ghc-9.6.3: The GHC API

Safe Haskell | Safe-Inferred
Language | Haskell2010

GHC.Utils.Monad

Description

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

Synopsis

- class Functor f => Applicative (f :: Type -> Type) where
  - pure :: a -> f a
  - (<*>) :: f (a -> b) -> f a -> f b
  - liftA2 :: (a -> b -> c) -> f a -> f b -> f c
  - (*>) :: f a -> f b -> f b
  - (<*) :: f a -> f b -> f a
- (<$>) :: Functor f => (a -> b) -> f a -> f b
- class Monad m => MonadFix (m :: Type -> Type) where
  - mfix :: (a -> m a) -> m a
- class Monad m => MonadIO (m :: Type -> Type) where
  - liftIO :: IO a -> m a
- 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])
- mapAndUnzip3M :: Monad m => (a -> m (b, c, d)) -> [a] -> m ([b], [c], [d])
- 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 :: (Monad m, Traversable t) => (acc -> x -> m (acc, y)) -> acc -> t x -> m (acc, t y)
- mapSndM :: (Applicative m, Traversable f) => (b -> m c) -> f (a, b) -> m (f (a, c))
- concatMapM :: (Monad m, Traversable f) => (a -> m [b]) -> f a -> m [b]
- mapMaybeM :: Applicative m => (a -> m (Maybe b)) -> [a] -> m [b]
- anyM :: (Monad m, Foldable f) => (a -> m Bool) -> f a -> m Bool
- allM :: (Monad m, Foldable f) => (a -> m Bool) -> f a -> m Bool
- orM :: Monad m => m Bool -> m Bool -> m Bool
- foldlM :: (Foldable t, Monad m) => (b -> a -> m b) -> b -> t a -> m b
- foldlM_ :: (Monad m, Foldable t) => (a -> b -> m a) -> a -> t b -> m ()
- foldrM :: (Foldable t, Monad m) => (a -> b -> m b) -> b -> t a -> m b
- whenM :: Monad m => m Bool -> m () -> m ()
- unlessM :: Monad m => m Bool -> m () -> m ()
- filterOutM :: Applicative m => (a -> m Bool) -> [a] -> m [a]
- partitionM :: Monad m => (a -> m Bool) -> [a] -> m ([a], [a])

# 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:

-     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

-     m1 <*> m2 = m1 >>= (\x1 -> m2 >>= (\x2 -> return (x1 x2)))

-     (*>) = (>>)

(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.

#### Example

Expand

Used in combination with `(`<$>`)`, `(`<*>`)` can be used to build a record.

    >>> data MyState = MyState {arg1 :: Foo, arg2 :: Bar, arg3 :: Baz}

    >>> produceFoo :: Applicative f => f Foo

    >>> produceBar :: Applicative f => f Bar
    >>> produceBaz :: Applicative f => f Baz

    >>> mkState :: Applicative f => f MyState
    >>> mkState = MyState <$> produceFoo <*> produceBar <*> produceBaz

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`.

#### Example

Expand

    >>> liftA2 (,) (Just 3) (Just 5)
    Just (3,5)

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

Sequence actions, discarding the value of the first argument.

#### Examples

Expand

If used in conjunction with the Applicative instance for `Maybe`, you can chain Maybe computations, with a possible "early return" in case of `Nothing`.

    >>> Just 2 *> Just 3
    Just 3

    >>> Nothing *> Just 3
    Nothing

Of course a more interesting use case would be to have effectful computations instead of just returning pure values.

    >>> import Data.Char
    >>> import Text.ParserCombinators.ReadP
    >>> let p = string "my name is " *> munch1 isAlpha <* eof
    >>> readP_to_S p "my name is Simon"
    [("Simon","")]

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

Sequence actions, discarding the value of the second argument.

#### Instances

Instances details

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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 PD Source # |
Instance details Defined in GHC.Cmm.Parser.Monad 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 NatM Source # |
Instance details Defined in GHC.CmmToAsm.Monad 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 LlvmM Source # |
Instance details Defined in GHC.CmmToLlvm.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 CoreM Source # |
Instance details Defined in GHC.Core.Opt.Monad 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 SimplM Source # |
Instance details Defined in GHC.Core.Opt.Simplify.Monad 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 UnifyResultM Source # |
Instance details Defined in GHC.Core.Unify Methods pure :: a -> UnifyResultM a Source # (<*>) :: UnifyResultM (a -> b) -> UnifyResultM a -> UnifyResultM b Source # liftA2 :: (a -> b -> c) -> UnifyResultM a -> UnifyResultM b -> UnifyResultM c Source # (*>) :: UnifyResultM a -> UnifyResultM b -> UnifyResultM b Source # (<*) :: UnifyResultM a -> UnifyResultM b -> UnifyResultM a Source #
Applicative NullCollapseViz Source # |

Instance details

Defined in GHC.Data.Graph.Collapse

Methods

pure :: a -> NullCollapseViz a Source #

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

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

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

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

Applicative Infinite Source # |
Instance details Defined in GHC.Data.List.Infinite Methods pure :: a -> Infinite a Source # (<*>) :: Infinite (a -> b) -> Infinite a -> Infinite b Source # liftA2 :: (a -> b -> c) -> Infinite a -> Infinite b -> Infinite c Source # (*>) :: Infinite a -> Infinite b -> Infinite b Source # (<*) :: Infinite a -> Infinite b -> Infinite a Source #
Applicative Pair Source # |
Instance details Defined in GHC.Data.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 Maybe Source # |
Instance details Defined in GHC.Data.Strict 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 Hsc Source # |
Instance details Defined in GHC.Driver.Env.Types 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 Ghc Source # |
Instance details Defined in GHC.Driver.Monad 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 HookedUse Source # |
Instance details Defined in GHC.Driver.Pipeline.Execute Methods pure :: a -> HookedUse a Source # (<*>) :: HookedUse (a -> b) -> HookedUse a -> HookedUse b Source # liftA2 :: (a -> b -> c) -> HookedUse a -> HookedUse b -> HookedUse c Source # (*>) :: HookedUse a -> HookedUse b -> HookedUse b Source # (<*) :: HookedUse a -> HookedUse b -> HookedUse a Source #
Applicative MatchResult Source # | Product is an "or" on fallibility---the combined match result is infallible only if the left and right argument match results both were. This is useful for combining a bunch of alternatives together and then getting the overall fallibility of the entire group. See `mkDataConCase` for an example.
Instance details Defined in GHC.HsToCore.Monad Methods pure :: a -> MatchResult a Source # (<*>) :: MatchResult (a -> b) -> MatchResult a -> MatchResult b Source # liftA2 :: (a -> b -> c) -> MatchResult a -> MatchResult b -> MatchResult c Source # (*>) :: MatchResult a -> MatchResult b -> MatchResult b Source # (<*) :: MatchResult a -> MatchResult b -> MatchResult a Source #
Applicative P Source # |
Instance details Defined in GHC.Parser.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 PV Source # |
Instance details Defined in GHC.Parser.PostProcess 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 CpsRn Source # |
Instance details Defined in GHC.Rename.Pat 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 LiftM Source # |
Instance details Defined in GHC.Stg.Lift.Monad 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 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 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 TcS Source # |
Instance details Defined in GHC.Tc.Solver.Monad 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 TcPluginM Source # |
Instance details Defined in GHC.Tc.Types 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 UniqSM Source # |
Instance details Defined in GHC.Types.Unique.Supply 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 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 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 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 Solo | Since: base-4.15
Instance details Defined in GHC.Base Methods pure :: a -> Solo a Source # (<*>) :: Solo (a -> b) -> Solo a -> Solo b Source # liftA2 :: (a -> b -> c) -> Solo a -> Solo b -> Solo c Source # (*>) :: Solo a -> Solo b -> Solo b Source # (<*) :: Solo a -> Solo b -> Solo a Source #
Applicative List | 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 #
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 (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 (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 #
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 #
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 #
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 (RegM freeRegs) Source # |

Instance details

Defined in GHC.CmmToAsm.Reg.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 (WasmCodeGenM w) Source # |

Instance details

Defined in GHC.CmmToAsm.Wasm.Types

Methods

pure :: a -> WasmCodeGenM w a Source #

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

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

(*>) :: WasmCodeGenM w a -> WasmCodeGenM w b -> WasmCodeGenM w b Source #

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

Applicative (IOEnv m) Source # |
Instance details Defined in GHC.Data.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 (MaybeErr err) Source # |
Instance details Defined in GHC.Data.Maybe 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 #
Monad m => Applicative (EwM m) Source # |
Instance details Defined in GHC.Driver.CmdLine 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 m => Applicative (GhcT m) Source # |
Instance details Defined in GHC.Driver.Monad 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 (CmdLineP s) Source # |
Instance details Defined in GHC.Driver.Session 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 #
Applicative (State s) Source # |
Instance details Defined in GHC.Utils.Monad.State.Strict 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 #
(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 #

Monoid a => Applicative ((,) a)

For tuples, the `Monoid` constraint on `a` determines how the first values merge. For example, `String`s 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 #
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 #
(Generic1 f, Applicative (Rep1 f)) => Applicative (Generically1 f) | Since: base-4.17.0.0

Instance details

Defined in GHC.Generics

Methods

pure :: a -> Generically1 f a Source #

(<*>) :: Generically1 f (a -> b) -> Generically1 f a -> Generically1 f b Source #

liftA2 :: (a -> b -> c) -> Generically1 f a -> Generically1 f b -> Generically1 f c Source #

(*>) :: Generically1 f a -> Generically1 f b -> Generically1 f b Source #

(<*) :: Generically1 f a -> Generically1 f b -> Generically1 f 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 #
(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 #

Applicative (Stream m a) Source # |
Instance details Defined in GHC.Data.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 #
Monad m => Applicative (StreamS m a) Source # |
Instance details Defined in GHC.Data.Stream Methods pure :: a0 -> StreamS m a a0 Source # (<*>) :: StreamS m a (a0 -> b) -> StreamS m a a0 -> StreamS m a b Source # liftA2 :: (a0 -> b -> c) -> StreamS m a a0 -> StreamS m a b -> StreamS m a c Source # (*>) :: StreamS m a a0 -> StreamS m a b -> StreamS m a b Source # (<*) :: StreamS m a a0 -> StreamS m a b -> StreamS m a a0 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 #
Applicative m => Applicative (IdentityT m) |
Instance details Defined in Control.Monad.Trans.Identity Methods pure :: a -> IdentityT m a Source # (<*>) :: IdentityT m (a -> b) -> IdentityT m a -> IdentityT m b Source # liftA2 :: (a -> b -> c) -> IdentityT m a -> IdentityT m b -> IdentityT m c Source # (*>) :: IdentityT m a -> IdentityT m b -> IdentityT m b Source # (<*) :: IdentityT m a -> IdentityT m b -> IdentityT 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 (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 #
(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 (WriterT w m) |
Instance details Defined in Control.Monad.Trans.Writer.CPS 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 #
(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 #
(Monoid w, Applicative m) => Applicative (WriterT w m) |
Instance details Defined in Control.Monad.Trans.Writer.Strict 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 #
(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 #
(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 #
(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 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 #
(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 #
(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 ((->) r) | 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 #
(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 #
(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 (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 #
(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 #

(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 #
(Monoid w, Functor m, Monad m) => Applicative (RWST r w s m) |
Instance details Defined in Control.Monad.Trans.RWS.Lazy 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 #
(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 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 Complex | Since: base-4.15.0.0
Instance details Defined in Data.Complex Methods mfix :: (a -> Complex a) -> Complex 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 Down | Since: base-4.12.0.0
Instance details Defined in Control.Monad.Fix Methods mfix :: (a -> Down a) -> Down 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 Max | Since: base-4.9.0.0
Instance details Defined in Data.Semigroup Methods mfix :: (a -> Max a) -> Max 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 Dual | Since: base-4.8.0.0
Instance details Defined in Control.Monad.Fix Methods mfix :: (a -> Dual a) -> Dual 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 Sum | Since: base-4.8.0.0
Instance details Defined in Control.Monad.Fix Methods mfix :: (a -> Sum a) -> Sum 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 Par1 | Since: base-4.9.0.0
Instance details Defined in Control.Monad.Fix Methods mfix :: (a -> Par1 a) -> Par1 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 Tree | Since: containers-0.5.11
Instance details Defined in Data.Tree Methods mfix :: (a -> Tree a) -> Tree a Source #
MonadFix Ghc Source # |
Instance details Defined in GHC.Driver.Monad Methods mfix :: (a -> Ghc a) -> Ghc a Source #
MonadFix TcS Source # |
Instance details Defined in GHC.Tc.Solver.Monad Methods mfix :: (a -> TcS a) -> TcS a Source #
MonadFix UniqSM Source # |
Instance details Defined in GHC.Types.Unique.Supply Methods mfix :: (a -> UniqSM a) -> UniqSM a Source #
MonadFix IO | Since: base-2.1
Instance details Defined in Control.Monad.Fix Methods mfix :: (a -> IO a) -> IO a Source #
MonadFix Q | If the function passed to `mfix` inspects its argument, the resulting action will throw a `FixIOException`. Since: template-haskell-2.17.0.0
Instance details Defined in Language.Haskell.TH.Syntax Methods mfix :: (a -> Q a) -> Q a Source #
MonadFix Maybe | Since: base-2.1
Instance details Defined in Control.Monad.Fix Methods mfix :: (a -> Maybe a) -> Maybe a Source #
MonadFix Solo | Since: base-4.15
Instance details Defined in Control.Monad.Fix Methods mfix :: (a -> Solo a) -> Solo a Source #
MonadFix List | Since: base-2.1
Instance details Defined in Control.Monad.Fix Methods mfix :: (a -> [a]) -> [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 (IOEnv env) Source # |
Instance details Defined in GHC.Data.IOEnv Methods mfix :: (a -> IOEnv env a) -> IOEnv env a Source #
MonadFix m => MonadFix (GhcT m) Source # |
Instance details Defined in GHC.Driver.Monad Methods mfix :: (a -> GhcT m a) -> GhcT m 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 (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 #
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 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 m => MonadFix (IdentityT m) |
Instance details Defined in Control.Monad.Trans.Identity Methods mfix :: (a -> IdentityT m a) -> IdentityT 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 (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 (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 (WriterT w m) |
Instance details Defined in Control.Monad.Trans.Writer.CPS Methods mfix :: (a -> WriterT w m a) -> WriterT w m 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 #
(Monoid w, MonadFix m) => MonadFix (WriterT w m) |
Instance details Defined in Control.Monad.Trans.Writer.Strict Methods mfix :: (a -> WriterT w m a) -> WriterT w m 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 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 ((->) r) | Since: base-2.1
Instance details Defined in Control.Monad.Fix Methods mfix :: (a -> r -> a) -> r -> 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 #
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 #
(Monoid w, MonadFix m) => MonadFix (RWST r w s m) |
Instance details Defined in Control.Monad.Trans.RWS.Lazy Methods mfix :: (a -> RWST r w s m a) -> RWST r w s m 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 #

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:

-     liftIO . return = return

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

Methods

liftIO :: IO a -> m a Source #

Lift a computation from the `IO` monad. This allows us to run IO computations in any monadic stack, so long as it supports these kinds of operations (i.e. `IO` is the base monad for the stack).

### Example

Expand

    import Control.Monad.Trans.State -- from the "transformers" library

    printState :: Show s => StateT s IO ()
    printState = do
      state <- get
      liftIO $ print state

Had we omitted ``liftIO``, we would have ended up with this error:

    • Couldn't match type ‘IO’ with ‘StateT s IO’
     Expected type: StateT s IO ()
       Actual type: IO ()

The important part here is the mismatch between `StateT s IO ()` and ``IO` ()`.

Luckily, we know of a function that takes an ``IO` a` and returns an `(m a)`: ``liftIO``, enabling us to run the program and see the expected results:

    > evalStateT printState "hello"
    "hello"

    > evalStateT printState 3
    3

#### Instances

Instances details

MonadIO CoreM Source # |
Instance details Defined in GHC.Core.Opt.Monad Methods liftIO :: IO a -> CoreM a Source #
MonadIO SimplM Source # |
Instance details Defined in GHC.Core.Opt.Simplify.Monad Methods liftIO :: IO a -> SimplM a Source #
MonadIO Hsc Source # |
Instance details Defined in GHC.Driver.Env.Types Methods liftIO :: IO a -> Hsc a Source #
MonadIO Ghc Source # |
Instance details Defined in GHC.Driver.Monad Methods liftIO :: IO a -> Ghc a Source #
MonadIO HookedUse Source # |
Instance details Defined in GHC.Driver.Pipeline.Execute Methods liftIO :: IO a -> HookedUse a Source #
MonadIO TcS Source # |
Instance details Defined in GHC.Tc.Solver.Monad Methods liftIO :: IO a -> TcS a Source #
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 (IOEnv env) Source # |
Instance details Defined in GHC.Data.IOEnv Methods liftIO :: IO a -> IOEnv env a Source #
MonadIO m => MonadIO (EwM m) Source # |
Instance details Defined in GHC.Driver.CmdLine Methods liftIO :: IO a -> EwM m a Source #
MonadIO m => MonadIO (GhcT m) Source # |
Instance details Defined in GHC.Driver.Monad Methods liftIO :: IO a -> GhcT m a Source #
MonadIO m => MonadIO (MaybeT m) |
Instance details Defined in Control.Monad.Trans.Maybe Methods liftIO :: IO a -> MaybeT m a Source #
MonadIO m => MonadIO (Stream m b) Source # |
Instance details Defined in GHC.Data.Stream Methods liftIO :: IO a -> Stream m b 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 (IdentityT m) |
Instance details Defined in Control.Monad.Trans.Identity Methods liftIO :: IO a -> IdentityT 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 (StateT s m) |
Instance details Defined in Control.Monad.Trans.State.Lazy Methods liftIO :: IO a -> StateT s 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 (WriterT w m) |
Instance details Defined in Control.Monad.Trans.Writer.CPS Methods liftIO :: IO a -> WriterT w 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 #
(Monoid w, MonadIO m) => MonadIO (WriterT w m) |
Instance details Defined in Control.Monad.Trans.Writer.Strict Methods liftIO :: IO a -> WriterT w 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 #
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 #
(Monoid w, MonadIO m) => MonadIO (RWST r w s m) |
Instance details Defined in Control.Monad.Trans.RWS.Lazy Methods liftIO :: IO a -> RWST r w s 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 #

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, Traversable t) |
=> (acc -> x -> m (acc, y)) | combining function
-> acc | initial state
-> t x | inputs
-> m (acc, t y) | final state, outputs

Monadic version of mapAccumL

mapSndM :: (Applicative m, Traversable f) => (b -> m c) -> f (a, b) -> m (f (a, c)) Source #

Monadic version of mapSnd

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

Monadic version of concatMap

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

Applicative version of mapMaybe

anyM :: (Monad m, Foldable f) => (a -> m Bool) -> f a -> m Bool Source #

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

allM :: (Monad m, Foldable f) => (a -> m Bool) -> f 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 #

Left-to-right monadic fold over the elements of a structure.

Given a structure `t` with elements `(a, b, ..., w, x, y)`, the result of a fold with an operator function `f` is equivalent to:

    foldlM f z t = do
        aa <- f z a
        bb <- f aa b
        ...
        xx <- f ww x
        yy <- f xx y
        return yy -- Just @return z@ when the structure is empty

For a Monad `m`, given two functions `f1 :: a -> m b` and `f2 :: b -> m c`, their Kleisli composition `(f1 >=> f2) :: a -> m c` is defined by:

    (f1 >=> f2) a = f1 a >>= f2

Another way of thinking about `foldlM` is that it amounts to an application to `z` of a Kleisli composition:

    foldlM f z t =
        flip f a >=> flip f b >=> ... >=> flip f x >=> flip f y $ z

The monadic effects of `foldlM` are sequenced from left to right.

If at some step the bind operator `(`>>=`)` short-circuits (as with, e.g., `mzero` in a `MonadPlus`), the evaluated effects will be from an initial segment of the element sequence. If you want to evaluate the monadic effects in right-to-left order, or perhaps be able to short-circuit after processing a tail of the sequence of elements, you'll need to use `foldrM` instead.

If the monadic effects don't short-circuit, the outermost application of `f` is to the rightmost element `y`, so that, ignoring effects, the result looks like a left fold:

    ((((z `f` a) `f` b) ... `f` w) `f` x) `f` y

#### Examples

Expand

Basic usage:

    >>> let f a e = do { print e ; return $ e : a }
    >>> foldlM f [] [0..3]
    0
    1
    2
    3
    [3,2,1,0]

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 #

Right-to-left monadic fold over the elements of a structure.

Given a structure `t` with elements `(a, b, c, ..., x, y)`, the result of a fold with an operator function `f` is equivalent to:

    foldrM f z t = do
        yy <- f y z
        xx <- f x yy
        ...
        bb <- f b cc
        aa <- f a bb
        return aa -- Just @return z@ when the structure is empty

For a Monad `m`, given two functions `f1 :: a -> m b` and `f2 :: b -> m c`, their Kleisli composition `(f1 >=> f2) :: a -> m c` is defined by:

    (f1 >=> f2) a = f1 a >>= f2

Another way of thinking about `foldrM` is that it amounts to an application to `z` of a Kleisli composition:

    foldrM f z t = f y >=> f x >=> ... >=> f b >=> f a $ z

The monadic effects of `foldrM` are sequenced from right to left, and e.g. folds of infinite lists will diverge.

If at some step the bind operator `(`>>=`)` short-circuits (as with, e.g., `mzero` in a `MonadPlus`), the evaluated effects will be from a tail of the element sequence. If you want to evaluate the monadic effects in left-to-right order, or perhaps be able to short-circuit after an initial sequence of elements, you'll need to use `foldlM` instead.

If the monadic effects don't short-circuit, the outermost application of `f` is to the leftmost element `a`, so that, ignoring effects, the result looks like a right fold:

    a `f` (b `f` (c `f` (... (x `f` (y `f` z))))).

#### Examples

Expand

Basic usage:

    >>> let f i acc = do { print i ; return $ i : acc }
    >>> foldrM f [] [0..3]
    3
    2
    1
    0
    [0,1,2,3]

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.

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

Monadic version of `partition`