

(<*>) :: Complex (a -> b) -> Complex a -> Complex b Source #

liftA2 :: (a -> b -> c) -> Complex a -> Complex b -> Complex c Source #

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

(<*) :: Complex a -> Complex b -> Complex a Source #

Applicative Min

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

pure :: a -> Min a Source #

(<*>) :: Min (a -> b) -> Min a -> Min b Source #

liftA2 :: (a -> b -> c) -> Min a -> Min b -> Min c Source #

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

(<*) :: Min a -> Min b -> Min a Source #

Applicative Max

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

pure :: a -> Max a Source #

(<*>) :: Max (a -> b) -> Max a -> Max b Source #

liftA2 :: (a -> b -> c) -> Max a -> Max b -> Max c Source #

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

(<*) :: Max a -> Max b -> Max a Source #

Applicative First

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

pure :: a -> First a Source #

(<*>) :: First (a -> b) -> First a -> First b Source #

liftA2 :: (a -> b -> c) -> First a -> First b -> First c Source #

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

(<*) :: First a -> First b -> First a Source #

Applicative Last

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

pure :: a -> Last a Source #

(<*>) :: Last (a -> b) -> Last a -> Last b Source #

liftA2 :: (a -> b -> c) -> Last a -> Last b -> Last c Source #

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

(<*) :: Last a -> Last b -> Last a Source #

Applicative Option

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

pure :: a -> Option a Source #

(<*>) :: Option (a -> b) -> Option a -> Option b Source #

liftA2 :: (a -> b -> c) -> Option a -> Option b -> Option c Source #

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

(<*) :: Option a -> Option b -> Option a Source #

Applicative ZipList
f <$> ZipList xs1 <*> ... <*> ZipList xsN
    = ZipList (zipWithN f xs1 ... xsN)

where zipWithN refers to the zipWith function of the appropriate arity (zipWith, zipWith3, zipWith4, ...). For example:

(\a b c -> stimes c [a, b]) <$> ZipList "abcd" <*> ZipList "567" <*> ZipList [1..]
    = ZipList (zipWith3 (\a b c -> stimes c [a, b]) "abcd" "567" [1..])
    = ZipList {getZipList = ["a5","b6b6","c7c7c7"]}

Since: base-2.1

Instance details

Defined in Control.Applicative

Methods

pure :: a -> ZipList a Source #

(<*>) :: ZipList (a -> b) -> ZipList a -> ZipList b Source #

liftA2 :: (a -> b -> c) -> ZipList a -> ZipList b -> ZipList c Source #

(*>) :: ZipList a -> ZipList b -> ZipList b Source #

(<*) :: ZipList a -> ZipList b -> ZipList a Source #

Applicative Identity

Since: base-4.8.0.0

Instance details

Defined in Data.Functor.Identity

Methods

pure :: a -> Identity a Source #

(<*>) :: Identity (a -> b) -> Identity a -> Identity b Source #

liftA2 :: (a -> b -> c) -> Identity a -> Identity b -> Identity c Source #

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

(<*) :: Identity a -> Identity b -> Identity a Source #

Applicative STM

Since: base-4.8.0.0

Instance details

Defined in GHC.Conc.Sync

Methods

pure :: a -> STM a Source #

(<*>) :: STM (a -> b) -> STM a -> STM b Source #

liftA2 :: (a -> b -> c) -> STM a -> STM b -> STM c Source #

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

(<*) :: STM a -> STM b -> STM a Source #

Applicative First

Since: base-4.8.0.0

Instance details

Defined in Data.Monoid

Methods

pure :: a -> First a Source #

(<*>) :: First (a -> b) -> First a -> First b Source #

liftA2 :: (a -> b -> c) -> First a -> First b -> First c Source #

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

(<*) :: First a -> First b -> First a Source #

Applicative Last

Since: base-4.8.0.0

Instance details

Defined in Data.Monoid

Methods

pure :: a -> Last a Source #

(<*>) :: Last (a -> b) -> Last a -> Last b Source #

liftA2 :: (a -> b -> c) -> Last a -> Last b -> Last c Source #

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

(<*) :: Last a -> Last b -> Last a Source #

Applicative Dual

Since: base-4.8.0.0

Instance details

Defined in Data.Semigroup.Internal

Methods

pure :: a -> Dual a Source #

(<*>) :: Dual (a -> b) -> Dual a -> Dual b Source #

liftA2 :: (a -> b -> c) -> Dual a -> Dual b -> Dual c Source #

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

(<*) :: Dual a -> Dual b -> Dual a Source #

Applicative Sum

Since: base-4.8.0.0

Instance details

Defined in Data.Semigroup.Internal

Methods

pure :: a -> Sum a Source #

(<*>) :: Sum (a -> b) -> Sum a -> Sum b Source #

liftA2 :: (a -> b -> c) -> Sum a -> Sum b -> Sum c Source #

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

(<*) :: Sum a -> Sum b -> Sum a Source #

Applicative Product

Since: base-4.8.0.0

Instance details

Defined in Data.Semigroup.Internal

Methods

pure :: a -> Product a Source #

(<*>) :: Product (a -> b) -> Product a -> Product b Source #

liftA2 :: (a -> b -> c) -> Product a -> Product b -> Product c Source #

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

(<*) :: Product a -> Product b -> Product a Source #

Applicative Down

Since: base-4.11.0.0

Instance details

Defined in Data.Ord

Methods

pure :: a -> Down a Source #

(<*>) :: Down (a -> b) -> Down a -> Down b Source #

liftA2 :: (a -> b -> c) -> Down a -> Down b -> Down c Source #

(*>) :: Down a -> Down b -> Down b Source #

(<*) :: Down a -> Down b -> Down a Source #

Applicative ReadPrec

Since: base-4.6.0.0

Instance details

Defined in Text.ParserCombinators.ReadPrec

Methods

pure :: a -> ReadPrec a Source #

(<*>) :: ReadPrec (a -> b) -> ReadPrec a -> ReadPrec b Source #

liftA2 :: (a -> b -> c) -> ReadPrec a -> ReadPrec b -> ReadPrec c Source #

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

(<*) :: ReadPrec a -> ReadPrec b -> ReadPrec a Source #

Applicative ReadP

Since: base-4.6.0.0

Instance details

Defined in Text.ParserCombinators.ReadP

Methods

pure :: a -> ReadP a Source #

(<*>) :: ReadP (a -> b) -> ReadP a -> ReadP b Source #

liftA2 :: (a -> b -> c) -> ReadP a -> ReadP b -> ReadP c Source #

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

(<*) :: ReadP a -> ReadP b -> ReadP a Source #

Applicative NonEmpty

Since: base-4.9.0.0

Instance details

Defined in GHC.Base

Methods

pure :: a -> NonEmpty a Source #

(<*>) :: NonEmpty (a -> b) -> NonEmpty a -> NonEmpty b Source #

liftA2 :: (a -> b -> c) -> NonEmpty a -> NonEmpty b -> NonEmpty c Source #

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

(<*) :: NonEmpty a -> NonEmpty b -> NonEmpty a Source #

Applicative PutM 
Instance details

Defined in Data.Binary.Put

Methods

pure :: a -> PutM a Source #

(<*>) :: PutM (a -> b) -> PutM a -> PutM b Source #

liftA2 :: (a -> b -> c) -> PutM a -> PutM b -> PutM c Source #

(*>) :: PutM a -> PutM b -> PutM b Source #

(<*) :: PutM a -> PutM b -> PutM a Source #

Applicative Get 
Instance details

Defined in Data.Binary.Get.Internal

Methods

pure :: a -> Get a Source #

(<*>) :: Get (a -> b) -> Get a -> Get b Source #

liftA2 :: (a -> b -> c) -> Get a -> Get b -> Get c Source #

(*>) :: Get a -> Get b -> Get b Source #

(<*) :: Get a -> Get b -> Get a Source #

Applicative Put 
Instance details

Defined in Data.ByteString.Builder.Internal

Methods

pure :: a -> Put a Source #

(<*>) :: Put (a -> b) -> Put a -> Put b Source #

liftA2 :: (a -> b -> c) -> Put a -> Put b -> Put c Source #

(*>) :: Put a -> Put b -> Put b Source #

(<*) :: Put a -> Put b -> Put a Source #

Applicative Tree 
Instance details

Defined in Data.Tree

Methods

pure :: a -> Tree a Source #

(<*>) :: Tree (a -> b) -> Tree a -> Tree b Source #

liftA2 :: (a -> b -> c) -> Tree a -> Tree b -> Tree c Source #

(*>) :: Tree a -> Tree b -> Tree b Source #

(<*) :: Tree a -> Tree b -> Tree a Source #

Applicative Seq

Since: containers-0.5.4

Instance details

Defined in Data.Sequence.Internal

Methods

pure :: a -> Seq a Source #

(<*>) :: Seq (a -> b) -> Seq a -> Seq b Source #

liftA2 :: (a -> b -> c) -> Seq a -> Seq b -> Seq c Source #

(*>) :: Seq a -> Seq b -> Seq b Source #

(<*) :: Seq a -> Seq b -> Seq a Source #

Applicative Capability 
Instance details

Defined in System.Console.Terminfo.Base

Applicative P

Since: base-4.5.0.0

Instance details

Defined in Text.ParserCombinators.ReadP

Methods

pure :: a -> P a Source #

(<*>) :: P (a -> b) -> P a -> P b Source #

liftA2 :: (a -> b -> c) -> P a -> P b -> P c Source #

(*>) :: P a -> P b -> P b Source #

(<*) :: P a -> P b -> P a Source #

Applicative Pair Source # 
Instance details

Defined in Pair

Methods

pure :: a -> Pair a Source #

(<*>) :: Pair (a -> b) -> Pair a -> Pair b Source #

liftA2 :: (a -> b -> c) -> Pair a -> Pair b -> Pair c Source #

(*>) :: Pair a -> Pair b -> Pair b Source #

(<*) :: Pair a -> Pair b -> Pair a Source #

Applicative UniqSM Source # 
Instance details

Defined in UniqSupply

Methods

pure :: a -> UniqSM a Source #

(<*>) :: UniqSM (a -> b) -> UniqSM a -> UniqSM b Source #

liftA2 :: (a -> b -> c) -> UniqSM a -> UniqSM b -> UniqSM c Source #

(*>) :: UniqSM a -> UniqSM b -> UniqSM b Source #

(<*) :: UniqSM a -> UniqSM b -> UniqSM a Source #

Applicative CoreM Source # 
Instance details

Defined in CoreMonad

Methods

pure :: a -> CoreM a Source #

(<*>) :: CoreM (a -> b) -> CoreM a -> CoreM b Source #

liftA2 :: (a -> b -> c) -> CoreM a -> CoreM b -> CoreM c Source #

(*>) :: CoreM a -> CoreM b -> CoreM b Source #

(<*) :: CoreM a -> CoreM b -> CoreM a Source #

Applicative P Source # 
Instance details

Defined in Lexer

Methods

pure :: a -> P a Source #

(<*>) :: P (a -> b) -> P a -> P b Source #

liftA2 :: (a -> b -> c) -> P a -> P b -> P c Source #

(*>) :: P a -> P b -> P b Source #

(<*) :: P a -> P b -> P a Source #

Applicative PD Source # 
Instance details

Defined in CmmMonad

Methods

pure :: a -> PD a Source #

(<*>) :: PD (a -> b) -> PD a -> PD b Source #

liftA2 :: (a -> b -> c) -> PD a -> PD b -> PD c Source #

(*>) :: PD a -> PD b -> PD b Source #

(<*) :: PD a -> PD b -> PD a Source #

Applicative UnifyResultM Source # 
Instance details

Defined in Unify

Applicative LiftM Source # 
Instance details

Defined in StgLiftLams.LiftM

Methods

pure :: a -> LiftM a Source #

(<*>) :: LiftM (a -> b) -> LiftM a -> LiftM b Source #

liftA2 :: (a -> b -> c) -> LiftM a -> LiftM b -> LiftM c Source #

(*>) :: LiftM a -> LiftM b -> LiftM b Source #

(<*) :: LiftM a -> LiftM b -> LiftM a Source #

Applicative LlvmM Source # 
Instance details

Defined in LlvmCodeGen.Base

Methods

pure :: a -> LlvmM a Source #

(<*>) :: LlvmM (a -> b) -> LlvmM a -> LlvmM b Source #

liftA2 :: (a -> b -> c) -> LlvmM a -> LlvmM b -> LlvmM c Source #

(*>) :: LlvmM a -> LlvmM b -> LlvmM b Source #

(<*) :: LlvmM a -> LlvmM b -> LlvmM a Source #

Applicative FCode Source # 
Instance details

Defined in GHC.StgToCmm.Monad

Methods

pure :: a -> FCode a Source #

(<*>) :: FCode (a -> b) -> FCode a -> FCode b Source #

liftA2 :: (a -> b -> c) -> FCode a -> FCode b -> FCode c Source #

(*>) :: FCode a -> FCode b -> FCode b Source #

(<*) :: FCode a -> FCode b -> FCode a Source #

Applicative CmmParse Source # 
Instance details

Defined in GHC.StgToCmm.ExtCode

Methods

pure :: a -> CmmParse a Source #

(<*>) :: CmmParse (a -> b) -> CmmParse a -> CmmParse b Source #

liftA2 :: (a -> b -> c) -> CmmParse a -> CmmParse b -> CmmParse c Source #

(*>) :: CmmParse a -> CmmParse b -> CmmParse b Source #

(<*) :: CmmParse a -> CmmParse b -> CmmParse a Source #

Applicative PV Source # 
Instance details

Defined in RdrHsSyn

Methods

pure :: a -> PV a Source #

(<*>) :: PV (a -> b) -> PV a -> PV b Source #

liftA2 :: (a -> b -> c) -> PV a -> PV b -> PV c Source #

(*>) :: PV a -> PV b -> PV b Source #

(<*) :: PV a -> PV b -> PV a Source #

Applicative Hsc Source # 
Instance details

Defined in HscTypes

Methods

pure :: a -> Hsc a Source #

(<*>) :: Hsc (a -> b) -> Hsc a -> Hsc b Source #

liftA2 :: (a -> b -> c) -> Hsc a -> Hsc b -> Hsc c Source #

(*>) :: Hsc a -> Hsc b -> Hsc b Source #

(<*) :: Hsc a -> Hsc b -> Hsc a Source #

Applicative CompPipeline Source # 
Instance details

Defined in PipelineMonad

Applicative Ghc Source # 
Instance details

Defined in GhcMonad

Methods

pure :: a -> Ghc a Source #

(<*>) :: Ghc (a -> b) -> Ghc a -> Ghc b Source #

liftA2 :: (a -> b -> c) -> Ghc a -> Ghc b -> Ghc c Source #

(*>) :: Ghc a -> Ghc b -> Ghc b Source #

(<*) :: Ghc a -> Ghc b -> Ghc a Source #

Applicative SimplM Source # 
Instance details

Defined in SimplMonad

Methods

pure :: a -> SimplM a Source #

(<*>) :: SimplM (a -> b) -> SimplM a -> SimplM b Source #

liftA2 :: (a -> b -> c) -> SimplM a -> SimplM b -> SimplM c Source #

(*>) :: SimplM a -> SimplM b -> SimplM b Source #

(<*) :: SimplM a -> SimplM b -> SimplM a Source #

Applicative TcPluginM Source # 
Instance details

Defined in TcRnTypes

Methods

pure :: a -> TcPluginM a Source #

(<*>) :: TcPluginM (a -> b) -> TcPluginM a -> TcPluginM b Source #

liftA2 :: (a -> b -> c) -> TcPluginM a -> TcPluginM b -> TcPluginM c Source #

(*>) :: TcPluginM a -> TcPluginM b -> TcPluginM b Source #

(<*) :: TcPluginM a -> TcPluginM b -> TcPluginM a Source #

Applicative CpsRn Source # 
Instance details

Defined in RnPat

Methods

pure :: a -> CpsRn a Source #

(<*>) :: CpsRn (a -> b) -> CpsRn a -> CpsRn b Source #

liftA2 :: (a -> b -> c) -> CpsRn a -> CpsRn b -> CpsRn c Source #

(*>) :: CpsRn a -> CpsRn b -> CpsRn b Source #

(<*) :: CpsRn a -> CpsRn b -> CpsRn a Source #

Applicative MetaTyVarUpdateResult Source # 
Instance details

Defined in TcUnify

Applicative TcS Source # 
Instance details

Defined in TcSMonad

Methods

pure :: a -> TcS a Source #

(<*>) :: TcS (a -> b) -> TcS a -> TcS b Source #

liftA2 :: (a -> b -> c) -> TcS a -> TcS b -> TcS c Source #

(*>) :: TcS a -> TcS b -> TcS b Source #

(<*) :: TcS a -> TcS b -> TcS a Source #

Applicative NatM Source # 
Instance details

Defined in NCGMonad

Methods

pure :: a -> NatM a Source #

(<*>) :: NatM (a -> b) -> NatM a -> NatM b Source #

liftA2 :: (a -> b -> c) -> NatM a -> NatM b -> NatM c Source #

(*>) :: NatM a -> NatM b -> NatM b Source #

(<*) :: NatM a -> NatM b -> NatM a Source #

Applicative (Either e)

Since: base-3.0

Instance details

Defined in Data.Either

Methods

pure :: a -> Either e a Source #

(<*>) :: Either e (a -> b) -> Either e a -> Either e b Source #

liftA2 :: (a -> b -> c) -> Either e a -> Either e b -> Either e c Source #

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

(<*) :: Either e a -> Either e b -> Either e a Source #

Applicative (U1 :: Type -> Type)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

pure :: a -> U1 a Source #

(<*>) :: U1 (a -> b) -> U1 a -> U1 b Source #

liftA2 :: (a -> b -> c) -> U1 a -> U1 b -> U1 c Source #

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

(<*) :: U1 a -> U1 b -> U1 a Source #

Monoid a => Applicative ((,) a)

For tuples, the Monoid constraint on a determines how the first values merge. For example, Strings concatenate:

("hello ", (+15)) <*> ("world!", 2002)
("hello world!",2017)

Since: base-2.1

Instance details

Defined in GHC.Base

Methods

pure :: a0 -> (a, a0) Source #

(<*>) :: (a, a0 -> b) -> (a, a0) -> (a, b) Source #

liftA2 :: (a0 -> b -> c) -> (a, a0) -> (a, b) -> (a, c) Source #

(*>) :: (a, a0) -> (a, b) -> (a, b) Source #

(<*) :: (a, a0) -> (a, b) -> (a, a0) Source #

Applicative (ST s)

Since: base-4.4.0.0

Instance details

Defined in GHC.ST

Methods

pure :: a -> ST s a Source #

(<*>) :: ST s (a -> b) -> ST s a -> ST s b Source #

liftA2 :: (a -> b -> c) -> ST s a -> ST s b -> ST s c Source #

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

(<*) :: ST s a -> ST s b -> ST s a Source #

Monad m => Applicative (WrappedMonad m)

Since: base-2.1

Instance details

Defined in Control.Applicative

Methods

pure :: a -> WrappedMonad m a Source #

(<*>) :: WrappedMonad m (a -> b) -> WrappedMonad m a -> WrappedMonad m b Source #

liftA2 :: (a -> b -> c) -> WrappedMonad m a -> WrappedMonad m b -> WrappedMonad m c Source #

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

(<*) :: WrappedMonad m a -> WrappedMonad m b -> WrappedMonad m a Source #

Arrow a => Applicative (ArrowMonad a)

Since: base-4.6.0.0

Instance details

Defined in Control.Arrow

Methods

pure :: a0 -> ArrowMonad a a0 Source #

(<*>) :: ArrowMonad a (a0 -> b) -> ArrowMonad a a0 -> ArrowMonad a b Source #

liftA2 :: (a0 -> b -> c) -> ArrowMonad a a0 -> ArrowMonad a b -> ArrowMonad a c Source #

(*>) :: ArrowMonad a a0 -> ArrowMonad a b -> ArrowMonad a b Source #

(<*) :: ArrowMonad a a0 -> ArrowMonad a b -> ArrowMonad a a0 Source #

Applicative (Proxy :: Type -> Type)

Since: base-4.7.0.0

Instance details

Defined in Data.Proxy

Methods

pure :: a -> Proxy a Source #

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

liftA2 :: (a -> b -> c) -> Proxy a -> Proxy b -> Proxy c Source #

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

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

(Functor m, Monad m) => Applicative (MaybeT m) 
Instance details

Defined in Control.Monad.Trans.Maybe

Methods

pure :: a -> MaybeT m a Source #

(<*>) :: MaybeT m (a -> b) -> MaybeT m a -> MaybeT m b Source #

liftA2 :: (a -> b -> c) -> MaybeT m a -> MaybeT m b -> MaybeT m c Source #

(*>) :: MaybeT m a -> MaybeT m b -> MaybeT m b Source #

(<*) :: MaybeT m a -> MaybeT m b -> MaybeT m a Source #

Applicative (State s) Source # 
Instance details

Defined in State

Methods

pure :: a -> State s a Source #

(<*>) :: State s (a -> b) -> State s a -> State s b Source #

liftA2 :: (a -> b -> c) -> State s a -> State s b -> State s c Source #

(*>) :: State s a -> State s b -> State s b Source #

(<*) :: State s a -> State s b -> State s a Source #

Applicative (MaybeErr err) Source # 
Instance details

Defined in Maybes

Methods

pure :: a -> MaybeErr err a Source #

(<*>) :: MaybeErr err (a -> b) -> MaybeErr err a -> MaybeErr err b Source #

liftA2 :: (a -> b -> c) -> MaybeErr err a -> MaybeErr err b -> MaybeErr err c Source #

(*>) :: MaybeErr err a -> MaybeErr err b -> MaybeErr err b Source #

(<*) :: MaybeErr err a -> MaybeErr err b -> MaybeErr err a Source #

Applicative (SetM s) 
Instance details

Defined in Data.Graph

Methods

pure :: a -> SetM s a Source #

(<*>) :: SetM s (a -> b) -> SetM s a -> SetM s b Source #

liftA2 :: (a -> b -> c) -> SetM s a -> SetM s b -> SetM s c Source #

(*>) :: SetM s a -> SetM s b -> SetM s b Source #

(<*) :: SetM s a -> SetM s b -> SetM s a Source #

Applicative (CmdLineP s) Source # 
Instance details

Defined in CmdLineParser

Methods

pure :: a -> CmdLineP s a Source #

(<*>) :: CmdLineP s (a -> b) -> CmdLineP s a -> CmdLineP s b Source #

liftA2 :: (a -> b -> c) -> CmdLineP s a -> CmdLineP s b -> CmdLineP s c Source #

(*>) :: CmdLineP s a -> CmdLineP s b -> CmdLineP s b Source #

(<*) :: CmdLineP s a -> CmdLineP s b -> CmdLineP s a Source #

Monad m => Applicative (EwM m) Source # 
Instance details

Defined in CmdLineParser

Methods

pure :: a -> EwM m a Source #

(<*>) :: EwM m (a -> b) -> EwM m a -> EwM m b Source #

liftA2 :: (a -> b -> c) -> EwM m a -> EwM m b -> EwM m c Source #

(*>) :: EwM m a -> EwM m b -> EwM m b Source #

(<*) :: EwM m a -> EwM m b -> EwM m a Source #

Applicative (IOEnv m) Source # 
Instance details

Defined in IOEnv

Methods

pure :: a -> IOEnv m a Source #

(<*>) :: IOEnv m (a -> b) -> IOEnv m a -> IOEnv m b Source #

liftA2 :: (a -> b -> c) -> IOEnv m a -> IOEnv m b -> IOEnv m c Source #

(*>) :: IOEnv m a -> IOEnv m b -> IOEnv m b Source #

(<*) :: IOEnv m a -> IOEnv m b -> IOEnv m a Source #

Applicative (RegM freeRegs) Source # 
Instance details

Defined in RegAlloc.Linear.State

Methods

pure :: a -> RegM freeRegs a Source #

(<*>) :: RegM freeRegs (a -> b) -> RegM freeRegs a -> RegM freeRegs b Source #

liftA2 :: (a -> b -> c) -> RegM freeRegs a -> RegM freeRegs b -> RegM freeRegs c Source #

(*>) :: RegM freeRegs a -> RegM freeRegs b -> RegM freeRegs b Source #

(<*) :: RegM freeRegs a -> RegM freeRegs b -> RegM freeRegs a Source #

Applicative m => Applicative (GhcT m) Source # 
Instance details

Defined in GhcMonad

Methods

pure :: a -> GhcT m a Source #

(<*>) :: GhcT m (a -> b) -> GhcT m a -> GhcT m b Source #

liftA2 :: (a -> b -> c) -> GhcT m a -> GhcT m b -> GhcT m c Source #

(*>) :: GhcT m a -> GhcT m b -> GhcT m b Source #

(<*) :: GhcT m a -> GhcT m b -> GhcT m a Source #

Applicative f => Applicative (Rec1 f)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

pure :: a -> Rec1 f a Source #

(<*>) :: Rec1 f (a -> b) -> Rec1 f a -> Rec1 f b Source #

liftA2 :: (a -> b -> c) -> Rec1 f a -> Rec1 f b -> Rec1 f c Source #

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

(<*) :: Rec1 f a -> Rec1 f b -> Rec1 f a Source #

(Monoid a, Monoid b) => Applicative ((,,) a b)

Since: base-4.14.0.0

Instance details

Defined in GHC.Base

Methods

pure :: a0 -> (a, b, a0) Source #

(<*>) :: (a, b, a0 -> b0) -> (a, b, a0) -> (a, b, b0) Source #

liftA2 :: (a0 -> b0 -> c) -> (a, b, a0) -> (a, b, b0) -> (a, b, c) Source #

(*>) :: (a, b, a0) -> (a, b, b0) -> (a, b, b0) Source #

(<*) :: (a, b, a0) -> (a, b, b0) -> (a, b, a0) Source #

Arrow a => Applicative (WrappedArrow a b)

Since: base-2.1

Instance details

Defined in Control.Applicative

Methods

pure :: a0 -> WrappedArrow a b a0 Source #

(<*>) :: WrappedArrow a b (a0 -> b0) -> WrappedArrow a b a0 -> WrappedArrow a b b0 Source #

liftA2 :: (a0 -> b0 -> c) -> WrappedArrow a b a0 -> WrappedArrow a b b0 -> WrappedArrow a b c Source #

(*>) :: WrappedArrow a b a0 -> WrappedArrow a b b0 -> WrappedArrow a b b0 Source #

(<*) :: WrappedArrow a b a0 -> WrappedArrow a b b0 -> WrappedArrow a b a0 Source #

Applicative m => Applicative (Kleisli m a)

Since: base-4.14.0.0

Instance details

Defined in Control.Arrow

Methods

pure :: a0 -> Kleisli m a a0 Source #

(<*>) :: Kleisli m a (a0 -> b) -> Kleisli m a a0 -> Kleisli m a b Source #

liftA2 :: (a0 -> b -> c) -> Kleisli m a a0 -> Kleisli m a b -> Kleisli m a c Source #

(*>) :: Kleisli m a a0 -> Kleisli m a b -> Kleisli m a b Source #

(<*) :: Kleisli m a a0 -> Kleisli m a b -> Kleisli m a a0 Source #

Monoid m => Applicative (Const m :: Type -> Type)

Since: base-2.0.1

Instance details

Defined in Data.Functor.Const

Methods

pure :: a -> Const m a Source #

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

liftA2 :: (a -> b -> c) -> Const m a -> Const m b -> Const m c Source #

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

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

Applicative f => Applicative (Ap f)

Since: base-4.12.0.0

Instance details

Defined in Data.Monoid

Methods

pure :: a -> Ap f a Source #

(<*>) :: Ap f (a -> b) -> Ap f a -> Ap f b Source #

liftA2 :: (a -> b -> c) -> Ap f a -> Ap f b -> Ap f c Source #

(*>) :: Ap f a -> Ap f b -> Ap f b Source #

(<*) :: Ap f a -> Ap f b -> Ap f a Source #

Applicative f => Applicative (Alt f)

Since: base-4.8.0.0

Instance details

Defined in Data.Semigroup.Internal

Methods

pure :: a -> Alt f a Source #

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

liftA2 :: (a -> b -> c) -> Alt f a -> Alt f b -> Alt f c Source #

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

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

(Applicative f, Monad f) => Applicative (WhenMissing f x)

Equivalent to ReaderT k (ReaderT x (MaybeT f)).

Since: containers-0.5.9

Instance details

Defined in Data.IntMap.Internal

Methods

pure :: a -> WhenMissing f x a Source #

(<*>) :: WhenMissing f x (a -> b) -> WhenMissing f x a -> WhenMissing f x b Source #

liftA2 :: (a -> b -> c) -> WhenMissing f x a -> WhenMissing f x b -> WhenMissing f x c Source #

(*>) :: WhenMissing f x a -> WhenMissing f x b -> WhenMissing f x b Source #

(<*) :: WhenMissing f x a -> WhenMissing f x b -> WhenMissing f x a Source #

(Monoid w, Applicative m) => Applicative (WriterT w m) 
Instance details

Defined in Control.Monad.Trans.Writer.Lazy

Methods

pure :: a -> WriterT w m a Source #

(<*>) :: WriterT w m (a -> b) -> WriterT w m a -> WriterT w m b Source #

liftA2 :: (a -> b -> c) -> WriterT w m a -> WriterT w m b -> WriterT w m c Source #

(*>) :: WriterT w m a -> WriterT w m b -> WriterT w m b Source #

(<*) :: WriterT w m a -> WriterT w m b -> WriterT w m a Source #

(Functor m, Monad m) => Applicative (StateT s m) 
Instance details

Defined in Control.Monad.Trans.State.Strict

Methods

pure :: a -> StateT s m a Source #

(<*>) :: StateT s m (a -> b) -> StateT s m a -> StateT s m b Source #

liftA2 :: (a -> b -> c) -> StateT s m a -> StateT s m b -> StateT s m c Source #

(*>) :: StateT s m a -> StateT s m b -> StateT s m b Source #

(<*) :: StateT s m a -> StateT s m b -> StateT s m a Source #

(Functor m, Monad m) => Applicative (StateT s m) 
Instance details

Defined in Control.Monad.Trans.State.Lazy

Methods

pure :: a -> StateT s m a Source #

(<*>) :: StateT s m (a -> b) -> StateT s m a -> StateT s m b Source #

liftA2 :: (a -> b -> c) -> StateT s m a -> StateT s m b -> StateT s m c Source #

(*>) :: StateT s m a -> StateT s m b -> StateT s m b Source #

(<*) :: StateT s m a -> StateT s m b -> StateT s m a Source #

Applicative m => Applicative (ReaderT r m) 
Instance details

Defined in Control.Monad.Trans.Reader

Methods

pure :: a -> ReaderT r m a Source #

(<*>) :: ReaderT r m (a -> b) -> ReaderT r m a -> ReaderT r m b Source #

liftA2 :: (a -> b -> c) -> ReaderT r m a -> ReaderT r m b -> ReaderT r m c Source #

(*>) :: ReaderT r m a -> ReaderT r m b -> ReaderT r m b Source #

(<*) :: ReaderT r m a -> ReaderT r m b -> ReaderT r m a Source #

(Functor m, Monad m) => Applicative (ExceptT e m) 
Instance details

Defined in Control.Monad.Trans.Except

Methods

pure :: a -> ExceptT e m a Source #

(<*>) :: ExceptT e m (a -> b) -> ExceptT e m a -> ExceptT e m b Source #

liftA2 :: (a -> b -> c) -> ExceptT e m a -> ExceptT e m b -> ExceptT e m c Source #

(*>) :: ExceptT e m a -> ExceptT e m b -> ExceptT e m b Source #

(<*) :: ExceptT e m a -> ExceptT e m b -> ExceptT e m a Source #

Monad m => Applicative (Stream m a) Source # 
Instance details

Defined in Stream

Methods

pure :: a0 -> Stream m a a0 Source #

(<*>) :: Stream m a (a0 -> b) -> Stream m a a0 -> Stream m a b Source #

liftA2 :: (a0 -> b -> c) -> Stream m a a0 -> Stream m a b -> Stream m a c Source #

(*>) :: Stream m a a0 -> Stream m a b -> Stream m a b Source #

(<*) :: Stream m a a0 -> Stream m a b -> Stream m a a0 Source #

Applicative ((->) r :: Type -> Type)

Since: base-2.1

Instance details

Defined in GHC.Base

Methods

pure :: a -> r -> a Source #

(<*>) :: (r -> (a -> b)) -> (r -> a) -> r -> b Source #

liftA2 :: (a -> b -> c) -> (r -> a) -> (r -> b) -> r -> c Source #

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

(<*) :: (r -> a) -> (r -> b) -> r -> a Source #

Monoid c => Applicative (K1 i c :: Type -> Type)

Since: base-4.12.0.0

Instance details

Defined in GHC.Generics

Methods

pure :: a -> K1 i c a Source #

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

liftA2 :: (a -> b -> c0) -> K1 i c a -> K1 i c b -> K1 i c c0 Source #

(*>) :: K1 i c a -> K1 i c b -> K1 i c b Source #

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

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

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

pure :: a -> (f :*: g) a Source #

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

liftA2 :: (a -> b -> c) -> (f :*: g) a -> (f :*: g) b -> (f :*: g) c Source #

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

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

(Monoid a, Monoid b, Monoid c) => Applicative ((,,,) a b c)

Since: base-4.14.0.0

Instance details

Defined in GHC.Base

Methods

pure :: a0 -> (a, b, c, a0) Source #

(<*>) :: (a, b, c, a0 -> b0) -> (a, b, c, a0) -> (a, b, c, b0) Source #

liftA2 :: (a0 -> b0 -> c0) -> (a, b, c, a0) -> (a, b, c, b0) -> (a, b, c, c0) Source #

(*>) :: (a, b, c, a0) -> (a, b, c, b0) -> (a, b, c, b0) Source #

(<*) :: (a, b, c, a0) -> (a, b, c, b0) -> (a, b, c, a0) Source #

(Applicative f, Applicative g) => Applicative (Product f g)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Product

Methods

pure :: a -> Product f g a Source #

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

liftA2 :: (a -> b -> c) -> Product f g a -> Product f g b -> Product f g c Source #

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

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

(Monad f, Applicative f) => Applicative (WhenMatched f x y)

Equivalent to ReaderT Key (ReaderT x (ReaderT y (MaybeT f)))

Since: containers-0.5.9

Instance details

Defined in Data.IntMap.Internal

Methods

pure :: a -> WhenMatched f x y a Source #

(<*>) :: WhenMatched f x y (a -> b) -> WhenMatched f x y a -> WhenMatched f x y b Source #

liftA2 :: (a -> b -> c) -> WhenMatched f x y a -> WhenMatched f x y b -> WhenMatched f x y c Source #

(*>) :: WhenMatched f x y a -> WhenMatched f x y b -> WhenMatched f x y b Source #

(<*) :: WhenMatched f x y a -> WhenMatched f x y b -> WhenMatched f x y a Source #

(Applicative f, Monad f) => Applicative (WhenMissing f k x)

Equivalent to ReaderT k (ReaderT x (MaybeT f)) .

Since: containers-0.5.9

Instance details

Defined in Data.Map.Internal

Methods

pure :: a -> WhenMissing f k x a Source #

(<*>) :: WhenMissing f k x (a -> b) -> WhenMissing f k x a -> WhenMissing f k x b Source #

liftA2 :: (a -> b -> c) -> WhenMissing f k x a -> WhenMissing f k x b -> WhenMissing f k x c Source #

(*>) :: WhenMissing f k x a -> WhenMissing f k x b -> WhenMissing f k x b Source #

(<*) :: WhenMissing f k x a -> WhenMissing f k x b -> WhenMissing f k x a Source #

Applicative (ContT r m) 
Instance details

Defined in Control.Monad.Trans.Cont

Methods

pure :: a -> ContT r m a Source #

(<*>) :: ContT r m (a -> b) -> ContT r m a -> ContT r m b Source #

liftA2 :: (a -> b -> c) -> ContT r m a -> ContT r m b -> ContT r m c Source #

(*>) :: ContT r m a -> ContT r m b -> ContT r m b Source #

(<*) :: ContT r m a -> ContT r m b -> ContT r m a Source #

Applicative f => Applicative (M1 i c f)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

pure :: a -> M1 i c f a Source #

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

liftA2 :: (a -> b -> c0) -> M1 i c f a -> M1 i c f b -> M1 i c f c0 Source #

(*>) :: M1 i c f 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 a Source #

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

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Methods

pure :: a -> (f :.: g) a Source #

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

liftA2 :: (a -> b -> c) -> (f :.: g) a -> (f :.: g) b -> (f :.: g) c Source #

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

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

(Applicative f, Applicative g) => Applicative (Compose f g)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Compose

Methods

pure :: a -> Compose f g a Source #

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

liftA2 :: (a -> b -> c) -> Compose f g a -> Compose f g b -> Compose f g c Source #

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

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

(Monad f, Applicative f) => Applicative (WhenMatched f k x y)

Equivalent to ReaderT k (ReaderT x (ReaderT y (MaybeT f)))

Since: containers-0.5.9

Instance details

Defined in Data.Map.Internal

Methods

pure :: a -> WhenMatched f k x y a Source #

(<*>) :: WhenMatched f k x y (a -> b) -> WhenMatched f k x y a -> WhenMatched f k x y b Source #

liftA2 :: (a -> b -> c) -> WhenMatched f k x y a -> WhenMatched f k x y b -> WhenMatched f k x y c Source #

(*>) :: WhenMatched f k x y a -> WhenMatched f k x y b -> WhenMatched f k x y b Source #

(<*) :: WhenMatched f k x y a -> WhenMatched f k x y b -> WhenMatched f k x y a Source #

(Monoid w, Functor m, Monad m) => Applicative (RWST r w s m) 
Instance details

Defined in Control.Monad.Trans.RWS.Strict

Methods

pure :: a -> RWST r w s m a Source #

(<*>) :: RWST r w s m (a -> b) -> RWST r w s m a -> RWST r w s m b Source #

liftA2 :: (a -> b -> c) -> RWST r w s m a -> RWST r w s m b -> RWST r w s m c Source #

(*>) :: RWST r w s m a -> RWST r w s m b -> RWST r w s m b Source #

(<*) :: RWST r w s m a -> RWST r w s m b -> RWST r w s m a Source #

(Functor m, Monad m) => Applicative (RWST r w s m) 
Instance details

Defined in Control.Monad.Trans.RWS.CPS

Methods

pure :: a -> RWST r w s m a Source #

(<*>) :: RWST r w s m (a -> b) -> RWST r w s m a -> RWST r w s m b Source #

liftA2 :: (a -> b -> c) -> RWST r w s m a -> RWST r w s m b -> RWST r w s m c Source #

(*>) :: RWST r w s m a -> RWST r w s m b -> RWST r w s m b Source #

(<*) :: RWST r w s m a -> RWST r w s m b -> RWST r w s m a Source #

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

An infix synonym for fmap.

The name of this operator is an allusion to $. Note the similarities between their types:

 ($)  ::              (a -> b) ->   a ->   b
(<$>) :: Functor f => (a -> b) -> f a -> f b

Whereas $ is function application, <$> is function application lifted over a Functor.

Examples

Expand

Convert from a Maybe Int to a Maybe String using show:

>>> show <$> Nothing
Nothing
>>> show <$> Just 3
Just "3"

Convert from an Either Int Int to an Either Int String using show:

>>> show <$> Left 17
Left 17
>>> show <$> Right 17
Right "17"

Double each element of a list:

>>> (*2) <$> [1,2,3]
[2,4,6]

Apply even to the second element of a pair:

>>> even <$> (2,2)
(2,True)

class Monad m => MonadFix (m :: Type -> Type) where Source #

Monads having fixed points with a 'knot-tying' semantics. Instances of MonadFix should satisfy the following laws:

Purity
mfix (return . h) = return (fix h)
Left shrinking (or Tightening)
mfix (\x -> a >>= \y -> f x y) = a >>= \y -> mfix (\x -> f x y)
Sliding
mfix (liftM h . f) = liftM h (mfix (f . h)), for strict h.
Nesting
mfix (\x -> mfix (\y -> f x y)) = mfix (\x -> f x x)

This class is used in the translation of the recursive do notation supported by GHC and Hugs.

Methods

mfix :: (a -> m a) -> m a Source #

The fixed point of a monadic computation. mfix f executes the action f only once, with the eventual output fed back as the input. Hence f should not be strict, for then mfix f would diverge.

Instances

Instances details
MonadFix []

Since: base-2.1

Instance details

Defined in Control.Monad.Fix

Methods

mfix :: (a -> [a]) -> [a] Source #

MonadFix Maybe

Since: base-2.1

Instance details

Defined in Control.Monad.Fix

Methods

mfix :: (a -> Maybe a) -> Maybe a Source #

MonadFix IO

Since: base-2.1

Instance details

Defined in Control.Monad.Fix

Methods

mfix :: (a -> IO a) -> IO a Source #

MonadFix Par1

Since: base-4.9.0.0

Instance details

Defined in Control.Monad.Fix

Methods

mfix :: (a -> Par1 a) -> Par1 a Source #

MonadFix Min

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

mfix :: (a -> Min a) -> Min a Source #

MonadFix Max

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

mfix :: (a -> Max a) -> Max a Source #

MonadFix First

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

mfix :: (a -> First a) -> First a Source #

MonadFix Last

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

mfix :: (a -> Last a) -> Last a Source #

MonadFix Option

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup

Methods

mfix :: (a -> Option a) -> Option a Source #

MonadFix Identity

Since: base-4.8.0.0

Instance details

Defined in Data.Functor.Identity

Methods

mfix :: (a -> Identity a) -> Identity a Source #

MonadFix First

Since: base-4.8.0.0

Instance details

Defined in Control.Monad.Fix

Methods

mfix :: (a -> First a) -> First a Source #

MonadFix Last

Since: base-4.8.0.0

Instance details

Defined in Control.Monad.Fix

Methods

mfix :: (a -> Last a) -> Last a Source #

MonadFix Dual

Since: base-4.8.0.0

Instance details

Defined in Control.Monad.Fix

Methods

mfix :: (a -> Dual a) -> Dual a Source #

MonadFix Sum

Since: base-4.8.0.0

Instance details

Defined in Control.Monad.Fix

Methods

mfix :: (a -> Sum a) -> Sum a Source #

MonadFix Product

Since: base-4.8.0.0

Instance details

Defined in Control.Monad.Fix

Methods

mfix :: (a -> Product a) -> Product a Source #

MonadFix Down

Since: base-4.12.0.0

Instance details

Defined in Control.Monad.Fix

Methods

mfix :: (a -> Down a) -> Down a Source #

MonadFix NonEmpty

Since: base-4.9.0.0

Instance details

Defined in Control.Monad.Fix

Methods

mfix :: (a -> NonEmpty a) -> NonEmpty a Source #

MonadFix Tree

Since: containers-0.5.11

Instance details

Defined in Data.Tree

Methods

mfix :: (a -> Tree a) -> Tree a Source #

MonadFix Seq

Since: containers-0.5.11

Instance details

Defined in Data.Sequence.Internal

Methods

mfix :: (a -> Seq a) -> Seq a Source #

MonadFix UniqSM Source # 
Instance details

Defined in UniqSupply

Methods

mfix :: (a -> UniqSM a) -> UniqSM a Source #

MonadFix Ghc Source # 
Instance details

Defined in GhcMonad

Methods

mfix :: (a -> Ghc a) -> Ghc a Source #

MonadFix (Either e)

Since: base-4.3.0.0

Instance details

Defined in Control.Monad.Fix

Methods

mfix :: (a -> Either e a) -> Either e a Source #

MonadFix (ST s)

Since: base-2.1

Instance details

Defined in Control.Monad.Fix

Methods

mfix :: (a -> ST s a) -> ST s a Source #

MonadFix m => MonadFix (MaybeT m) 
Instance details

Defined in Control.Monad.Trans.Maybe

Methods

mfix :: (a -> MaybeT m a) -> MaybeT m a Source #

MonadFix f => MonadFix (Rec1 f)

Since: base-4.9.0.0

Instance details

Defined in Control.Monad.Fix

Methods

mfix :: (a -> Rec1 f a) -> Rec1 f a Source #

MonadFix f => MonadFix (Ap f)

Since: base-4.12.0.0

Instance details

Defined in Control.Monad.Fix

Methods

mfix :: (a -> Ap f a) -> Ap f a Source #

MonadFix f => MonadFix (Alt f)

Since: base-4.8.0.0

Instance details

Defined in Control.Monad.Fix

Methods

mfix :: (a -> Alt f a) -> Alt f a Source #

(Monoid w, MonadFix m) => MonadFix (WriterT w m) 
Instance details

Defined in Control.Monad.Trans.Writer.Lazy

Methods

mfix :: (a -> WriterT w m a) -> WriterT w m a Source #

MonadFix m => MonadFix (StateT s m) 
Instance details

Defined in Control.Monad.Trans.State.Strict

Methods

mfix :: (a -> StateT s m a) -> StateT s m a Source #

MonadFix m => MonadFix (StateT s m) 
Instance details

Defined in Control.Monad.Trans.State.Lazy

Methods

mfix :: (a -> StateT s m a) -> StateT s m a Source #

MonadFix m => MonadFix (ReaderT r m) 
Instance details

Defined in Control.Monad.Trans.Reader

Methods

mfix :: (a -> ReaderT r m a) -> ReaderT r m a Source #

MonadFix m => MonadFix (ExceptT e m) 
Instance details

Defined in Control.Monad.Trans.Except

Methods

mfix :: (a -> ExceptT e m a) -> ExceptT e m a Source #

MonadFix ((->) r :: Type -> Type)

Since: base-2.1

Instance details

Defined in Control.Monad.Fix

Methods

mfix :: (a -> r -> a) -> r -> a Source #

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

Since: base-4.9.0.0

Instance details

Defined in Control.Monad.Fix

Methods

mfix :: (a -> (f :*: g) a) -> (f :*: g) a Source #

(MonadFix f, MonadFix g) => MonadFix (Product f g)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Product

Methods

mfix :: (a -> Product f g a) -> Product f g a Source #

MonadFix f => MonadFix (M1 i c f)

Since: base-4.9.0.0

Instance details

Defined in Control.Monad.Fix

Methods

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

(Monoid w, MonadFix m) => MonadFix (RWST r w s m) 
Instance details

Defined in Control.Monad.Trans.RWS.Strict

Methods

mfix :: (a -> RWST r w s m a) -> RWST r w s m a Source #

MonadFix m => MonadFix (RWST r w s m) 
Instance details

Defined in Control.Monad.Trans.RWS.CPS

Methods

mfix :: (a -> RWST r w s m a) -> RWST r w s m a Source #

class Monad m => MonadIO (m :: Type -> Type) where Source #

Monads in which IO computations may be embedded. Any monad built by applying a sequence of monad transformers to the IO monad will be an instance of this class.

Instances should satisfy the following laws, which state that liftIO is a transformer of monads:

Methods

liftIO :: IO a -> m a Source #

Lift a computation from the IO monad.

Instances

Instances details
MonadIO IO

Since: base-4.9.0.0

Instance details

Defined in Control.Monad.IO.Class

Methods

liftIO :: IO a -> IO a Source #

MonadIO Q 
Instance details

Defined in Language.Haskell.TH.Syntax

Methods

liftIO :: IO a -> Q a Source #

MonadIO CoreM Source # 
Instance details

Defined in CoreMonad

Methods

liftIO :: IO a -> CoreM a Source #

MonadIO Hsc Source # 
Instance details

Defined in HscTypes

Methods

liftIO :: IO a -> Hsc a Source #

MonadIO CompPipeline Source # 
Instance details

Defined in PipelineMonad

Methods

liftIO :: IO a -> CompPipeline a Source #

MonadIO Ghc Source # 
Instance details

Defined in GhcMonad

Methods

liftIO :: IO a -> Ghc a Source #

MonadIO SimplM Source # 
Instance details

Defined in SimplMonad

Methods

liftIO :: IO a -> SimplM a Source #

MonadIO m => MonadIO (MaybeT m) 
Instance details

Defined in Control.Monad.Trans.Maybe

Methods

liftIO :: IO a -> MaybeT m a Source #

MonadIO (IOEnv env) Source # 
Instance details

Defined in IOEnv

Methods

liftIO :: IO a -> IOEnv env a Source #

MonadIO m => MonadIO (GhcT m) Source # 
Instance details

Defined in GhcMonad

Methods

liftIO :: IO a -> GhcT m a Source #

(Monoid w, MonadIO m) => MonadIO (WriterT w m) 
Instance details

Defined in Control.Monad.Trans.Writer.Lazy

Methods

liftIO :: IO a -> WriterT w m a Source #

MonadIO m => MonadIO (StateT s m) 
Instance details

Defined in Control.Monad.Trans.State.Strict

Methods

liftIO :: IO a -> StateT s m a Source #

MonadIO m => MonadIO (StateT s m) 
Instance details

Defined in Control.Monad.Trans.State.Lazy

Methods

liftIO :: IO a -> StateT s m a Source #

MonadIO m => MonadIO (ReaderT r m) 
Instance details

Defined in Control.Monad.Trans.Reader

Methods

liftIO :: IO a -> ReaderT r m a Source #

MonadIO m => MonadIO (ExceptT e m) 
Instance details

Defined in Control.Monad.Trans.Except

Methods

liftIO :: IO a -> ExceptT e m a Source #

MonadIO m => MonadIO (ContT r m) 
Instance details

Defined in Control.Monad.Trans.Cont

Methods

liftIO :: IO a -> ContT r m a Source #

(Monoid w, MonadIO m) => MonadIO (RWST r w s m) 
Instance details

Defined in Control.Monad.Trans.RWS.Strict

Methods

liftIO :: IO a -> RWST r w s m a Source #

MonadIO m => MonadIO (RWST r w s m) 
Instance details

Defined in Control.Monad.Trans.RWS.CPS

Methods

liftIO :: IO a -> RWST r w s m a Source #

zipWith3M :: Monad m => (a -> b -> c -> m d) -> [a] -> [b] -> [c] -> m [d] Source #

zipWith3M_ :: Monad m => (a -> b -> c -> m d) -> [a] -> [b] -> [c] -> m () Source #

zipWith4M :: Monad m => (a -> b -> c -> d -> m e) -> [a] -> [b] -> [c] -> [d] -> m [e] Source #

zipWithAndUnzipM :: Monad m => (a -> b -> m (c, d)) -> [a] -> [b] -> m ([c], [d]) Source #

mapAndUnzipM :: Applicative m => (a -> m (b, c)) -> [a] -> m ([b], [c]) Source #

The mapAndUnzipM function maps its first argument over a list, returning the result as a pair of lists. This function is mainly used with complicated data structures or a state monad.

mapAndUnzip3M :: Monad m => (a -> m (b, c, d)) -> [a] -> m ([b], [c], [d]) Source #

mapAndUnzipM for triples

mapAndUnzip4M :: Monad m => (a -> m (b, c, d, e)) -> [a] -> m ([b], [c], [d], [e]) Source #

mapAndUnzip5M :: Monad m => (a -> m (b, c, d, e, f)) -> [a] -> m ([b], [c], [d], [e], [f]) Source #

mapAccumLM Source #

Arguments

:: Monad m 
=> (acc -> x -> m (acc, y))

combining function

-> acc

initial state

-> [x]

inputs

-> m (acc, [y])

final state, outputs

Monadic version of mapAccumL

mapSndM :: Monad m => (b -> m c) -> [(a, b)] -> m [(a, c)] Source #

Monadic version of mapSnd

concatMapM :: Monad m => (a -> m [b]) -> [a] -> m [b] Source #

Monadic version of concatMap

mapMaybeM :: Applicative m => (a -> m (Maybe b)) -> [a] -> m [b] Source #

Applicative version of mapMaybe

fmapMaybeM :: Monad m => (a -> m b) -> Maybe a -> m (Maybe b) Source #

Monadic version of fmap

fmapEitherM :: Monad m => (a -> m b) -> (c -> m d) -> Either a c -> m (Either b d) Source #

Monadic version of fmap

anyM :: Monad m => (a -> m Bool) -> [a] -> m Bool Source #

Monadic version of any, aborts the computation at the first True value

allM :: Monad m => (a -> m Bool) -> [a] -> m Bool Source #

Monad version of all, aborts the computation at the first False value

orM :: Monad m => m Bool -> m Bool -> m Bool Source #

Monadic version of or

foldlM :: (Foldable t, Monad m) => (b -> a -> m b) -> b -> t a -> m b Source #

Monadic fold over the elements of a structure, associating to the left, i.e. from left to right.

foldlM_ :: (Monad m, Foldable t) => (a -> b -> m a) -> a -> t b -> m () Source #

Monadic version of foldl that discards its result

foldrM :: (Foldable t, Monad m) => (a -> b -> m b) -> b -> t a -> m b Source #

Monadic fold over the elements of a structure, associating to the right, i.e. from right to left.

maybeMapM :: Monad m => (a -> m b) -> Maybe a -> m (Maybe b) Source #

Monadic version of fmap specialised for Maybe

whenM :: Monad m => m Bool -> m () -> m () Source #

Monadic version of when, taking the condition in the monad

unlessM :: Monad m => m Bool -> m () -> m () Source #

Monadic version of unless, taking the condition in the monad

filterOutM :: Applicative m => (a -> m Bool) -> [a] -> m [a] Source #

Like filterM, only it reverses the sense of the test.