MonadUtils

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

Documentation

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

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:

• u *> v = (id <$ u) <*> v

• u <* v = liftA2 const u v

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

• fmap f x = pure f <*> x

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

• pure = return

• (<*>) = ap

• (*>) = (>>)

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

Minimal complete definition

pure, ((<*>) | liftA2)

Methods

pure :: a -> f a

Lift a value.

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

Sequential application.

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

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

Sequence actions, discarding the value of the first argument.

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

Sequence actions, discarding the value of the second argument.

Instances

Applicative []

Since: base-2.1

Defined in GHC.Base

Methods

pure :: a -> [a]

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

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

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

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

Applicative Maybe

Since: base-2.1

Defined in GHC.Base

Methods

pure :: a -> Maybe a

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

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

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

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

Applicative IO

Since: base-2.1

Defined in GHC.Base

Methods

pure :: a -> IO a

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

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

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

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

Applicative Par1

Since: base-4.9.0.0

Defined in GHC.Generics

Methods

pure :: a -> Par1 a

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

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

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

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

Applicative Q

Defined in Language.Haskell.TH.Syntax

Methods

pure :: a -> Q a

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

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

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

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

Applicative Complex

Since: base-4.9.0.0

Defined in Data.Complex

Methods

pure :: a -> Complex a

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

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

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

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

Applicative Min

Since: base-4.9.0.0

Defined in Data.Semigroup

Methods

pure :: a -> Min a

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

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

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

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

Applicative Max

Since: base-4.9.0.0

Defined in Data.Semigroup

Methods

pure :: a -> Max a

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

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

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

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

Applicative First

Since: base-4.9.0.0

Defined in Data.Semigroup

Methods

pure :: a -> First a

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

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

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

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

Applicative Last

Since: base-4.9.0.0

Defined in Data.Semigroup

Methods

pure :: a -> Last a

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

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

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

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

Applicative Option

Since: base-4.9.0.0

Defined in Data.Semigroup

Methods

pure :: a -> Option a

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

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

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

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

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

Defined in Control.Applicative

Methods

pure :: a -> ZipList a

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

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

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

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

Applicative Identity

Since: base-4.8.0.0

Defined in Data.Functor.Identity

Methods

pure :: a -> Identity a

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

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

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

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

Applicative STM

Since: base-4.8.0.0

Defined in GHC.Conc.Sync

Methods

pure :: a -> STM a

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

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

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

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

Applicative First

Since: base-4.8.0.0

Defined in Data.Monoid

Methods

pure :: a -> First a

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

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

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

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

Applicative Last

Since: base-4.8.0.0

Defined in Data.Monoid

Methods

pure :: a -> Last a

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

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

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

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

Applicative Dual

Since: base-4.8.0.0

Defined in Data.Semigroup.Internal

Methods

pure :: a -> Dual a

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

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

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

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

Applicative Sum

Since: base-4.8.0.0

Defined in Data.Semigroup.Internal

Methods

pure :: a -> Sum a

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

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

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

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

Applicative Product

Since: base-4.8.0.0

Defined in Data.Semigroup.Internal

Methods

pure :: a -> Product a

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

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

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

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

Applicative Down

Since: base-4.11.0.0

Defined in Data.Ord

Methods

pure :: a -> Down a

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

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

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

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

Applicative ReadPrec

Since: base-4.6.0.0

Defined in Text.ParserCombinators.ReadPrec

Methods

pure :: a -> ReadPrec a

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

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

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

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

Applicative ReadP

Since: base-4.6.0.0

Defined in Text.ParserCombinators.ReadP

Methods

pure :: a -> ReadP a

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

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

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

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

Applicative NonEmpty

Since: base-4.9.0.0

Defined in GHC.Base

Methods

pure :: a -> NonEmpty a

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

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

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

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

Applicative PutM

Defined in Data.Binary.Put

Methods

pure :: a -> PutM a

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

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

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

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

Applicative Get

Defined in Data.Binary.Get.Internal

Methods

pure :: a -> Get a

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

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

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

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

Applicative Put

Defined in Data.ByteString.Builder.Internal

Methods

pure :: a -> Put a

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

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

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

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

Applicative Tree

Defined in Data.Tree

Methods

pure :: a -> Tree a

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

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

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

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

Applicative Seq

Since: containers-0.5.4

Defined in Data.Sequence.Internal

Methods

pure :: a -> Seq a

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

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

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

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

Applicative Capability

Defined in System.Console.Terminfo.Base

Methods

pure :: a -> Capability a

(<*>) :: Capability (a -> b) -> Capability a -> Capability b

liftA2 :: (a -> b -> c) -> Capability a -> Capability b -> Capability c

(*>) :: Capability a -> Capability b -> Capability b

(<*) :: Capability a -> Capability b -> Capability a

Applicative P

Since: base-4.5.0.0

Defined in Text.ParserCombinators.ReadP

Methods

pure :: a -> P a

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

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

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

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

Applicative Pair

Defined in Pair

Methods

pure :: a -> Pair a

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

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

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

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

Applicative UniqSM

Defined in UniqSupply

Methods

pure :: a -> UniqSM a

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

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

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

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

Applicative CoreM

Defined in CoreMonad

Methods

pure :: a -> CoreM a

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

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

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

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

Applicative P

Defined in Lexer

Methods

pure :: a -> P a

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

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

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

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

Applicative PD

Defined in CmmMonad

Methods

pure :: a -> PD a

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

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

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

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

Applicative UnifyResultM

Defined in Unify

Methods

pure :: a -> UnifyResultM a

(<*>) :: UnifyResultM (a -> b) -> UnifyResultM a -> UnifyResultM b

liftA2 :: (a -> b -> c) -> UnifyResultM a -> UnifyResultM b -> UnifyResultM c

(*>) :: UnifyResultM a -> UnifyResultM b -> UnifyResultM b

(<*) :: UnifyResultM a -> UnifyResultM b -> UnifyResultM a

Applicative LlvmM

Defined in LlvmCodeGen.Base

Methods

pure :: a -> LlvmM a

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

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

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

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

Applicative FCode

Defined in StgCmmMonad

Methods

pure :: a -> FCode a

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

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

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

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

Applicative CmmParse

Defined in StgCmmExtCode

Methods

pure :: a -> CmmParse a

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

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

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

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

Applicative Hsc

Defined in HscTypes

Methods

pure :: a -> Hsc a

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

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

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

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

Applicative TcPluginM

Defined in TcRnTypes

Methods

pure :: a -> TcPluginM a

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

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

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

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

Applicative CompPipeline

Defined in PipelineMonad

Methods

pure :: a -> CompPipeline a

(<*>) :: CompPipeline (a -> b) -> CompPipeline a -> CompPipeline b

liftA2 :: (a -> b -> c) -> CompPipeline a -> CompPipeline b -> CompPipeline c

(*>) :: CompPipeline a -> CompPipeline b -> CompPipeline b

(<*) :: CompPipeline a -> CompPipeline b -> CompPipeline a

Applicative Ghc

Defined in GhcMonad

Methods

pure :: a -> Ghc a

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

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

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

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

Applicative SimplM

Defined in SimplMonad

Methods

pure :: a -> SimplM a

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

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

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

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

Applicative CpsRn

Defined in RnPat

Methods

pure :: a -> CpsRn a

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

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

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

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

Applicative OccCheckResult

Defined in TcUnify

Methods

pure :: a -> OccCheckResult a

(<*>) :: OccCheckResult (a -> b) -> OccCheckResult a -> OccCheckResult b

liftA2 :: (a -> b -> c) -> OccCheckResult a -> OccCheckResult b -> OccCheckResult c

(*>) :: OccCheckResult a -> OccCheckResult b -> OccCheckResult b

(<*) :: OccCheckResult a -> OccCheckResult b -> OccCheckResult a

Applicative TcS

Defined in TcSMonad

Methods

pure :: a -> TcS a

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

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

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

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

Applicative NatM

Defined in NCGMonad

Methods

pure :: a -> NatM a

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

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

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

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

Applicative (Either e)

Since: base-3.0

Defined in Data.Either

Methods

pure :: a -> Either e a

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

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

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

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

Applicative (U1 :: Type -> Type)

Since: base-4.9.0.0

Defined in GHC.Generics

Methods

pure :: a -> U1 a

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

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

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

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

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

Defined in GHC.Base

Methods

pure :: a0 -> (a, a0)

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

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

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

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

Applicative (ST s)

Since: base-4.4.0.0

Defined in GHC.ST

Methods

pure :: a -> ST s a

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

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

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

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

Monad m => Applicative (WrappedMonad m)

Since: base-2.1

Defined in Control.Applicative

Methods

pure :: a -> WrappedMonad m a

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

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

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

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

Arrow a => Applicative (ArrowMonad a)

Since: base-4.6.0.0

Defined in Control.Arrow

Methods

pure :: a0 -> ArrowMonad a a0

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

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

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

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

Applicative (Proxy :: Type -> Type)

Since: base-4.7.0.0

Defined in Data.Proxy

Methods

pure :: a -> Proxy a

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

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

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

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

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

Defined in Control.Monad.Trans.Maybe

Methods

pure :: a -> MaybeT m a

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

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

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

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

Applicative (ListT f)

Defined in ListT

Methods

pure :: a -> ListT f a

(<*>) :: ListT f (a -> b) -> ListT f a -> ListT f b

liftA2 :: (a -> b -> c) -> ListT f a -> ListT f b -> ListT f c

(*>) :: ListT f a -> ListT f b -> ListT f b

(<*) :: ListT f a -> ListT f b -> ListT f a

Applicative (State s)

Defined in State

Methods

pure :: a -> State s a

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

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

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

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

Applicative (MaybeErr err)

Defined in Maybes

Methods

pure :: a -> MaybeErr err a

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

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

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

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

Applicative (SetM s)

Defined in Data.Graph

Methods

pure :: a -> SetM s a

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

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

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

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

Applicative (CmdLineP s)

Defined in CmdLineParser

Methods

pure :: a -> CmdLineP s a

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

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

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

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

Monad m => Applicative (EwM m)

Defined in CmdLineParser

Methods

pure :: a -> EwM m a

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

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

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

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

Applicative (IOEnv m)

Defined in IOEnv

Methods

pure :: a -> IOEnv m a

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

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

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

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

Applicative (RegM freeRegs)

Defined in RegAlloc.Linear.State

Methods

pure :: a -> RegM freeRegs a

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

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

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

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

Applicative m => Applicative (GhcT m)

Defined in GhcMonad

Methods

pure :: a -> GhcT m a

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

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

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

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

Applicative f => Applicative (Rec1 f)

Since: base-4.9.0.0

Defined in GHC.Generics

Methods

pure :: a -> Rec1 f a

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

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

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

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

Arrow a => Applicative (WrappedArrow a b)

Since: base-2.1

Defined in Control.Applicative

Methods

pure :: a0 -> WrappedArrow a b a0

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

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

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

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

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

Since: base-2.0.1

Defined in Data.Functor.Const

Methods

pure :: a -> Const m a

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

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

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

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

Applicative f => Applicative (Ap f)

Since: base-4.12.0.0

Defined in Data.Monoid

Methods

pure :: a -> Ap f a

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

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

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

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

Applicative f => Applicative (Alt f)

Since: base-4.8.0.0

Defined in Data.Semigroup.Internal

Methods

pure :: a -> Alt f a

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

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

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

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

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

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

Since: containers-0.5.9

Defined in Data.IntMap.Internal

Methods

pure :: a -> WhenMissing f x a

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

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

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

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

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

Defined in Control.Monad.Trans.Writer.Lazy

Methods

pure :: a -> WriterT w m a

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

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

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

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

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

Defined in Control.Monad.Trans.State.Strict

Methods

pure :: a -> StateT s m a

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

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

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

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

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

Defined in Control.Monad.Trans.State.Lazy

Methods

pure :: a -> StateT s m a

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

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

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

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

Applicative m => Applicative (ReaderT r m)

Defined in Control.Monad.Trans.Reader

Methods

pure :: a -> ReaderT r m a

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

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

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

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

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

Defined in Control.Monad.Trans.Except

Methods

pure :: a -> ExceptT e m a

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

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

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

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

Monad m => Applicative (Stream m a)

Defined in Stream

Methods

pure :: a0 -> Stream m a a0

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

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

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

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

Applicative ((->) a :: Type -> Type)

Since: base-2.1

Defined in GHC.Base

Methods

pure :: a0 -> a -> a0

(<*>) :: (a -> (a0 -> b)) -> (a -> a0) -> a -> b

liftA2 :: (a0 -> b -> c) -> (a -> a0) -> (a -> b) -> a -> c

(*>) :: (a -> a0) -> (a -> b) -> a -> b

(<*) :: (a -> a0) -> (a -> b) -> a -> a0

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

Since: base-4.12.0.0

Defined in GHC.Generics

Methods

pure :: a -> K1 i c a

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

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

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

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

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

Since: base-4.9.0.0

Defined in GHC.Generics

Methods

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

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

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

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

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

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

Since: base-4.9.0.0

Defined in Data.Functor.Product

Methods

pure :: a -> Product f g a

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

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

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

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

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

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

Since: containers-0.5.9

Defined in Data.IntMap.Internal

Methods

pure :: a -> WhenMatched f x y a

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

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

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

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

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

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

Since: containers-0.5.9

Defined in Data.Map.Internal

Methods

pure :: a -> WhenMissing f k x a

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

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

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

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

Applicative f => Applicative (M1 i c f)

Since: base-4.9.0.0

Defined in GHC.Generics

Methods

pure :: a -> M1 i c f a

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

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

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

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

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

Since: base-4.9.0.0

Defined in GHC.Generics

Methods

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

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

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

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

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

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

Since: base-4.9.0.0

Defined in Data.Functor.Compose

Methods

pure :: a -> Compose f g a

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

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

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

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

(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

Defined in Data.Map.Internal

Methods

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

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

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

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

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

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

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

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

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

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

MonadFix []

Since: base-2.1

Defined in Control.Monad.Fix

Methods

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

MonadFix Maybe

Since: base-2.1

Defined in Control.Monad.Fix

Methods

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

MonadFix IO

Since: base-2.1

Defined in Control.Monad.Fix

Methods

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

MonadFix Par1

Since: base-4.9.0.0

Defined in Control.Monad.Fix

Methods

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

MonadFix Min

Since: base-4.9.0.0

Defined in Data.Semigroup

Methods

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

MonadFix Max

Since: base-4.9.0.0

Defined in Data.Semigroup

Methods

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

MonadFix First

Since: base-4.9.0.0

Defined in Data.Semigroup

Methods

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

MonadFix Last

Since: base-4.9.0.0

Defined in Data.Semigroup

Methods

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

MonadFix Option

Since: base-4.9.0.0

Defined in Data.Semigroup

Methods

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

MonadFix Identity

Since: base-4.8.0.0

Defined in Data.Functor.Identity

Methods

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

MonadFix First

Since: base-4.8.0.0

Defined in Control.Monad.Fix

Methods

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

MonadFix Last

Since: base-4.8.0.0

Defined in Control.Monad.Fix

Methods

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

MonadFix Dual

Since: base-4.8.0.0

Defined in Control.Monad.Fix

Methods

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

MonadFix Sum

Since: base-4.8.0.0

Defined in Control.Monad.Fix

Methods

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

MonadFix Product

Since: base-4.8.0.0

Defined in Control.Monad.Fix

Methods

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

MonadFix Down

Since: base-4.12.0.0

Defined in Control.Monad.Fix

Methods

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

MonadFix NonEmpty

Since: base-4.9.0.0

Defined in Control.Monad.Fix

Methods

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

MonadFix Tree

Since: containers-0.5.11

Defined in Data.Tree

Methods

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

MonadFix Seq

Since: containers-0.5.11

Defined in Data.Sequence.Internal

Methods

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

MonadFix UniqSM

Defined in UniqSupply

Methods

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

MonadFix Ghc

Defined in GhcMonad

Methods

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

MonadFix (Either e)

Since: base-4.3.0.0

Defined in Control.Monad.Fix

Methods

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

MonadFix (ST s)

Since: base-2.1

Defined in Control.Monad.Fix

Methods

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

MonadFix m => MonadFix (MaybeT m)

Defined in Control.Monad.Trans.Maybe

Methods

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

MonadFix f => MonadFix (Rec1 f)

Since: base-4.9.0.0

Defined in Control.Monad.Fix

Methods

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

MonadFix f => MonadFix (Ap f)

Since: base-4.12.0.0

Defined in Control.Monad.Fix

Methods

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

MonadFix f => MonadFix (Alt f)

Since: base-4.8.0.0

Defined in Control.Monad.Fix

Methods

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

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

Defined in Control.Monad.Trans.Writer.Lazy

Methods

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

MonadFix m => MonadFix (StateT s m)

Defined in Control.Monad.Trans.State.Strict

Methods

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

MonadFix m => MonadFix (StateT s m)

Defined in Control.Monad.Trans.State.Lazy

Methods

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

MonadFix m => MonadFix (ReaderT r m)

Defined in Control.Monad.Trans.Reader

Methods

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

MonadFix m => MonadFix (ExceptT e m)

Defined in Control.Monad.Trans.Except

Methods

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

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

Since: base-2.1

Defined in Control.Monad.Fix

Methods

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

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

Since: base-4.9.0.0

Defined in Control.Monad.Fix

Methods

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

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

Since: base-4.9.0.0

Defined in Data.Functor.Product

Methods

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

MonadFix f => MonadFix (M1 i c f)

Since: base-4.9.0.0

Defined in Control.Monad.Fix

Methods

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

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

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:

• liftIO . return = return

• liftIO (m >>= f) = liftIO m >>= (liftIO . f)

Methods

liftIO :: IO a -> m a

Lift a computation from the IO monad.

Instances

MonadIO IO

Since: base-4.9.0.0

Defined in Control.Monad.IO.Class

Methods

liftIO :: IO a -> IO a

MonadIO Q

Defined in Language.Haskell.TH.Syntax

Methods

liftIO :: IO a -> Q a

MonadIO CoreM

Defined in CoreMonad

Methods

liftIO :: IO a -> CoreM a

MonadIO Hsc

Defined in HscTypes

Methods

liftIO :: IO a -> Hsc a

MonadIO CompPipeline

Defined in PipelineMonad

Methods

liftIO :: IO a -> CompPipeline a

MonadIO Ghc

Defined in GhcMonad

Methods

liftIO :: IO a -> Ghc a

MonadIO SimplM

Defined in SimplMonad

Methods

liftIO :: IO a -> SimplM a

MonadIO m => MonadIO (MaybeT m)

Defined in Control.Monad.Trans.Maybe

Methods

liftIO :: IO a -> MaybeT m a

MonadIO (IOEnv env)

Defined in IOEnv

Methods

liftIO :: IO a -> IOEnv env a

MonadIO m => MonadIO (GhcT m)

Defined in GhcMonad

Methods

liftIO :: IO a -> GhcT m a

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

Defined in Control.Monad.Trans.Writer.Lazy

Methods

liftIO :: IO a -> WriterT w m a

MonadIO m => MonadIO (StateT s m)

Defined in Control.Monad.Trans.State.Strict

Methods

liftIO :: IO a -> StateT s m a

MonadIO m => MonadIO (StateT s m)

Defined in Control.Monad.Trans.State.Lazy

Methods

liftIO :: IO a -> StateT s m a

MonadIO m => MonadIO (ReaderT r m)

Defined in Control.Monad.Trans.Reader

Methods

liftIO :: IO a -> ReaderT r m a

MonadIO m => MonadIO (ExceptT e m)

Defined in Control.Monad.Trans.Except

Methods

liftIO :: IO a -> ExceptT e m a

liftIO1 :: MonadIO m => (a -> IO b) -> a -> m b

Lift an IO operation with 1 argument into another monad

liftIO2 :: MonadIO m => (a -> b -> IO c) -> a -> b -> m c

Lift an IO operation with 2 arguments into another monad

liftIO3 :: MonadIO m => (a -> b -> c -> IO d) -> a -> b -> c -> m d

Lift an IO operation with 3 arguments into another monad

liftIO4 :: MonadIO m => (a -> b -> c -> d -> IO e) -> a -> b -> c -> d -> m e

Lift an IO operation with 4 arguments into another monad

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

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

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

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

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

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-transforming monad.

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

mapAndUnzipM for triples

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

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

mapAccumLM

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)]

Monadic version of mapSnd

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

Monadic version of concatMap

mapMaybeM :: Monad m => (a -> m (Maybe b)) -> [a] -> m [b]

Monadic version of mapMaybe

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

Monadic version of fmap

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

Monadic version of fmap

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

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

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

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

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

Monadic version of or

foldlM :: Monad m => (a -> b -> m a) -> a -> [b] -> m a

Monadic version of foldl

foldlM_ :: Monad m => (a -> b -> m a) -> a -> [b] -> m ()

Monadic version of foldl that discards its result

foldrM :: Monad m => (b -> a -> m a) -> a -> [b] -> m a

Monadic version of foldr

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

Monadic version of fmap specialised for Maybe

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

Monadic version of when, taking the condition in the monad

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

Monadic version of unless, taking the condition in the monad