Safe Haskell	Trustworthy
Language	Haskell2010

Pipes

Contents

The Proxy Monad Transformer
ListT
Utilities
Re-exports

Description

This module is the recommended entry point to the pipes library.

Read Pipes.Tutorial if you want a tutorial explaining how to use this library.

Synopsis

data Proxy a' a b' b m r
type X = Void
type Effect = Proxy X () () X
type Effect' m r = forall x' x y' y. Proxy x' x y' y m r
runEffect :: Monad m => Effect m r -> m r
type Producer b = Proxy X () () b
type Producer' b m r = forall x' x. Proxy x' x () b m r
yield :: Functor m => a -> Proxy x' x () a m ()
for :: Functor m => Proxy x' x b' b m a' -> (b -> Proxy x' x c' c m b') -> Proxy x' x c' c m a'
(~>) :: Functor m => (a -> Proxy x' x b' b m a') -> (b -> Proxy x' x c' c m b') -> a -> Proxy x' x c' c m a'
(<~) :: Functor m => (b -> Proxy x' x c' c m b') -> (a -> Proxy x' x b' b m a') -> a -> Proxy x' x c' c m a'
type Consumer a = Proxy () a () X
type Consumer' a m r = forall y' y. Proxy () a y' y m r
await :: Functor m => Consumer' a m a
(>~) :: Functor m => Proxy a' a y' y m b -> Proxy () b y' y m c -> Proxy a' a y' y m c
(~<) :: Functor m => Proxy () b y' y m c -> Proxy a' a y' y m b -> Proxy a' a y' y m c
type Pipe a b = Proxy () a () b
cat :: Functor m => Pipe a a m r
(>->) :: Functor m => Proxy a' a () b m r -> Proxy () b c' c m r -> Proxy a' a c' c m r
(<-<) :: Functor m => Proxy () b c' c m r -> Proxy a' a () b m r -> Proxy a' a c' c m r
newtype ListT m a = Select {
- enumerate :: Producer a m ()
}
runListT :: Monad m => ListT m a -> m ()
class Enumerable t where
- toListT :: Monad m => t m a -> ListT m a
next :: Monad m => Producer a m r -> m (Either r (a, Producer a m r))
each :: (Functor m, Foldable f) => f a -> Proxy x' x () a m ()
every :: (Monad m, Enumerable t) => t m a -> Proxy x' x () a m ()
discard :: Monad m => a -> m ()
class (Alternative m, Monad m) => MonadPlus (m :: Type -> Type) where
- mzero :: m a
- mplus :: m a -> m a -> m a
void :: Functor f => f a -> f ()
class Monad m => MonadIO (m :: Type -> Type) where
- liftIO :: IO a -> m a
class (forall (m :: Type -> Type). Monad m => Monad (t m)) => MonadTrans (t :: (Type -> Type) -> Type -> Type) where
- lift :: Monad m => m a -> t m a
class (MFunctor t, MonadTrans t) => MMonad (t :: (Type -> Type) -> Type -> Type) where
- embed :: forall (n :: Type -> Type) m b. Monad n => (forall a. m a -> t n a) -> t m b -> t n b
class MFunctor (t :: (Type -> Type) -> k -> Type) where
- hoist :: forall m n (b :: k). Monad m => (forall a. m a -> n a) -> t m b -> t n b
class Foldable (t :: Type -> Type)

The Proxy Monad Transformer

data Proxy a' a b' b m r Source #

A Proxy is a monad transformer that receives and sends information on both an upstream and downstream interface.

The type variables signify:

a' and a - The upstream interface, where (a')s go out and (a)s come in
b' and b - The downstream interface, where (b)s go out and (b')s come in
m - The base monad
r - The return value

Instances

Instances details

MFunctor (Proxy a' a b' b :: (Type -> Type) -> Type -> Type) Source #
Instance details Defined in Pipes.Internal Methods hoist :: forall m n (b0 :: k). Monad m => (forall a0. m a0 -> n a0) -> Proxy a' a b' b m b0 -> Proxy a' a b' b n b0 Source #
MonadError e m => MonadError e (Proxy a' a b' b m) Source #
Instance details Defined in Pipes.Internal Methods throwError :: e -> Proxy a' a b' b m a0 # catchError :: Proxy a' a b' b m a0 -> (e -> Proxy a' a b' b m a0) -> Proxy a' a b' b m a0 #
MonadReader r m => MonadReader r (Proxy a' a b' b m) Source #
Instance details Defined in Pipes.Internal Methods ask :: Proxy a' a b' b m r # local :: (r -> r) -> Proxy a' a b' b m a0 -> Proxy a' a b' b m a0 # reader :: (r -> a0) -> Proxy a' a b' b m a0 #
MonadState s m => MonadState s (Proxy a' a b' b m) Source #
Instance details Defined in Pipes.Internal Methods get :: Proxy a' a b' b m s # put :: s -> Proxy a' a b' b m () # state :: (s -> (a0, s)) -> Proxy a' a b' b m a0 #
MonadWriter w m => MonadWriter w (Proxy a' a b' b m) Source #
Instance details Defined in Pipes.Internal Methods writer :: (a0, w) -> Proxy a' a b' b m a0 # tell :: w -> Proxy a' a b' b m () # listen :: Proxy a' a b' b m a0 -> Proxy a' a b' b m (a0, w) # pass :: Proxy a' a b' b m (a0, w -> w) -> Proxy a' a b' b m a0 #
MMonad (Proxy a' a b' b) Source #
Instance details Defined in Pipes.Internal Methods embed :: forall (n :: Type -> Type) m b0. Monad n => (forall a0. m a0 -> Proxy a' a b' b n a0) -> Proxy a' a b' b m b0 -> Proxy a' a b' b n b0 Source #
MonadTrans (Proxy a' a b' b) Source #
Instance details Defined in Pipes.Internal Methods lift :: Monad m => m a0 -> Proxy a' a b' b m a0 #
MonadFail m => MonadFail (Proxy a' a b' b m) Source #
Instance details Defined in Pipes.Internal Methods fail :: String -> Proxy a' a b' b m a0 #
MonadIO m => MonadIO (Proxy a' a b' b m) Source #
Instance details Defined in Pipes.Internal Methods liftIO :: IO a0 -> Proxy a' a b' b m a0 #
Functor m => Applicative (Proxy a' a b' b m) Source #
Instance details Defined in Pipes.Internal Methods pure :: a0 -> Proxy a' a b' b m a0 # (<>) :: Proxy a' a b' b m (a0 -> b0) -> Proxy a' a b' b m a0 -> Proxy a' a b' b m b0 # liftA2 :: (a0 -> b0 -> c) -> Proxy a' a b' b m a0 -> Proxy a' a b' b m b0 -> Proxy a' a b' b m c # (>) :: Proxy a' a b' b m a0 -> Proxy a' a b' b m b0 -> Proxy a' a b' b m b0 # (<*) :: Proxy a' a b' b m a0 -> Proxy a' a b' b m b0 -> Proxy a' a b' b m a0 #
Functor m => Functor (Proxy a' a b' b m) Source #
Instance details Defined in Pipes.Internal Methods fmap :: (a0 -> b0) -> Proxy a' a b' b m a0 -> Proxy a' a b' b m b0 # (<$) :: a0 -> Proxy a' a b' b m b0 -> Proxy a' a b' b m a0 #
Functor m => Monad (Proxy a' a b' b m) Source #
Instance details Defined in Pipes.Internal Methods (>>=) :: Proxy a' a b' b m a0 -> (a0 -> Proxy a' a b' b m b0) -> Proxy a' a b' b m b0 # (>>) :: Proxy a' a b' b m a0 -> Proxy a' a b' b m b0 -> Proxy a' a b' b m b0 # return :: a0 -> Proxy a' a b' b m a0 #
MonadCatch m => MonadCatch (Proxy a' a b' b m) Source #
Instance details Defined in Pipes.Internal Methods catch :: (HasCallStack, Exception e) => Proxy a' a b' b m a0 -> (e -> Proxy a' a b' b m a0) -> Proxy a' a b' b m a0 #
MonadThrow m => MonadThrow (Proxy a' a b' b m) Source #
Instance details Defined in Pipes.Internal Methods throwM :: (HasCallStack, Exception e) => e -> Proxy a' a b' b m a0 #
(Functor m, Monoid r, Semigroup r) => Monoid (Proxy a' a b' b m r) Source #
Instance details Defined in Pipes.Internal Methods mempty :: Proxy a' a b' b m r # mappend :: Proxy a' a b' b m r -> Proxy a' a b' b m r -> Proxy a' a b' b m r # mconcat :: [Proxy a' a b' b m r] -> Proxy a' a b' b m r #
(Functor m, Semigroup r) => Semigroup (Proxy a' a b' b m r) Source #
Instance details Defined in Pipes.Internal Methods (<>) :: Proxy a' a b' b m r -> Proxy a' a b' b m r -> Proxy a' a b' b m r # sconcat :: NonEmpty (Proxy a' a b' b m r) -> Proxy a' a b' b m r # stimes :: Integral b0 => b0 -> Proxy a' a b' b m r -> Proxy a' a b' b m r #

type X = Void Source #

The empty type, used to close output ends

type Effect = Proxy X () () X Source #

An effect in the base monad

Effects neither await nor yield

type Effect' m r = forall x' x y' y. Proxy x' x y' y m r Source #

Like Effect, but with a polymorphic type

runEffect :: Monad m => Effect m r -> m r Source #

Run a self-contained Effect, converting it back to the base monad

Producers

Use yield to produce output and (~>) / for to substitute yields.

yield and (~>) obey the Category laws:

-- Substituting 'yield' with 'f' gives 'f'
yield ~> f = f

-- Substituting every 'yield' with another 'yield' does nothing
f ~> yield = f

-- 'yield' substitution is associative
(f ~> g) ~> h = f ~> (g ~> h)

These are equivalent to the following "for loop laws":

-- Looping over a single yield simplifies to function application
for (yield x) f = f x

-- Re-yielding every element of a stream returns the original stream
for s yield = s

-- Nested for loops can become a sequential for loops if the inner loop
-- body ignores the outer loop variable
for s (\a -> for (f a) g) = for (for s f) g = for s (f ~> g)

type Producer b = Proxy X () () b Source #

Producers can only yield

type Producer' b m r = forall x' x. Proxy x' x () b m r Source #

Like Producer, but with a polymorphic type

yield :: Functor m => a -> Proxy x' x () a m () Source #

Produce a value

yield :: Monad m => a -> Producer a m ()
yield :: Monad m => a -> Pipe   x a m ()

for :: Functor m => Proxy x' x b' b m a' -> (b -> Proxy x' x c' c m b') -> Proxy x' x c' c m a' Source #

(for p body) loops over p replacing each yield with body.

for :: Functor m => Producer b m r -> (b -> Effect       m ()) -> Effect       m r
for :: Functor m => Producer b m r -> (b -> Producer   c m ()) -> Producer   c m r
for :: Functor m => Pipe   x b m r -> (b -> Consumer x   m ()) -> Consumer x   m r
for :: Functor m => Pipe   x b m r -> (b -> Pipe     x c m ()) -> Pipe     x c m r

The following diagrams show the flow of information:

                              .--->   b
                             /        |
   +-----------+            /   +-----|-----+                 +---------------+
   |           |           /    |     v     |                 |               |
   |           |          /     |           |                 |               |
x ==>    p    ==> b   ---'   x ==>   body  ==> c     =     x ==> for p body  ==> c
   |           |                |           |                 |               |
   |     |     |                |     |     |                 |       |       |
   +-----|-----+                +-----|-----+                 +-------|-------+
         v                            v                               v
         r                            ()                              r

For a more complete diagram including bidirectional flow, see Pipes.Core.

(~>) :: Functor m => (a -> Proxy x' x b' b m a') -> (b -> Proxy x' x c' c m b') -> a -> Proxy x' x c' c m a' infixr 4 Source #

Compose loop bodies

(~>) :: Functor m => (a -> Producer b m r) -> (b -> Effect       m ()) -> (a -> Effect       m r)
(~>) :: Functor m => (a -> Producer b m r) -> (b -> Producer   c m ()) -> (a -> Producer   c m r)
(~>) :: Functor m => (a -> Pipe   x b m r) -> (b -> Consumer x   m ()) -> (a -> Consumer x   m r)
(~>) :: Functor m => (a -> Pipe   x b m r) -> (b -> Pipe     x c m ()) -> (a -> Pipe     x c m r)

The following diagrams show the flow of information:

         a                    .--->   b                              a
         |                   /        |                              |
   +-----|-----+            /   +-----|-----+                 +------|------+
   |     v     |           /    |     v     |                 |      v      |
   |           |          /     |           |                 |             |
x ==>    f    ==> b   ---'   x ==>    g    ==> c     =     x ==>   f ~> g  ==> c
   |           |                |           |                 |             |
   |     |     |                |     |     |                 |      |      |
   +-----|-----+                +-----|-----+                 +------|------+
         v                            v                              v
         r                            ()                             r

For a more complete diagram including bidirectional flow, see Pipes.Core.

(<~) :: Functor m => (b -> Proxy x' x c' c m b') -> (a -> Proxy x' x b' b m a') -> a -> Proxy x' x c' c m a' infixl 4 Source #

(~>) with the arguments flipped

Consumers

Use await to request input and (>~) to substitute awaits.

await and (>~) obey the Category laws:

-- Substituting every 'await' with another 'await' does nothing
await >~ f = f

-- Substituting 'await' with 'f' gives 'f'
f >~ await = f

-- 'await' substitution is associative
(f >~ g) >~ h = f >~ (g >~ h)

type Consumer a = Proxy () a () X Source #

Consumers can only await

type Consumer' a m r = forall y' y. Proxy () a y' y m r Source #

Like Consumer, but with a polymorphic type

await :: Functor m => Consumer' a m a Source #

Consume a value

await :: Functor m => Pipe a y m a

(>~) :: Functor m => Proxy a' a y' y m b -> Proxy () b y' y m c -> Proxy a' a y' y m c infixr 5 Source #

(draw >~ p) loops over p replacing each await with draw

(>~) :: Functor m => Effect       m b -> Consumer b   m c -> Effect       m c
(>~) :: Functor m => Consumer a   m b -> Consumer b   m c -> Consumer a   m c
(>~) :: Functor m => Producer   y m b -> Pipe     b y m c -> Producer   y m c
(>~) :: Functor m => Pipe     a y m b -> Pipe     b y m c -> Pipe     a y m c

The following diagrams show the flow of information:

   +-----------+                 +-----------+                 +-------------+
   |           |                 |           |                 |             |
   |           |                 |           |                 |             |
a ==>    f    ==> y   .--->   b ==>    g    ==> y     =     a ==>   f >~ g  ==> y
   |           |     /           |           |                 |             |
   |     |     |    /            |     |     |                 |      |      |
   +-----|-----+   /             +-----|-----+                 +------|------+
         v        /                    v                              v
         b   ----'                     c                              c

For a more complete diagram including bidirectional flow, see Pipes.Core.

(~<) :: Functor m => Proxy () b y' y m c -> Proxy a' a y' y m b -> Proxy a' a y' y m c infixl 5 Source #

(>~) with the arguments flipped

Pipes

Use await and yield to build Pipes and (>->) to connect Pipes.

cat and (>->) obey the Category laws:

-- Useless use of cat
cat >-> f = f

-- Redirecting output to cat does nothing
f >-> cat = f

-- The pipe operator is associative
(f >-> g) >-> h = f >-> (g >-> h)

type Pipe a b = Proxy () a () b Source #

Pipes can both await and yield

cat :: Functor m => Pipe a a m r Source #

The identity Pipe, analogous to the Unix cat program

(>->) :: Functor m => Proxy a' a () b m r -> Proxy () b c' c m r -> Proxy a' a c' c m r infixl 7 Source #

Pipe composition, analogous to the Unix pipe operator

(>->) :: Functor m => Producer b m r -> Consumer b   m r -> Effect       m r
(>->) :: Functor m => Producer b m r -> Pipe     b c m r -> Producer   c m r
(>->) :: Functor m => Pipe   a b m r -> Consumer b   m r -> Consumer a   m r
(>->) :: Functor m => Pipe   a b m r -> Pipe     b c m r -> Pipe     a c m r

The following diagrams show the flow of information:

   +-----------+     +-----------+                 +-------------+
   |           |     |           |                 |             |
   |           |     |           |                 |             |
a ==>    f    ==> b ==>    g    ==> c     =     a ==>  f >-> g  ==> c
   |           |     |           |                 |             |
   |     |     |     |     |     |                 |      |      |
   +-----|-----+     +-----|-----+                 +------|------+
         v                 v                              v
         r                 r                              r

For a more complete diagram including bidirectional flow, see Pipes.Core.

(<-<) :: Functor m => Proxy () b c' c m r -> Proxy a' a () b m r -> Proxy a' a c' c m r infixr 7 Source #

(>->) with the arguments flipped

ListT

newtype ListT m a Source #

The list monad transformer, which extends a monad with non-determinism

The type variables signify:

m - The base monad
a - The values that the computation yields throughout its execution

For basic construction and composition of ListT computations, much can be accomplished using common typeclass methods.

return corresponds to yield, yielding a single value.
(>>=) corresponds to for, calling the second computation once for each time the first computation yields.
mempty neither yields any values nor produces any effects in the base monad.
(<>) sequences two computations, yielding all the values of the first followed by all the values of the second.
lift converts an action in the base monad into a ListT computation which performs the action and yields a single value.

ListT is a newtype wrapper for Producer. You will likely need to use Select and enumerate to convert back and forth between these two types to take advantage of all the Producer-related utilities that Pipes.Prelude has to offer.

To lift a plain list into a ListT computation, first apply each to turn the list into a Producer. Then apply the Select constructor to convert from Producer to ListT.
For other ways to construct ListT computations, see the “Producers” section in Pipes.Prelude to build Producers. These can then be converted to ListT using Select.
To aggregate the values from a ListT computation (for example, to compute the sum of a ListT of numbers), first apply enumerate to obtain a Producer. Then see the “Folds” section in Pipes.Prelude to proceed.

Constructors

Select
Fields enumerate :: Producer a m ()

Instances

Instances details

MMonad ListT Source #
Instance details Defined in Pipes Methods embed :: forall (n :: Type -> Type) m b. Monad n => (forall a. m a -> ListT n a) -> ListT m b -> ListT n b Source #
Enumerable ListT Source #
Instance details Defined in Pipes Methods toListT :: forall (m :: Type -> Type) a. Monad m => ListT m a -> ListT m a Source #
MonadTrans ListT Source #
Instance details Defined in Pipes Methods lift :: Monad m => m a -> ListT m a #
MFunctor ListT Source #
Instance details Defined in Pipes Methods hoist :: forall m n (b :: k). Monad m => (forall a. m a -> n a) -> ListT m b -> ListT n b Source #
MonadError e m => MonadError e (ListT m) Source #
Instance details Defined in Pipes Methods throwError :: e -> ListT m a # catchError :: ListT m a -> (e -> ListT m a) -> ListT m a #
MonadReader i m => MonadReader i (ListT m) Source #
Instance details Defined in Pipes Methods ask :: ListT m i # local :: (i -> i) -> ListT m a -> ListT m a # reader :: (i -> a) -> ListT m a #
MonadState s m => MonadState s (ListT m) Source #
Instance details Defined in Pipes Methods get :: ListT m s # put :: s -> ListT m () # state :: (s -> (a, s)) -> ListT m a #
MonadWriter w m => MonadWriter w (ListT m) Source #
Instance details Defined in Pipes Methods writer :: (a, w) -> ListT m a # tell :: w -> ListT m () # listen :: ListT m a -> ListT m (a, w) # pass :: ListT m (a, w -> w) -> ListT m a #
Monad m => MonadFail (ListT m) Source #
Instance details Defined in Pipes Methods fail :: String -> ListT m a #
MonadIO m => MonadIO (ListT m) Source #
Instance details Defined in Pipes Methods liftIO :: IO a -> ListT m a #
Monad m => MonadZip (ListT m) Source #
Instance details Defined in Pipes Methods mzip :: ListT m a -> ListT m b -> ListT m (a, b) # mzipWith :: (a -> b -> c) -> ListT m a -> ListT m b -> ListT m c # munzip :: ListT m (a, b) -> (ListT m a, ListT m b) #
Foldable m => Foldable (ListT m) Source #
Instance details Defined in Pipes Methods fold :: Monoid m0 => ListT m m0 -> m0 # foldMap :: Monoid m0 => (a -> m0) -> ListT m a -> m0 # foldMap' :: Monoid m0 => (a -> m0) -> ListT m a -> m0 # foldr :: (a -> b -> b) -> b -> ListT m a -> b # foldr' :: (a -> b -> b) -> b -> ListT m a -> b # foldl :: (b -> a -> b) -> b -> ListT m a -> b # foldl' :: (b -> a -> b) -> b -> ListT m a -> b # foldr1 :: (a -> a -> a) -> ListT m a -> a # foldl1 :: (a -> a -> a) -> ListT m a -> a # toList :: ListT m a -> [a] # null :: ListT m a -> Bool # length :: ListT m a -> Int # elem :: Eq a => a -> ListT m a -> Bool # maximum :: Ord a => ListT m a -> a # minimum :: Ord a => ListT m a -> a # sum :: Num a => ListT m a -> a # product :: Num a => ListT m a -> a #
(Functor m, Traversable m) => Traversable (ListT m) Source #
Instance details Defined in Pipes Methods traverse :: Applicative f => (a -> f b) -> ListT m a -> f (ListT m b) # sequenceA :: Applicative f => ListT m (f a) -> f (ListT m a) # mapM :: Monad m0 => (a -> m0 b) -> ListT m a -> m0 (ListT m b) # sequence :: Monad m0 => ListT m (m0 a) -> m0 (ListT m a) #
Functor m => Alternative (ListT m) Source #
Instance details Defined in Pipes Methods empty :: ListT m a # (<\|>) :: ListT m a -> ListT m a -> ListT m a # some :: ListT m a -> ListT m [a] # many :: ListT m a -> ListT m [a] #
Functor m => Applicative (ListT m) Source #
Instance details Defined in Pipes Methods pure :: a -> ListT m a # (<>) :: ListT m (a -> b) -> ListT m a -> ListT m b # liftA2 :: (a -> b -> c) -> ListT m a -> ListT m b -> ListT m c # (>) :: ListT m a -> ListT m b -> ListT m b # (<*) :: ListT m a -> ListT m b -> ListT m a #
Functor m => Functor (ListT m) Source #
Instance details Defined in Pipes Methods fmap :: (a -> b) -> ListT m a -> ListT m b # (<$) :: a -> ListT m b -> ListT m a #
Monad m => Monad (ListT m) Source #
Instance details Defined in Pipes Methods (>>=) :: ListT m a -> (a -> ListT m b) -> ListT m b # (>>) :: ListT m a -> ListT m b -> ListT m b # return :: a -> ListT m a #
Monad m => MonadPlus (ListT m) Source #
Instance details Defined in Pipes Methods mzero :: ListT m a # mplus :: ListT m a -> ListT m a -> ListT m a #
MonadCatch m => MonadCatch (ListT m) Source #
Instance details Defined in Pipes Methods catch :: (HasCallStack, Exception e) => ListT m a -> (e -> ListT m a) -> ListT m a #
MonadThrow m => MonadThrow (ListT m) Source #
Instance details Defined in Pipes Methods throwM :: (HasCallStack, Exception e) => e -> ListT m a #
Functor m => Monoid (ListT m a) Source #
Instance details Defined in Pipes Methods mempty :: ListT m a # mappend :: ListT m a -> ListT m a -> ListT m a # mconcat :: [ListT m a] -> ListT m a #
Functor m => Semigroup (ListT m a) Source #
Instance details Defined in Pipes Methods (<>) :: ListT m a -> ListT m a -> ListT m a # sconcat :: NonEmpty (ListT m a) -> ListT m a # stimes :: Integral b => b -> ListT m a -> ListT m a #

runListT :: Monad m => ListT m a -> m () Source #

Run a self-contained ListT computation

class Enumerable t where Source #

Enumerable generalizes Foldable, converting effectful containers to ListTs.

Instances of Enumerable must satisfy these two laws:

toListT (return r) = return r

toListT $ do x <- m  =  do x <- toListT m
             f x           toListT (f x)

In other words, toListT is monad morphism.

Methods

toListT :: Monad m => t m a -> ListT m a Source #

Instances

Instances details

Enumerable ListT Source #
Instance details Defined in Pipes Methods toListT :: forall (m :: Type -> Type) a. Monad m => ListT m a -> ListT m a Source #
Enumerable MaybeT Source #
Instance details Defined in Pipes Methods toListT :: forall (m :: Type -> Type) a. Monad m => MaybeT m a -> ListT m a Source #
Enumerable (ExceptT e) Source #
Instance details Defined in Pipes Methods toListT :: forall (m :: Type -> Type) a. Monad m => ExceptT e m a -> ListT m a Source #
Enumerable (IdentityT :: (Type -> Type) -> Type -> Type) Source #
Instance details Defined in Pipes Methods toListT :: forall (m :: Type -> Type) a. Monad m => IdentityT m a -> ListT m a Source #

Utilities

next :: Monad m => Producer a m r -> m (Either r (a, Producer a m r)) Source #

Consume the first value from a Producer

next either fails with a Left if the Producer terminates or succeeds with a Right providing the next value and the remainder of the Producer.

each :: (Functor m, Foldable f) => f a -> Proxy x' x () a m () Source #

Convert a Foldable to a Producer

each :: (Functor m, Foldable f) => f a -> Producer a m ()

every :: (Monad m, Enumerable t) => t m a -> Proxy x' x () a m () Source #

Convert an Enumerable to a Producer

every :: (Monad m, Enumerable t) => t m a -> Producer a m ()

discard :: Monad m => a -> m () Source #

Discards a value

Re-exports

Control.Monad re-exports void

Control.Monad.IO.Class re-exports MonadIO.

Control.Monad.Trans.Class re-exports MonadTrans.

Control.Monad.Morph re-exports MFunctor.

Data.Foldable re-exports Foldable (the class name only).

class (Alternative m, Monad m) => MonadPlus (m :: Type -> Type) where #

Monads that also support choice and failure.

Minimal complete definition

Nothing

Methods

mzero :: m a #

The identity of mplus. It should also satisfy the equations

mzero >>= f  =  mzero
v >> mzero   =  mzero

The default definition is

mzero = empty

mplus :: m a -> m a -> m a #

An associative operation. The default definition is

mplus = (<|>)

Instances

Instances details

MonadPlus STM	Takes the first non-`retry`ing `STM` action. Since: base-4.3.0.0
Instance details Defined in GHC.Conc.Sync Methods mzero :: STM a # mplus :: STM a -> STM a -> STM a #
MonadPlus P	Since: base-2.1
Instance details Defined in Text.ParserCombinators.ReadP Methods mzero :: P a # mplus :: P a -> P a -> P a #
MonadPlus ReadP	Since: base-2.1
Instance details Defined in Text.ParserCombinators.ReadP Methods mzero :: ReadP a # mplus :: ReadP a -> ReadP a -> ReadP a #
MonadPlus IO	Takes the first non-throwing `IO` action's result. `mzero` throws an exception. Since: base-4.9.0.0
Instance details Defined in GHC.Base Methods mzero :: IO a # mplus :: IO a -> IO a -> IO a #
MonadPlus Maybe	Picks the leftmost `Just` value, or, alternatively, `Nothing`. Since: base-2.1
Instance details Defined in GHC.Base Methods mzero :: Maybe a # mplus :: Maybe a -> Maybe a -> Maybe a #
MonadPlus List	Combines lists by concatenation, starting from the empty list. Since: base-2.1
Instance details Defined in GHC.Base Methods mzero :: [a] # mplus :: [a] -> [a] -> [a] #
(ArrowApply a, ArrowPlus a) => MonadPlus (ArrowMonad a)	Since: base-4.6.0.0
Instance details Defined in Control.Arrow Methods mzero :: ArrowMonad a a0 # mplus :: ArrowMonad a a0 -> ArrowMonad a a0 -> ArrowMonad a a0 #
MonadPlus (U1 :: Type -> Type)	Since: base-4.9.0.0
Instance details Defined in GHC.Generics Methods mzero :: U1 a # mplus :: U1 a -> U1 a -> U1 a #
Monad m => MonadPlus (ListT m) Source #
Instance details Defined in Pipes Methods mzero :: ListT m a # mplus :: ListT m a -> ListT m a -> ListT m a #
Monad m => MonadPlus (MaybeT m)
Instance details Defined in Control.Monad.Trans.Maybe Methods mzero :: MaybeT m a # mplus :: MaybeT m a -> MaybeT m a -> MaybeT m a #
MonadPlus m => MonadPlus (Kleisli m a)	Since: base-4.14.0.0
Instance details Defined in Control.Arrow Methods mzero :: Kleisli m a a0 # mplus :: Kleisli m a a0 -> Kleisli m a a0 -> Kleisli m a a0 #
MonadPlus f => MonadPlus (Alt f)	Since: base-4.8.0.0
Instance details Defined in Data.Semigroup.Internal Methods mzero :: Alt f a # mplus :: Alt f a -> Alt f a -> Alt f a #
MonadPlus f => MonadPlus (Rec1 f)	Since: base-4.9.0.0
Instance details Defined in GHC.Generics Methods mzero :: Rec1 f a # mplus :: Rec1 f a -> Rec1 f a -> Rec1 f a #
(Monoid w, Functor m, MonadPlus m) => MonadPlus (AccumT w m)
Instance details Defined in Control.Monad.Trans.Accum Methods mzero :: AccumT w m a # mplus :: AccumT w m a -> AccumT w m a -> AccumT w m a #
(Monad m, Monoid e) => MonadPlus (ExceptT e m)
Instance details Defined in Control.Monad.Trans.Except Methods mzero :: ExceptT e m a # mplus :: ExceptT e m a -> ExceptT e m a -> ExceptT e m a #
MonadPlus m => MonadPlus (IdentityT m)
Instance details Defined in Control.Monad.Trans.Identity Methods mzero :: IdentityT m a # mplus :: IdentityT m a -> IdentityT m a -> IdentityT m a #
MonadPlus m => MonadPlus (ReaderT r m)
Instance details Defined in Control.Monad.Trans.Reader Methods mzero :: ReaderT r m a # mplus :: ReaderT r m a -> ReaderT r m a -> ReaderT r m a #
MonadPlus m => MonadPlus (SelectT r m)
Instance details Defined in Control.Monad.Trans.Select Methods mzero :: SelectT r m a # mplus :: SelectT r m a -> SelectT r m a -> SelectT r m a #
MonadPlus m => MonadPlus (StateT s m)
Instance details Defined in Control.Monad.Trans.State.Lazy Methods mzero :: StateT s m a # mplus :: StateT s m a -> StateT s m a -> StateT s m a #
MonadPlus m => MonadPlus (StateT s m)
Instance details Defined in Control.Monad.Trans.State.Strict Methods mzero :: StateT s m a # mplus :: StateT s m a -> StateT s m a -> StateT s m a #
(Functor m, MonadPlus m) => MonadPlus (WriterT w m)
Instance details Defined in Control.Monad.Trans.Writer.CPS Methods mzero :: WriterT w m a # mplus :: WriterT w m a -> WriterT w m a -> WriterT w m a #
(Monoid w, MonadPlus m) => MonadPlus (WriterT w m)
Instance details Defined in Control.Monad.Trans.Writer.Lazy Methods mzero :: WriterT w m a # mplus :: WriterT w m a -> WriterT w m a -> WriterT w m a #
(Monoid w, MonadPlus m) => MonadPlus (WriterT w m)
Instance details Defined in Control.Monad.Trans.Writer.Strict Methods mzero :: WriterT w m a # mplus :: WriterT w m a -> WriterT w m a -> WriterT w m a #
(MonadPlus f, MonadPlus g) => MonadPlus (f :*: g)	Since: base-4.9.0.0
Instance details Defined in GHC.Generics Methods mzero :: (f :: g) a # mplus :: (f :: g) a -> (f :: g) a -> (f :: g) a #
MonadPlus f => MonadPlus (M1 i c f)	Since: base-4.9.0.0
Instance details Defined in GHC.Generics Methods mzero :: M1 i c f a # mplus :: M1 i c f a -> M1 i c f a -> M1 i c f a #
(Functor m, MonadPlus m) => MonadPlus (RWST r w s m)
Instance details Defined in Control.Monad.Trans.RWS.CPS Methods mzero :: RWST r w s m a # mplus :: RWST r w s m a -> RWST r w s m a -> RWST r w s m a #
(Monoid w, MonadPlus m) => MonadPlus (RWST r w s m)
Instance details Defined in Control.Monad.Trans.RWS.Lazy Methods mzero :: RWST r w s m a # mplus :: RWST r w s m a -> RWST r w s m a -> RWST r w s m a #
(Monoid w, MonadPlus m) => MonadPlus (RWST r w s m)
Instance details Defined in Control.Monad.Trans.RWS.Strict Methods mzero :: RWST r w s m a # mplus :: RWST r w s m a -> RWST r w s m a -> RWST r w s m a #

void :: Functor f => f a -> f () #

void value discards or ignores the result of evaluation, such as the return value of an IO action.

Examples

Expand

Replace the contents of a Maybe Int with unit:

>>> void Nothing
Nothing
>>> void (Just 3)
Just ()

Replace the contents of an Either Int Int with unit, resulting in an Either Int ():

>>> void (Left 8675309)
Left 8675309
>>> void (Right 8675309)
Right ()

Replace every element of a list with unit:

>>> void [1,2,3]
[(),(),()]

Replace the second element of a pair with unit:

>>> void (1,2)
(1,())

Discard the result of an IO action:

>>> mapM print [1,2]
1
2
[(),()]
>>> void $ mapM print [1,2]
1
2

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. 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 IO	Since: base-4.9.0.0
Instance details Defined in Control.Monad.IO.Class Methods liftIO :: IO a -> IO a #
MonadIO Q
Instance details Defined in Language.Haskell.TH.Syntax Methods liftIO :: IO a -> Q a #
MonadIO m => MonadIO (ListT m) Source #
Instance details Defined in Pipes Methods liftIO :: IO a -> ListT m a #
MonadIO m => MonadIO (MaybeT m)
Instance details Defined in Control.Monad.Trans.Maybe Methods liftIO :: IO a -> MaybeT m a #
(Monoid w, Functor m, MonadIO m) => MonadIO (AccumT w m)
Instance details Defined in Control.Monad.Trans.Accum Methods liftIO :: IO a -> AccumT w m a #
MonadIO m => MonadIO (ExceptT e m)
Instance details Defined in Control.Monad.Trans.Except Methods liftIO :: IO a -> ExceptT e m a #
MonadIO m => MonadIO (IdentityT m)
Instance details Defined in Control.Monad.Trans.Identity Methods liftIO :: IO a -> IdentityT m a #
MonadIO m => MonadIO (ReaderT r m)
Instance details Defined in Control.Monad.Trans.Reader Methods liftIO :: IO a -> ReaderT r m a #
MonadIO m => MonadIO (SelectT r m)
Instance details Defined in Control.Monad.Trans.Select Methods liftIO :: IO a -> SelectT r m a #
MonadIO m => MonadIO (StateT s m)
Instance details Defined in Control.Monad.Trans.State.Lazy Methods liftIO :: IO a -> StateT s m a #
MonadIO m => MonadIO (StateT s m)
Instance details Defined in Control.Monad.Trans.State.Strict Methods liftIO :: IO a -> StateT s m a #
MonadIO m => MonadIO (WriterT w m)
Instance details Defined in Control.Monad.Trans.Writer.CPS Methods liftIO :: IO a -> WriterT w m a #
(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 #
(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 #
MonadIO m => MonadIO (ContT r m)
Instance details Defined in Control.Monad.Trans.Cont Methods liftIO :: IO a -> ContT r m a #
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 #
(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 #
(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 #
MonadIO m => MonadIO (Proxy a' a b' b m) Source #
Instance details Defined in Pipes.Internal Methods liftIO :: IO a0 -> Proxy a' a b' b m a0 #

class (forall (m :: Type -> Type). Monad m => Monad (t m)) => MonadTrans (t :: (Type -> Type) -> Type -> Type) where #

The class of monad transformers. For any monad m, the result t m should also be a monad, and lift should be a monad transformation from m to t m, i.e. it should satisfy the following laws:

```
lift . return = return
```
```
lift (m >>= f) = lift m >>= (lift . f)
```

Since 0.6.0.0 and for GHC 8.6 and later, the requirement that t m be a Monad is enforced by the implication constraint forall m. Monad m => Monad (t m) enabled by the QuantifiedConstraints extension.

Ambiguity error with GHC 9.0 to 9.2.2

Expand

These versions of GHC have a bug (https://gitlab.haskell.org/ghc/ghc/-/issues/20582) which causes constraints like

(MonadTrans t, forall m. Monad m => Monad (t m)) => ...

to be reported as ambiguous. For transformers 0.6 and later, this can be fixed by removing the second constraint, which is implied by the first.

Methods

lift :: Monad m => m a -> t m a #

Lift a computation from the argument monad to the constructed monad.

Instances

Instances details

MonadTrans ListT Source #
Instance details Defined in Pipes Methods lift :: Monad m => m a -> ListT m a #
MonadTrans MaybeT
Instance details Defined in Control.Monad.Trans.Maybe Methods lift :: Monad m => m a -> MaybeT m a #
Monoid w => MonadTrans (AccumT w)
Instance details Defined in Control.Monad.Trans.Accum Methods lift :: Monad m => m a -> AccumT w m a #
MonadTrans (ExceptT e)
Instance details Defined in Control.Monad.Trans.Except Methods lift :: Monad m => m a -> ExceptT e m a #
MonadTrans (IdentityT :: (Type -> Type) -> Type -> Type)
Instance details Defined in Control.Monad.Trans.Identity Methods lift :: Monad m => m a -> IdentityT m a #
MonadTrans (ReaderT r)
Instance details Defined in Control.Monad.Trans.Reader Methods lift :: Monad m => m a -> ReaderT r m a #
MonadTrans (SelectT r)
Instance details Defined in Control.Monad.Trans.Select Methods lift :: Monad m => m a -> SelectT r m a #
MonadTrans (StateT s)
Instance details Defined in Control.Monad.Trans.State.Lazy Methods lift :: Monad m => m a -> StateT s m a #
MonadTrans (StateT s)
Instance details Defined in Control.Monad.Trans.State.Strict Methods lift :: Monad m => m a -> StateT s m a #
MonadTrans (WriterT w)
Instance details Defined in Control.Monad.Trans.Writer.CPS Methods lift :: Monad m => m a -> WriterT w m a #
Monoid w => MonadTrans (WriterT w)
Instance details Defined in Control.Monad.Trans.Writer.Lazy Methods lift :: Monad m => m a -> WriterT w m a #
Monoid w => MonadTrans (WriterT w)
Instance details Defined in Control.Monad.Trans.Writer.Strict Methods lift :: Monad m => m a -> WriterT w m a #
MonadTrans (ContT r)
Instance details Defined in Control.Monad.Trans.Cont Methods lift :: Monad m => m a -> ContT r m a #
MonadTrans (RWST r w s)
Instance details Defined in Control.Monad.Trans.RWS.CPS Methods lift :: Monad m => m a -> RWST r w s m a #
Monoid w => MonadTrans (RWST r w s)
Instance details Defined in Control.Monad.Trans.RWS.Lazy Methods lift :: Monad m => m a -> RWST r w s m a #
Monoid w => MonadTrans (RWST r w s)
Instance details Defined in Control.Monad.Trans.RWS.Strict Methods lift :: Monad m => m a -> RWST r w s m a #
MonadTrans (Proxy a' a b' b) Source #
Instance details Defined in Pipes.Internal Methods lift :: Monad m => m a0 -> Proxy a' a b' b m a0 #

class (MFunctor t, MonadTrans t) => MMonad (t :: (Type -> Type) -> Type -> Type) where Source #

A monad in the category of monads, using lift from MonadTrans as the analog of return and embed as the analog of (=<<):

embed lift = id

embed f (lift m) = f m

embed g (embed f t) = embed (\m -> embed g (f m)) t

Methods

embed :: forall (n :: Type -> Type) m b. Monad n => (forall a. m a -> t n a) -> t m b -> t n b Source #

Embed a newly created MMonad layer within an existing layer

embed is analogous to (=<<)

Instances

Instances details

MMonad ListT Source #
Instance details Defined in Pipes Methods embed :: forall (n :: Type -> Type) m b. Monad n => (forall a. m a -> ListT n a) -> ListT m b -> ListT n b Source #
MMonad MaybeT
Instance details Defined in Control.Monad.Morph Methods embed :: forall (n :: Type -> Type) m b. Monad n => (forall a. m a -> MaybeT n a) -> MaybeT m b -> MaybeT n b Source #
MMonad (ExceptT e)
Instance details Defined in Control.Monad.Morph Methods embed :: forall (n :: Type -> Type) m b. Monad n => (forall a. m a -> ExceptT e n a) -> ExceptT e m b -> ExceptT e n b Source #
MMonad (IdentityT :: (Type -> Type) -> Type -> Type)
Instance details Defined in Control.Monad.Morph Methods embed :: forall (n :: Type -> Type) m b. Monad n => (forall a. m a -> IdentityT n a) -> IdentityT m b -> IdentityT n b Source #
MMonad (ReaderT r)
Instance details Defined in Control.Monad.Morph Methods embed :: forall (n :: Type -> Type) m b. Monad n => (forall a. m a -> ReaderT r n a) -> ReaderT r m b -> ReaderT r n b Source #
Monoid w => MMonad (WriterT w)
Instance details Defined in Control.Monad.Morph Methods embed :: forall (n :: Type -> Type) m b. Monad n => (forall a. m a -> WriterT w n a) -> WriterT w m b -> WriterT w n b Source #
Monoid w => MMonad (WriterT w)
Instance details Defined in Control.Monad.Morph Methods embed :: forall (n :: Type -> Type) m b. Monad n => (forall a. m a -> WriterT w n a) -> WriterT w m b -> WriterT w n b Source #
MMonad (Proxy a' a b' b) Source #
Instance details Defined in Pipes.Internal Methods embed :: forall (n :: Type -> Type) m b0. Monad n => (forall a0. m a0 -> Proxy a' a b' b n a0) -> Proxy a' a b' b m b0 -> Proxy a' a b' b n b0 Source #

class MFunctor (t :: (Type -> Type) -> k -> Type) where Source #

A functor in the category of monads, using hoist as the analog of fmap:

hoist (f . g) = hoist f . hoist g

hoist id = id

Methods

hoist :: forall m n (b :: k). Monad m => (forall a. m a -> n a) -> t m b -> t n b Source #

Lift a monad morphism from m to n into a monad morphism from (t m) to (t n)

The first argument to hoist must be a monad morphism, even though the type system does not enforce this

Instances

Instances details

MFunctor ListT Source #
Instance details Defined in Pipes Methods hoist :: forall m n (b :: k). Monad m => (forall a. m a -> n a) -> ListT m b -> ListT n b Source #
MFunctor Lift
Instance details Defined in Control.Monad.Morph Methods hoist :: forall m n (b :: k). Monad m => (forall a. m a -> n a) -> Lift m b -> Lift n b Source #
MFunctor MaybeT
Instance details Defined in Control.Monad.Morph Methods hoist :: forall m n (b :: k). Monad m => (forall a. m a -> n a) -> MaybeT m b -> MaybeT n b Source #
MFunctor (Backwards :: (Type -> Type) -> Type -> Type)
Instance details Defined in Control.Monad.Morph Methods hoist :: forall m n (b :: k). Monad m => (forall a. m a -> n a) -> Backwards m b -> Backwards n b Source #
MFunctor (ExceptT e :: (Type -> Type) -> Type -> Type)
Instance details Defined in Control.Monad.Morph Methods hoist :: forall m n (b :: k). Monad m => (forall a. m a -> n a) -> ExceptT e m b -> ExceptT e n b Source #
MFunctor (IdentityT :: (Type -> Type) -> Type -> Type)
Instance details Defined in Control.Monad.Morph Methods hoist :: forall m n (b :: k). Monad m => (forall a. m a -> n a) -> IdentityT m b -> IdentityT n b Source #
MFunctor (ReaderT r :: (Type -> Type) -> Type -> Type)
Instance details Defined in Control.Monad.Morph Methods hoist :: forall m n (b :: k). Monad m => (forall a. m a -> n a) -> ReaderT r m b -> ReaderT r n b Source #
MFunctor (StateT s :: (Type -> Type) -> Type -> Type)
Instance details Defined in Control.Monad.Morph Methods hoist :: forall m n (b :: k). Monad m => (forall a. m a -> n a) -> StateT s m b -> StateT s n b Source #
MFunctor (StateT s :: (Type -> Type) -> Type -> Type)
Instance details Defined in Control.Monad.Morph Methods hoist :: forall m n (b :: k). Monad m => (forall a. m a -> n a) -> StateT s m b -> StateT s n b Source #
MFunctor (WriterT w :: (Type -> Type) -> Type -> Type)
Instance details Defined in Control.Monad.Morph Methods hoist :: forall m n (b :: k). Monad m => (forall a. m a -> n a) -> WriterT w m b -> WriterT w n b Source #
MFunctor (WriterT w :: (Type -> Type) -> Type -> Type)
Instance details Defined in Control.Monad.Morph Methods hoist :: forall m n (b :: k). Monad m => (forall a. m a -> n a) -> WriterT w m b -> WriterT w n b Source #
MFunctor (Product f :: (Type -> Type) -> Type -> Type)
Instance details Defined in Control.Monad.Morph Methods hoist :: forall m n (b :: k). Monad m => (forall a. m a -> n a) -> Product f m b -> Product f n b Source #
Functor f => MFunctor (Compose f :: (Type -> Type) -> Type -> Type)
Instance details Defined in Control.Monad.Morph Methods hoist :: forall m n (b :: k). Monad m => (forall a. m a -> n a) -> Compose f m b -> Compose f n b Source #
MFunctor (RWST r w s :: (Type -> Type) -> Type -> Type)
Instance details Defined in Control.Monad.Morph Methods hoist :: forall m n (b :: k). Monad m => (forall a. m a -> n a) -> RWST r w s m b -> RWST r w s n b Source #
MFunctor (RWST r w s :: (Type -> Type) -> Type -> Type)
Instance details Defined in Control.Monad.Morph Methods hoist :: forall m n (b :: k). Monad m => (forall a. m a -> n a) -> RWST r w s m b -> RWST r w s n b Source #
MFunctor (Proxy a' a b' b :: (Type -> Type) -> Type -> Type) Source #
Instance details Defined in Pipes.Internal Methods hoist :: forall m n (b0 :: k). Monad m => (forall a0. m a0 -> n a0) -> Proxy a' a b' b m b0 -> Proxy a' a b' b n b0 Source #

class Foldable (t :: Type -> Type) #

The Foldable class represents data structures that can be reduced to a summary value one element at a time. Strict left-associative folds are a good fit for space-efficient reduction, while lazy right-associative folds are a good fit for corecursive iteration, or for folds that short-circuit after processing an initial subsequence of the structure's elements.

Instances can be derived automatically by enabling the DeriveFoldable extension. For example, a derived instance for a binary tree might be:

{-# LANGUAGE DeriveFoldable #-}
data Tree a = Empty
            | Leaf a
            | Node (Tree a) a (Tree a)
    deriving Foldable

A more detailed description can be found in the Overview section of Data.Foldable.

For the class laws see the Laws section of Data.Foldable.

Minimal complete definition

foldMap | foldr

Instances

Instances details

Foldable ZipList	Since: base-4.9.0.0
Instance details Defined in Control.Applicative Methods fold :: Monoid m => ZipList m -> m # foldMap :: Monoid m => (a -> m) -> ZipList a -> m # foldMap' :: Monoid m => (a -> m) -> ZipList a -> m # foldr :: (a -> b -> b) -> b -> ZipList a -> b # foldr' :: (a -> b -> b) -> b -> ZipList a -> b # foldl :: (b -> a -> b) -> b -> ZipList a -> b # foldl' :: (b -> a -> b) -> b -> ZipList a -> b # foldr1 :: (a -> a -> a) -> ZipList a -> a # foldl1 :: (a -> a -> a) -> ZipList a -> a # toList :: ZipList a -> [a] # null :: ZipList a -> Bool # length :: ZipList a -> Int # elem :: Eq a => a -> ZipList a -> Bool # maximum :: Ord a => ZipList a -> a # minimum :: Ord a => ZipList a -> a # sum :: Num a => ZipList a -> a # product :: Num a => ZipList a -> a #
Foldable Identity	Since: base-4.8.0.0
Instance details Defined in Data.Functor.Identity Methods fold :: Monoid m => Identity m -> m # foldMap :: Monoid m => (a -> m) -> Identity a -> m # foldMap' :: Monoid m => (a -> m) -> Identity a -> m # foldr :: (a -> b -> b) -> b -> Identity a -> b # foldr' :: (a -> b -> b) -> b -> Identity a -> b # foldl :: (b -> a -> b) -> b -> Identity a -> b # foldl' :: (b -> a -> b) -> b -> Identity a -> b # foldr1 :: (a -> a -> a) -> Identity a -> a # foldl1 :: (a -> a -> a) -> Identity a -> a # toList :: Identity a -> [a] # null :: Identity a -> Bool # length :: Identity a -> Int # elem :: Eq a => a -> Identity a -> Bool # maximum :: Ord a => Identity a -> a # minimum :: Ord a => Identity a -> a # sum :: Num a => Identity a -> a # product :: Num a => Identity a -> a #
Foldable First	Since: base-4.8.0.0
Instance details Defined in Data.Foldable Methods fold :: Monoid m => First m -> m # foldMap :: Monoid m => (a -> m) -> First a -> m # foldMap' :: Monoid m => (a -> m) -> First a -> m # foldr :: (a -> b -> b) -> b -> First a -> b # foldr' :: (a -> b -> b) -> b -> First a -> b # foldl :: (b -> a -> b) -> b -> First a -> b # foldl' :: (b -> a -> b) -> b -> First a -> b # foldr1 :: (a -> a -> a) -> First a -> a # foldl1 :: (a -> a -> a) -> First a -> a # toList :: First a -> [a] # null :: First a -> Bool # length :: First a -> Int # elem :: Eq a => a -> First a -> Bool # maximum :: Ord a => First a -> a # minimum :: Ord a => First a -> a # sum :: Num a => First a -> a # product :: Num a => First a -> a #
Foldable Last	Since: base-4.8.0.0
Instance details Defined in Data.Foldable Methods fold :: Monoid m => Last m -> m # foldMap :: Monoid m => (a -> m) -> Last a -> m # foldMap' :: Monoid m => (a -> m) -> Last a -> m # foldr :: (a -> b -> b) -> b -> Last a -> b # foldr' :: (a -> b -> b) -> b -> Last a -> b # foldl :: (b -> a -> b) -> b -> Last a -> b # foldl' :: (b -> a -> b) -> b -> Last a -> b # foldr1 :: (a -> a -> a) -> Last a -> a # foldl1 :: (a -> a -> a) -> Last a -> a # toList :: Last a -> [a] # null :: Last a -> Bool # length :: Last a -> Int # elem :: Eq a => a -> Last a -> Bool # maximum :: Ord a => Last a -> a # minimum :: Ord a => Last a -> a # sum :: Num a => Last a -> a # product :: Num a => Last a -> a #
Foldable Down	Since: base-4.12.0.0
Instance details Defined in Data.Foldable Methods fold :: Monoid m => Down m -> m # foldMap :: Monoid m => (a -> m) -> Down a -> m # foldMap' :: Monoid m => (a -> m) -> Down a -> m # foldr :: (a -> b -> b) -> b -> Down a -> b # foldr' :: (a -> b -> b) -> b -> Down a -> b # foldl :: (b -> a -> b) -> b -> Down a -> b # foldl' :: (b -> a -> b) -> b -> Down a -> b # foldr1 :: (a -> a -> a) -> Down a -> a # foldl1 :: (a -> a -> a) -> Down a -> a # toList :: Down a -> [a] # null :: Down a -> Bool # length :: Down a -> Int # elem :: Eq a => a -> Down a -> Bool # maximum :: Ord a => Down a -> a # minimum :: Ord a => Down a -> a # sum :: Num a => Down a -> a # product :: Num a => Down a -> a #
Foldable First	Since: base-4.9.0.0
Instance details Defined in Data.Semigroup Methods fold :: Monoid m => First m -> m # foldMap :: Monoid m => (a -> m) -> First a -> m # foldMap' :: Monoid m => (a -> m) -> First a -> m # foldr :: (a -> b -> b) -> b -> First a -> b # foldr' :: (a -> b -> b) -> b -> First a -> b # foldl :: (b -> a -> b) -> b -> First a -> b # foldl' :: (b -> a -> b) -> b -> First a -> b # foldr1 :: (a -> a -> a) -> First a -> a # foldl1 :: (a -> a -> a) -> First a -> a # toList :: First a -> [a] # null :: First a -> Bool # length :: First a -> Int # elem :: Eq a => a -> First a -> Bool # maximum :: Ord a => First a -> a # minimum :: Ord a => First a -> a # sum :: Num a => First a -> a # product :: Num a => First a -> a #
Foldable Last	Since: base-4.9.0.0
Instance details Defined in Data.Semigroup Methods fold :: Monoid m => Last m -> m # foldMap :: Monoid m => (a -> m) -> Last a -> m # foldMap' :: Monoid m => (a -> m) -> Last a -> m # foldr :: (a -> b -> b) -> b -> Last a -> b # foldr' :: (a -> b -> b) -> b -> Last a -> b # foldl :: (b -> a -> b) -> b -> Last a -> b # foldl' :: (b -> a -> b) -> b -> Last a -> b # foldr1 :: (a -> a -> a) -> Last a -> a # foldl1 :: (a -> a -> a) -> Last a -> a # toList :: Last a -> [a] # null :: Last a -> Bool # length :: Last a -> Int # elem :: Eq a => a -> Last a -> Bool # maximum :: Ord a => Last a -> a # minimum :: Ord a => Last a -> a # sum :: Num a => Last a -> a # product :: Num a => Last a -> a #
Foldable Max	Since: base-4.9.0.0
Instance details Defined in Data.Semigroup Methods fold :: Monoid m => Max m -> m # foldMap :: Monoid m => (a -> m) -> Max a -> m # foldMap' :: Monoid m => (a -> m) -> Max a -> m # foldr :: (a -> b -> b) -> b -> Max a -> b # foldr' :: (a -> b -> b) -> b -> Max a -> b # foldl :: (b -> a -> b) -> b -> Max a -> b # foldl' :: (b -> a -> b) -> b -> Max a -> b # foldr1 :: (a -> a -> a) -> Max a -> a # foldl1 :: (a -> a -> a) -> Max a -> a # toList :: Max a -> [a] # null :: Max a -> Bool # length :: Max a -> Int # elem :: Eq a => a -> Max a -> Bool # maximum :: Ord a => Max a -> a # minimum :: Ord a => Max a -> a # sum :: Num a => Max a -> a # product :: Num a => Max a -> a #
Foldable Min	Since: base-4.9.0.0
Instance details Defined in Data.Semigroup Methods fold :: Monoid m => Min m -> m # foldMap :: Monoid m => (a -> m) -> Min a -> m # foldMap' :: Monoid m => (a -> m) -> Min a -> m # foldr :: (a -> b -> b) -> b -> Min a -> b # foldr' :: (a -> b -> b) -> b -> Min a -> b # foldl :: (b -> a -> b) -> b -> Min a -> b # foldl' :: (b -> a -> b) -> b -> Min a -> b # foldr1 :: (a -> a -> a) -> Min a -> a # foldl1 :: (a -> a -> a) -> Min a -> a # toList :: Min a -> [a] # null :: Min a -> Bool # length :: Min a -> Int # elem :: Eq a => a -> Min a -> Bool # maximum :: Ord a => Min a -> a # minimum :: Ord a => Min a -> a # sum :: Num a => Min a -> a # product :: Num a => Min a -> a #
Foldable Dual	Since: base-4.8.0.0
Instance details Defined in Data.Foldable Methods fold :: Monoid m => Dual m -> m # foldMap :: Monoid m => (a -> m) -> Dual a -> m # foldMap' :: Monoid m => (a -> m) -> Dual a -> m # foldr :: (a -> b -> b) -> b -> Dual a -> b # foldr' :: (a -> b -> b) -> b -> Dual a -> b # foldl :: (b -> a -> b) -> b -> Dual a -> b # foldl' :: (b -> a -> b) -> b -> Dual a -> b # foldr1 :: (a -> a -> a) -> Dual a -> a # foldl1 :: (a -> a -> a) -> Dual a -> a # toList :: Dual a -> [a] # null :: Dual a -> Bool # length :: Dual a -> Int # elem :: Eq a => a -> Dual a -> Bool # maximum :: Ord a => Dual a -> a # minimum :: Ord a => Dual a -> a # sum :: Num a => Dual a -> a # product :: Num a => Dual a -> a #
Foldable Product	Since: base-4.8.0.0
Instance details Defined in Data.Foldable Methods fold :: Monoid m => Product m -> m # foldMap :: Monoid m => (a -> m) -> Product a -> m # foldMap' :: Monoid m => (a -> m) -> Product a -> m # foldr :: (a -> b -> b) -> b -> Product a -> b # foldr' :: (a -> b -> b) -> b -> Product a -> b # foldl :: (b -> a -> b) -> b -> Product a -> b # foldl' :: (b -> a -> b) -> b -> Product a -> b # foldr1 :: (a -> a -> a) -> Product a -> a # foldl1 :: (a -> a -> a) -> Product a -> a # toList :: Product a -> [a] # null :: Product a -> Bool # length :: Product a -> Int # elem :: Eq a => a -> Product a -> Bool # maximum :: Ord a => Product a -> a # minimum :: Ord a => Product a -> a # sum :: Num a => Product a -> a # product :: Num a => Product a -> a #
Foldable Sum	Since: base-4.8.0.0
Instance details Defined in Data.Foldable Methods fold :: Monoid m => Sum m -> m # foldMap :: Monoid m => (a -> m) -> Sum a -> m # foldMap' :: Monoid m => (a -> m) -> Sum a -> m # foldr :: (a -> b -> b) -> b -> Sum a -> b # foldr' :: (a -> b -> b) -> b -> Sum a -> b # foldl :: (b -> a -> b) -> b -> Sum a -> b # foldl' :: (b -> a -> b) -> b -> Sum a -> b # foldr1 :: (a -> a -> a) -> Sum a -> a # foldl1 :: (a -> a -> a) -> Sum a -> a # toList :: Sum a -> [a] # null :: Sum a -> Bool # length :: Sum a -> Int # elem :: Eq a => a -> Sum a -> Bool # maximum :: Ord a => Sum a -> a # minimum :: Ord a => Sum a -> a # sum :: Num a => Sum a -> a # product :: Num a => Sum a -> a #
Foldable NonEmpty	Since: base-4.9.0.0
Instance details Defined in Data.Foldable Methods fold :: Monoid m => NonEmpty m -> m # foldMap :: Monoid m => (a -> m) -> NonEmpty a -> m # foldMap' :: Monoid m => (a -> m) -> NonEmpty a -> m # foldr :: (a -> b -> b) -> b -> NonEmpty a -> b # foldr' :: (a -> b -> b) -> b -> NonEmpty a -> b # foldl :: (b -> a -> b) -> b -> NonEmpty a -> b # foldl' :: (b -> a -> b) -> b -> NonEmpty a -> b # foldr1 :: (a -> a -> a) -> NonEmpty a -> a # foldl1 :: (a -> a -> a) -> NonEmpty a -> a # toList :: NonEmpty a -> [a] # null :: NonEmpty a -> Bool # length :: NonEmpty a -> Int # elem :: Eq a => a -> NonEmpty a -> Bool # maximum :: Ord a => NonEmpty a -> a # minimum :: Ord a => NonEmpty a -> a # sum :: Num a => NonEmpty a -> a # product :: Num a => NonEmpty a -> a #
Foldable Par1	Since: base-4.9.0.0
Instance details Defined in Data.Foldable Methods fold :: Monoid m => Par1 m -> m # foldMap :: Monoid m => (a -> m) -> Par1 a -> m # foldMap' :: Monoid m => (a -> m) -> Par1 a -> m # foldr :: (a -> b -> b) -> b -> Par1 a -> b # foldr' :: (a -> b -> b) -> b -> Par1 a -> b # foldl :: (b -> a -> b) -> b -> Par1 a -> b # foldl' :: (b -> a -> b) -> b -> Par1 a -> b # foldr1 :: (a -> a -> a) -> Par1 a -> a # foldl1 :: (a -> a -> a) -> Par1 a -> a # toList :: Par1 a -> [a] # null :: Par1 a -> Bool # length :: Par1 a -> Int # elem :: Eq a => a -> Par1 a -> Bool # maximum :: Ord a => Par1 a -> a # minimum :: Ord a => Par1 a -> a # sum :: Num a => Par1 a -> a # product :: Num a => Par1 a -> a #
Foldable Maybe	Since: base-2.1
Instance details Defined in Data.Foldable Methods fold :: Monoid m => Maybe m -> m # foldMap :: Monoid m => (a -> m) -> Maybe a -> m # foldMap' :: Monoid m => (a -> m) -> Maybe a -> m # foldr :: (a -> b -> b) -> b -> Maybe a -> b # foldr' :: (a -> b -> b) -> b -> Maybe a -> b # foldl :: (b -> a -> b) -> b -> Maybe a -> b # foldl' :: (b -> a -> b) -> b -> Maybe a -> b # foldr1 :: (a -> a -> a) -> Maybe a -> a # foldl1 :: (a -> a -> a) -> Maybe a -> a # toList :: Maybe a -> [a] # null :: Maybe a -> Bool # length :: Maybe a -> Int # elem :: Eq a => a -> Maybe a -> Bool # maximum :: Ord a => Maybe a -> a # minimum :: Ord a => Maybe a -> a # sum :: Num a => Maybe a -> a # product :: Num a => Maybe a -> a #
Foldable Solo	Since: base-4.15
Instance details Defined in Data.Foldable Methods fold :: Monoid m => Solo m -> m # foldMap :: Monoid m => (a -> m) -> Solo a -> m # foldMap' :: Monoid m => (a -> m) -> Solo a -> m # foldr :: (a -> b -> b) -> b -> Solo a -> b # foldr' :: (a -> b -> b) -> b -> Solo a -> b # foldl :: (b -> a -> b) -> b -> Solo a -> b # foldl' :: (b -> a -> b) -> b -> Solo a -> b # foldr1 :: (a -> a -> a) -> Solo a -> a # foldl1 :: (a -> a -> a) -> Solo a -> a # toList :: Solo a -> [a] # null :: Solo a -> Bool # length :: Solo a -> Int # elem :: Eq a => a -> Solo a -> Bool # maximum :: Ord a => Solo a -> a # minimum :: Ord a => Solo a -> a # sum :: Num a => Solo a -> a # product :: Num a => Solo a -> a #
Foldable List	Since: base-2.1
Instance details Defined in Data.Foldable Methods fold :: Monoid m => [m] -> m # foldMap :: Monoid m => (a -> m) -> [a] -> m # foldMap' :: Monoid m => (a -> m) -> [a] -> m # foldr :: (a -> b -> b) -> b -> [a] -> b # foldr' :: (a -> b -> b) -> b -> [a] -> b # foldl :: (b -> a -> b) -> b -> [a] -> b # foldl' :: (b -> a -> b) -> b -> [a] -> b # foldr1 :: (a -> a -> a) -> [a] -> a # foldl1 :: (a -> a -> a) -> [a] -> a # toList :: [a] -> [a] # null :: [a] -> Bool # length :: [a] -> Int # elem :: Eq a => a -> [a] -> Bool # maximum :: Ord a => [a] -> a # minimum :: Ord a => [a] -> a # sum :: Num a => [a] -> a # product :: Num a => [a] -> a #
Foldable (Either a)	Since: base-4.7.0.0
Instance details Defined in Data.Foldable Methods fold :: Monoid m => Either a m -> m # foldMap :: Monoid m => (a0 -> m) -> Either a a0 -> m # foldMap' :: Monoid m => (a0 -> m) -> Either a a0 -> m # foldr :: (a0 -> b -> b) -> b -> Either a a0 -> b # foldr' :: (a0 -> b -> b) -> b -> Either a a0 -> b # foldl :: (b -> a0 -> b) -> b -> Either a a0 -> b # foldl' :: (b -> a0 -> b) -> b -> Either a a0 -> b # foldr1 :: (a0 -> a0 -> a0) -> Either a a0 -> a0 # foldl1 :: (a0 -> a0 -> a0) -> Either a a0 -> a0 # toList :: Either a a0 -> [a0] # null :: Either a a0 -> Bool # length :: Either a a0 -> Int # elem :: Eq a0 => a0 -> Either a a0 -> Bool # maximum :: Ord a0 => Either a a0 -> a0 # minimum :: Ord a0 => Either a a0 -> a0 # sum :: Num a0 => Either a a0 -> a0 # product :: Num a0 => Either a a0 -> a0 #
Foldable (Proxy :: Type -> Type)	Since: base-4.7.0.0
Instance details Defined in Data.Foldable Methods fold :: Monoid m => Proxy m -> m # foldMap :: Monoid m => (a -> m) -> Proxy a -> m # foldMap' :: Monoid m => (a -> m) -> Proxy a -> m # foldr :: (a -> b -> b) -> b -> Proxy a -> b # foldr' :: (a -> b -> b) -> b -> Proxy a -> b # foldl :: (b -> a -> b) -> b -> Proxy a -> b # foldl' :: (b -> a -> b) -> b -> Proxy a -> b # foldr1 :: (a -> a -> a) -> Proxy a -> a # foldl1 :: (a -> a -> a) -> Proxy a -> a # toList :: Proxy a -> [a] # null :: Proxy a -> Bool # length :: Proxy a -> Int # elem :: Eq a => a -> Proxy a -> Bool # maximum :: Ord a => Proxy a -> a # minimum :: Ord a => Proxy a -> a # sum :: Num a => Proxy a -> a # product :: Num a => Proxy a -> a #
Foldable (Arg a)	Since: base-4.9.0.0
Instance details Defined in Data.Semigroup Methods fold :: Monoid m => Arg a m -> m # foldMap :: Monoid m => (a0 -> m) -> Arg a a0 -> m # foldMap' :: Monoid m => (a0 -> m) -> Arg a a0 -> m # foldr :: (a0 -> b -> b) -> b -> Arg a a0 -> b # foldr' :: (a0 -> b -> b) -> b -> Arg a a0 -> b # foldl :: (b -> a0 -> b) -> b -> Arg a a0 -> b # foldl' :: (b -> a0 -> b) -> b -> Arg a a0 -> b # foldr1 :: (a0 -> a0 -> a0) -> Arg a a0 -> a0 # foldl1 :: (a0 -> a0 -> a0) -> Arg a a0 -> a0 # toList :: Arg a a0 -> [a0] # null :: Arg a a0 -> Bool # length :: Arg a a0 -> Int # elem :: Eq a0 => a0 -> Arg a a0 -> Bool # maximum :: Ord a0 => Arg a a0 -> a0 # minimum :: Ord a0 => Arg a a0 -> a0 # sum :: Num a0 => Arg a a0 -> a0 # product :: Num a0 => Arg a a0 -> a0 #
Foldable (Array i)	Since: base-4.8.0.0
Instance details Defined in Data.Foldable Methods fold :: Monoid m => Array i m -> m # foldMap :: Monoid m => (a -> m) -> Array i a -> m # foldMap' :: Monoid m => (a -> m) -> Array i a -> m # foldr :: (a -> b -> b) -> b -> Array i a -> b # foldr' :: (a -> b -> b) -> b -> Array i a -> b # foldl :: (b -> a -> b) -> b -> Array i a -> b # foldl' :: (b -> a -> b) -> b -> Array i a -> b # foldr1 :: (a -> a -> a) -> Array i a -> a # foldl1 :: (a -> a -> a) -> Array i a -> a # toList :: Array i a -> [a] # null :: Array i a -> Bool # length :: Array i a -> Int # elem :: Eq a => a -> Array i a -> Bool # maximum :: Ord a => Array i a -> a # minimum :: Ord a => Array i a -> a # sum :: Num a => Array i a -> a # product :: Num a => Array i a -> a #
Foldable (U1 :: Type -> Type)	Since: base-4.9.0.0
Instance details Defined in Data.Foldable Methods fold :: Monoid m => U1 m -> m # foldMap :: Monoid m => (a -> m) -> U1 a -> m # foldMap' :: Monoid m => (a -> m) -> U1 a -> m # foldr :: (a -> b -> b) -> b -> U1 a -> b # foldr' :: (a -> b -> b) -> b -> U1 a -> b # foldl :: (b -> a -> b) -> b -> U1 a -> b # foldl' :: (b -> a -> b) -> b -> U1 a -> b # foldr1 :: (a -> a -> a) -> U1 a -> a # foldl1 :: (a -> a -> a) -> U1 a -> a # toList :: U1 a -> [a] # null :: U1 a -> Bool # length :: U1 a -> Int # elem :: Eq a => a -> U1 a -> Bool # maximum :: Ord a => U1 a -> a # minimum :: Ord a => U1 a -> a # sum :: Num a => U1 a -> a # product :: Num a => U1 a -> a #
Foldable (UAddr :: Type -> Type)	Since: base-4.9.0.0
Instance details Defined in Data.Foldable Methods fold :: Monoid m => UAddr m -> m # foldMap :: Monoid m => (a -> m) -> UAddr a -> m # foldMap' :: Monoid m => (a -> m) -> UAddr a -> m # foldr :: (a -> b -> b) -> b -> UAddr a -> b # foldr' :: (a -> b -> b) -> b -> UAddr a -> b # foldl :: (b -> a -> b) -> b -> UAddr a -> b # foldl' :: (b -> a -> b) -> b -> UAddr a -> b # foldr1 :: (a -> a -> a) -> UAddr a -> a # foldl1 :: (a -> a -> a) -> UAddr a -> a # toList :: UAddr a -> [a] # null :: UAddr a -> Bool # length :: UAddr a -> Int # elem :: Eq a => a -> UAddr a -> Bool # maximum :: Ord a => UAddr a -> a # minimum :: Ord a => UAddr a -> a # sum :: Num a => UAddr a -> a # product :: Num a => UAddr a -> a #
Foldable (UChar :: Type -> Type)	Since: base-4.9.0.0
Instance details Defined in Data.Foldable Methods fold :: Monoid m => UChar m -> m # foldMap :: Monoid m => (a -> m) -> UChar a -> m # foldMap' :: Monoid m => (a -> m) -> UChar a -> m # foldr :: (a -> b -> b) -> b -> UChar a -> b # foldr' :: (a -> b -> b) -> b -> UChar a -> b # foldl :: (b -> a -> b) -> b -> UChar a -> b # foldl' :: (b -> a -> b) -> b -> UChar a -> b # foldr1 :: (a -> a -> a) -> UChar a -> a # foldl1 :: (a -> a -> a) -> UChar a -> a # toList :: UChar a -> [a] # null :: UChar a -> Bool # length :: UChar a -> Int # elem :: Eq a => a -> UChar a -> Bool # maximum :: Ord a => UChar a -> a # minimum :: Ord a => UChar a -> a # sum :: Num a => UChar a -> a # product :: Num a => UChar a -> a #
Foldable (UDouble :: Type -> Type)	Since: base-4.9.0.0
Instance details Defined in Data.Foldable Methods fold :: Monoid m => UDouble m -> m # foldMap :: Monoid m => (a -> m) -> UDouble a -> m # foldMap' :: Monoid m => (a -> m) -> UDouble a -> m # foldr :: (a -> b -> b) -> b -> UDouble a -> b # foldr' :: (a -> b -> b) -> b -> UDouble a -> b # foldl :: (b -> a -> b) -> b -> UDouble a -> b # foldl' :: (b -> a -> b) -> b -> UDouble a -> b # foldr1 :: (a -> a -> a) -> UDouble a -> a # foldl1 :: (a -> a -> a) -> UDouble a -> a # toList :: UDouble a -> [a] # null :: UDouble a -> Bool # length :: UDouble a -> Int # elem :: Eq a => a -> UDouble a -> Bool # maximum :: Ord a => UDouble a -> a # minimum :: Ord a => UDouble a -> a # sum :: Num a => UDouble a -> a # product :: Num a => UDouble a -> a #
Foldable (UFloat :: Type -> Type)	Since: base-4.9.0.0
Instance details Defined in Data.Foldable Methods fold :: Monoid m => UFloat m -> m # foldMap :: Monoid m => (a -> m) -> UFloat a -> m # foldMap' :: Monoid m => (a -> m) -> UFloat a -> m # foldr :: (a -> b -> b) -> b -> UFloat a -> b # foldr' :: (a -> b -> b) -> b -> UFloat a -> b # foldl :: (b -> a -> b) -> b -> UFloat a -> b # foldl' :: (b -> a -> b) -> b -> UFloat a -> b # foldr1 :: (a -> a -> a) -> UFloat a -> a # foldl1 :: (a -> a -> a) -> UFloat a -> a # toList :: UFloat a -> [a] # null :: UFloat a -> Bool # length :: UFloat a -> Int # elem :: Eq a => a -> UFloat a -> Bool # maximum :: Ord a => UFloat a -> a # minimum :: Ord a => UFloat a -> a # sum :: Num a => UFloat a -> a # product :: Num a => UFloat a -> a #
Foldable (UInt :: Type -> Type)	Since: base-4.9.0.0
Instance details Defined in Data.Foldable Methods fold :: Monoid m => UInt m -> m # foldMap :: Monoid m => (a -> m) -> UInt a -> m # foldMap' :: Monoid m => (a -> m) -> UInt a -> m # foldr :: (a -> b -> b) -> b -> UInt a -> b # foldr' :: (a -> b -> b) -> b -> UInt a -> b # foldl :: (b -> a -> b) -> b -> UInt a -> b # foldl' :: (b -> a -> b) -> b -> UInt a -> b # foldr1 :: (a -> a -> a) -> UInt a -> a # foldl1 :: (a -> a -> a) -> UInt a -> a # toList :: UInt a -> [a] # null :: UInt a -> Bool # length :: UInt a -> Int # elem :: Eq a => a -> UInt a -> Bool # maximum :: Ord a => UInt a -> a # minimum :: Ord a => UInt a -> a # sum :: Num a => UInt a -> a # product :: Num a => UInt a -> a #
Foldable (UWord :: Type -> Type)	Since: base-4.9.0.0
Instance details Defined in Data.Foldable Methods fold :: Monoid m => UWord m -> m # foldMap :: Monoid m => (a -> m) -> UWord a -> m # foldMap' :: Monoid m => (a -> m) -> UWord a -> m # foldr :: (a -> b -> b) -> b -> UWord a -> b # foldr' :: (a -> b -> b) -> b -> UWord a -> b # foldl :: (b -> a -> b) -> b -> UWord a -> b # foldl' :: (b -> a -> b) -> b -> UWord a -> b # foldr1 :: (a -> a -> a) -> UWord a -> a # foldl1 :: (a -> a -> a) -> UWord a -> a # toList :: UWord a -> [a] # null :: UWord a -> Bool # length :: UWord a -> Int # elem :: Eq a => a -> UWord a -> Bool # maximum :: Ord a => UWord a -> a # minimum :: Ord a => UWord a -> a # sum :: Num a => UWord a -> a # product :: Num a => UWord a -> a #
Foldable (V1 :: Type -> Type)	Since: base-4.9.0.0
Instance details Defined in Data.Foldable Methods fold :: Monoid m => V1 m -> m # foldMap :: Monoid m => (a -> m) -> V1 a -> m # foldMap' :: Monoid m => (a -> m) -> V1 a -> m # foldr :: (a -> b -> b) -> b -> V1 a -> b # foldr' :: (a -> b -> b) -> b -> V1 a -> b # foldl :: (b -> a -> b) -> b -> V1 a -> b # foldl' :: (b -> a -> b) -> b -> V1 a -> b # foldr1 :: (a -> a -> a) -> V1 a -> a # foldl1 :: (a -> a -> a) -> V1 a -> a # toList :: V1 a -> [a] # null :: V1 a -> Bool # length :: V1 a -> Int # elem :: Eq a => a -> V1 a -> Bool # maximum :: Ord a => V1 a -> a # minimum :: Ord a => V1 a -> a # sum :: Num a => V1 a -> a # product :: Num a => V1 a -> a #
Foldable m => Foldable (ListT m) Source #
Instance details Defined in Pipes Methods fold :: Monoid m0 => ListT m m0 -> m0 # foldMap :: Monoid m0 => (a -> m0) -> ListT m a -> m0 # foldMap' :: Monoid m0 => (a -> m0) -> ListT m a -> m0 # foldr :: (a -> b -> b) -> b -> ListT m a -> b # foldr' :: (a -> b -> b) -> b -> ListT m a -> b # foldl :: (b -> a -> b) -> b -> ListT m a -> b # foldl' :: (b -> a -> b) -> b -> ListT m a -> b # foldr1 :: (a -> a -> a) -> ListT m a -> a # foldl1 :: (a -> a -> a) -> ListT m a -> a # toList :: ListT m a -> [a] # null :: ListT m a -> Bool # length :: ListT m a -> Int # elem :: Eq a => a -> ListT m a -> Bool # maximum :: Ord a => ListT m a -> a # minimum :: Ord a => ListT m a -> a # sum :: Num a => ListT m a -> a # product :: Num a => ListT m a -> a #
Foldable f => Foldable (Lift f)
Instance details Defined in Control.Applicative.Lift Methods fold :: Monoid m => Lift f m -> m # foldMap :: Monoid m => (a -> m) -> Lift f a -> m # foldMap' :: Monoid m => (a -> m) -> Lift f a -> m # foldr :: (a -> b -> b) -> b -> Lift f a -> b # foldr' :: (a -> b -> b) -> b -> Lift f a -> b # foldl :: (b -> a -> b) -> b -> Lift f a -> b # foldl' :: (b -> a -> b) -> b -> Lift f a -> b # foldr1 :: (a -> a -> a) -> Lift f a -> a # foldl1 :: (a -> a -> a) -> Lift f a -> a # toList :: Lift f a -> [a] # null :: Lift f a -> Bool # length :: Lift f a -> Int # elem :: Eq a => a -> Lift f a -> Bool # maximum :: Ord a => Lift f a -> a # minimum :: Ord a => Lift f a -> a # sum :: Num a => Lift f a -> a # product :: Num a => Lift f a -> a #
Foldable f => Foldable (MaybeT f)
Instance details Defined in Control.Monad.Trans.Maybe Methods fold :: Monoid m => MaybeT f m -> m # foldMap :: Monoid m => (a -> m) -> MaybeT f a -> m # foldMap' :: Monoid m => (a -> m) -> MaybeT f a -> m # foldr :: (a -> b -> b) -> b -> MaybeT f a -> b # foldr' :: (a -> b -> b) -> b -> MaybeT f a -> b # foldl :: (b -> a -> b) -> b -> MaybeT f a -> b # foldl' :: (b -> a -> b) -> b -> MaybeT f a -> b # foldr1 :: (a -> a -> a) -> MaybeT f a -> a # foldl1 :: (a -> a -> a) -> MaybeT f a -> a # toList :: MaybeT f a -> [a] # null :: MaybeT f a -> Bool # length :: MaybeT f a -> Int # elem :: Eq a => a -> MaybeT f a -> Bool # maximum :: Ord a => MaybeT f a -> a # minimum :: Ord a => MaybeT f a -> a # sum :: Num a => MaybeT f a -> a # product :: Num a => MaybeT f a -> a #
Foldable ((,) a)	Since: base-4.7.0.0
Instance details Defined in Data.Foldable Methods fold :: Monoid m => (a, m) -> m # foldMap :: Monoid m => (a0 -> m) -> (a, a0) -> m # foldMap' :: Monoid m => (a0 -> m) -> (a, a0) -> m # foldr :: (a0 -> b -> b) -> b -> (a, a0) -> b # foldr' :: (a0 -> b -> b) -> b -> (a, a0) -> b # foldl :: (b -> a0 -> b) -> b -> (a, a0) -> b # foldl' :: (b -> a0 -> b) -> b -> (a, a0) -> b # foldr1 :: (a0 -> a0 -> a0) -> (a, a0) -> a0 # foldl1 :: (a0 -> a0 -> a0) -> (a, a0) -> a0 # toList :: (a, a0) -> [a0] # null :: (a, a0) -> Bool # length :: (a, a0) -> Int # elem :: Eq a0 => a0 -> (a, a0) -> Bool # maximum :: Ord a0 => (a, a0) -> a0 # minimum :: Ord a0 => (a, a0) -> a0 # sum :: Num a0 => (a, a0) -> a0 # product :: Num a0 => (a, a0) -> a0 #
Foldable f => Foldable (Ap f)	Since: base-4.12.0.0
Instance details Defined in Data.Foldable Methods fold :: Monoid m => Ap f m -> m # foldMap :: Monoid m => (a -> m) -> Ap f a -> m # foldMap' :: Monoid m => (a -> m) -> Ap f a -> m # foldr :: (a -> b -> b) -> b -> Ap f a -> b # foldr' :: (a -> b -> b) -> b -> Ap f a -> b # foldl :: (b -> a -> b) -> b -> Ap f a -> b # foldl' :: (b -> a -> b) -> b -> Ap f a -> b # foldr1 :: (a -> a -> a) -> Ap f a -> a # foldl1 :: (a -> a -> a) -> Ap f a -> a # toList :: Ap f a -> [a] # null :: Ap f a -> Bool # length :: Ap f a -> Int # elem :: Eq a => a -> Ap f a -> Bool # maximum :: Ord a => Ap f a -> a # minimum :: Ord a => Ap f a -> a # sum :: Num a => Ap f a -> a # product :: Num a => Ap f a -> a #
Foldable f => Foldable (Alt f)	Since: base-4.12.0.0
Instance details Defined in Data.Foldable Methods fold :: Monoid m => Alt f m -> m # foldMap :: Monoid m => (a -> m) -> Alt f a -> m # foldMap' :: Monoid m => (a -> m) -> Alt f a -> m # foldr :: (a -> b -> b) -> b -> Alt f a -> b # foldr' :: (a -> b -> b) -> b -> Alt f a -> b # foldl :: (b -> a -> b) -> b -> Alt f a -> b # foldl' :: (b -> a -> b) -> b -> Alt f a -> b # foldr1 :: (a -> a -> a) -> Alt f a -> a # foldl1 :: (a -> a -> a) -> Alt f a -> a # toList :: Alt f a -> [a] # null :: Alt f a -> Bool # length :: Alt f a -> Int # elem :: Eq a => a -> Alt f a -> Bool # maximum :: Ord a => Alt f a -> a # minimum :: Ord a => Alt f a -> a # sum :: Num a => Alt f a -> a # product :: Num a => Alt f a -> a #
Foldable f => Foldable (Rec1 f)	Since: base-4.9.0.0
Instance details Defined in Data.Foldable Methods fold :: Monoid m => Rec1 f m -> m # foldMap :: Monoid m => (a -> m) -> Rec1 f a -> m # foldMap' :: Monoid m => (a -> m) -> Rec1 f a -> m # foldr :: (a -> b -> b) -> b -> Rec1 f a -> b # foldr' :: (a -> b -> b) -> b -> Rec1 f a -> b # foldl :: (b -> a -> b) -> b -> Rec1 f a -> b # foldl' :: (b -> a -> b) -> b -> Rec1 f a -> b # foldr1 :: (a -> a -> a) -> Rec1 f a -> a # foldl1 :: (a -> a -> a) -> Rec1 f a -> a # toList :: Rec1 f a -> [a] # null :: Rec1 f a -> Bool # length :: Rec1 f a -> Int # elem :: Eq a => a -> Rec1 f a -> Bool # maximum :: Ord a => Rec1 f a -> a # minimum :: Ord a => Rec1 f a -> a # sum :: Num a => Rec1 f a -> a # product :: Num a => Rec1 f a -> a #
Foldable f => Foldable (Backwards f)	Derived instance.
Instance details Defined in Control.Applicative.Backwards Methods fold :: Monoid m => Backwards f m -> m # foldMap :: Monoid m => (a -> m) -> Backwards f a -> m # foldMap' :: Monoid m => (a -> m) -> Backwards f a -> m # foldr :: (a -> b -> b) -> b -> Backwards f a -> b # foldr' :: (a -> b -> b) -> b -> Backwards f a -> b # foldl :: (b -> a -> b) -> b -> Backwards f a -> b # foldl' :: (b -> a -> b) -> b -> Backwards f a -> b # foldr1 :: (a -> a -> a) -> Backwards f a -> a # foldl1 :: (a -> a -> a) -> Backwards f a -> a # toList :: Backwards f a -> [a] # null :: Backwards f a -> Bool # length :: Backwards f a -> Int # elem :: Eq a => a -> Backwards f a -> Bool # maximum :: Ord a => Backwards f a -> a # minimum :: Ord a => Backwards f a -> a # sum :: Num a => Backwards f a -> a # product :: Num a => Backwards f a -> a #
Foldable f => Foldable (ExceptT e f)
Instance details Defined in Control.Monad.Trans.Except Methods fold :: Monoid m => ExceptT e f m -> m # foldMap :: Monoid m => (a -> m) -> ExceptT e f a -> m # foldMap' :: Monoid m => (a -> m) -> ExceptT e f a -> m # foldr :: (a -> b -> b) -> b -> ExceptT e f a -> b # foldr' :: (a -> b -> b) -> b -> ExceptT e f a -> b # foldl :: (b -> a -> b) -> b -> ExceptT e f a -> b # foldl' :: (b -> a -> b) -> b -> ExceptT e f a -> b # foldr1 :: (a -> a -> a) -> ExceptT e f a -> a # foldl1 :: (a -> a -> a) -> ExceptT e f a -> a # toList :: ExceptT e f a -> [a] # null :: ExceptT e f a -> Bool # length :: ExceptT e f a -> Int # elem :: Eq a => a -> ExceptT e f a -> Bool # maximum :: Ord a => ExceptT e f a -> a # minimum :: Ord a => ExceptT e f a -> a # sum :: Num a => ExceptT e f a -> a # product :: Num a => ExceptT e f a -> a #
Foldable f => Foldable (IdentityT f)
Instance details Defined in Control.Monad.Trans.Identity Methods fold :: Monoid m => IdentityT f m -> m # foldMap :: Monoid m => (a -> m) -> IdentityT f a -> m # foldMap' :: Monoid m => (a -> m) -> IdentityT f a -> m # foldr :: (a -> b -> b) -> b -> IdentityT f a -> b # foldr' :: (a -> b -> b) -> b -> IdentityT f a -> b # foldl :: (b -> a -> b) -> b -> IdentityT f a -> b # foldl' :: (b -> a -> b) -> b -> IdentityT f a -> b # foldr1 :: (a -> a -> a) -> IdentityT f a -> a # foldl1 :: (a -> a -> a) -> IdentityT f a -> a # toList :: IdentityT f a -> [a] # null :: IdentityT f a -> Bool # length :: IdentityT f a -> Int # elem :: Eq a => a -> IdentityT f a -> Bool # maximum :: Ord a => IdentityT f a -> a # minimum :: Ord a => IdentityT f a -> a # sum :: Num a => IdentityT f a -> a # product :: Num a => IdentityT f a -> a #
Foldable f => Foldable (WriterT w f)
Instance details Defined in Control.Monad.Trans.Writer.Lazy Methods fold :: Monoid m => WriterT w f m -> m # foldMap :: Monoid m => (a -> m) -> WriterT w f a -> m # foldMap' :: Monoid m => (a -> m) -> WriterT w f a -> m # foldr :: (a -> b -> b) -> b -> WriterT w f a -> b # foldr' :: (a -> b -> b) -> b -> WriterT w f a -> b # foldl :: (b -> a -> b) -> b -> WriterT w f a -> b # foldl' :: (b -> a -> b) -> b -> WriterT w f a -> b # foldr1 :: (a -> a -> a) -> WriterT w f a -> a # foldl1 :: (a -> a -> a) -> WriterT w f a -> a # toList :: WriterT w f a -> [a] # null :: WriterT w f a -> Bool # length :: WriterT w f a -> Int # elem :: Eq a => a -> WriterT w f a -> Bool # maximum :: Ord a => WriterT w f a -> a # minimum :: Ord a => WriterT w f a -> a # sum :: Num a => WriterT w f a -> a # product :: Num a => WriterT w f a -> a #
Foldable f => Foldable (WriterT w f)
Instance details Defined in Control.Monad.Trans.Writer.Strict Methods fold :: Monoid m => WriterT w f m -> m # foldMap :: Monoid m => (a -> m) -> WriterT w f a -> m # foldMap' :: Monoid m => (a -> m) -> WriterT w f a -> m # foldr :: (a -> b -> b) -> b -> WriterT w f a -> b # foldr' :: (a -> b -> b) -> b -> WriterT w f a -> b # foldl :: (b -> a -> b) -> b -> WriterT w f a -> b # foldl' :: (b -> a -> b) -> b -> WriterT w f a -> b # foldr1 :: (a -> a -> a) -> WriterT w f a -> a # foldl1 :: (a -> a -> a) -> WriterT w f a -> a # toList :: WriterT w f a -> [a] # null :: WriterT w f a -> Bool # length :: WriterT w f a -> Int # elem :: Eq a => a -> WriterT w f a -> Bool # maximum :: Ord a => WriterT w f a -> a # minimum :: Ord a => WriterT w f a -> a # sum :: Num a => WriterT w f a -> a # product :: Num a => WriterT w f a -> a #
Foldable (Constant a :: Type -> Type)
Instance details Defined in Data.Functor.Constant Methods fold :: Monoid m => Constant a m -> m # foldMap :: Monoid m => (a0 -> m) -> Constant a a0 -> m # foldMap' :: Monoid m => (a0 -> m) -> Constant a a0 -> m # foldr :: (a0 -> b -> b) -> b -> Constant a a0 -> b # foldr' :: (a0 -> b -> b) -> b -> Constant a a0 -> b # foldl :: (b -> a0 -> b) -> b -> Constant a a0 -> b # foldl' :: (b -> a0 -> b) -> b -> Constant a a0 -> b # foldr1 :: (a0 -> a0 -> a0) -> Constant a a0 -> a0 # foldl1 :: (a0 -> a0 -> a0) -> Constant a a0 -> a0 # toList :: Constant a a0 -> [a0] # null :: Constant a a0 -> Bool # length :: Constant a a0 -> Int # elem :: Eq a0 => a0 -> Constant a a0 -> Bool # maximum :: Ord a0 => Constant a a0 -> a0 # minimum :: Ord a0 => Constant a a0 -> a0 # sum :: Num a0 => Constant a a0 -> a0 # product :: Num a0 => Constant a a0 -> a0 #
(Foldable f, Foldable g) => Foldable (f :*: g)	Since: base-4.9.0.0
Instance details Defined in Data.Foldable Methods fold :: Monoid m => (f :: g) m -> m # foldMap :: Monoid m => (a -> m) -> (f :: g) a -> m # foldMap' :: Monoid m => (a -> m) -> (f :: g) a -> m # foldr :: (a -> b -> b) -> b -> (f :: g) a -> b # foldr' :: (a -> b -> b) -> b -> (f :: g) a -> b # foldl :: (b -> a -> b) -> b -> (f :: g) a -> b # foldl' :: (b -> a -> b) -> b -> (f :: g) a -> b # foldr1 :: (a -> a -> a) -> (f :: g) a -> a # foldl1 :: (a -> a -> a) -> (f :: g) a -> a # toList :: (f :: g) a -> [a] # null :: (f :: g) a -> Bool # length :: (f :: g) a -> Int # elem :: Eq a => a -> (f :: g) a -> Bool # maximum :: Ord a => (f :: g) a -> a # minimum :: Ord a => (f :: g) a -> a # sum :: Num a => (f :: g) a -> a # product :: Num a => (f :*: g) a -> a #
(Foldable f, Foldable g) => Foldable (f :+: g)	Since: base-4.9.0.0
Instance details Defined in Data.Foldable Methods fold :: Monoid m => (f :+: g) m -> m # foldMap :: Monoid m => (a -> m) -> (f :+: g) a -> m # foldMap' :: Monoid m => (a -> m) -> (f :+: g) a -> m # foldr :: (a -> b -> b) -> b -> (f :+: g) a -> b # foldr' :: (a -> b -> b) -> b -> (f :+: g) a -> b # foldl :: (b -> a -> b) -> b -> (f :+: g) a -> b # foldl' :: (b -> a -> b) -> b -> (f :+: g) a -> b # foldr1 :: (a -> a -> a) -> (f :+: g) a -> a # foldl1 :: (a -> a -> a) -> (f :+: g) a -> a # toList :: (f :+: g) a -> [a] # null :: (f :+: g) a -> Bool # length :: (f :+: g) a -> Int # elem :: Eq a => a -> (f :+: g) a -> Bool # maximum :: Ord a => (f :+: g) a -> a # minimum :: Ord a => (f :+: g) a -> a # sum :: Num a => (f :+: g) a -> a # product :: Num a => (f :+: g) a -> a #
Foldable (K1 i c :: Type -> Type)	Since: base-4.9.0.0
Instance details Defined in Data.Foldable Methods fold :: Monoid m => K1 i c m -> m # foldMap :: Monoid m => (a -> m) -> K1 i c a -> m # foldMap' :: Monoid m => (a -> m) -> K1 i c a -> m # foldr :: (a -> b -> b) -> b -> K1 i c a -> b # foldr' :: (a -> b -> b) -> b -> K1 i c a -> b # foldl :: (b -> a -> b) -> b -> K1 i c a -> b # foldl' :: (b -> a -> b) -> b -> K1 i c a -> b # foldr1 :: (a -> a -> a) -> K1 i c a -> a # foldl1 :: (a -> a -> a) -> K1 i c a -> a # toList :: K1 i c a -> [a] # null :: K1 i c a -> Bool # length :: K1 i c a -> Int # elem :: Eq a => a -> K1 i c a -> Bool # maximum :: Ord a => K1 i c a -> a # minimum :: Ord a => K1 i c a -> a # sum :: Num a => K1 i c a -> a # product :: Num a => K1 i c a -> a #
(Foldable f, Foldable g) => Foldable (f :.: g)	Since: base-4.9.0.0
Instance details Defined in Data.Foldable Methods fold :: Monoid m => (f :.: g) m -> m # foldMap :: Monoid m => (a -> m) -> (f :.: g) a -> m # foldMap' :: Monoid m => (a -> m) -> (f :.: g) a -> m # foldr :: (a -> b -> b) -> b -> (f :.: g) a -> b # foldr' :: (a -> b -> b) -> b -> (f :.: g) a -> b # foldl :: (b -> a -> b) -> b -> (f :.: g) a -> b # foldl' :: (b -> a -> b) -> b -> (f :.: g) a -> b # foldr1 :: (a -> a -> a) -> (f :.: g) a -> a # foldl1 :: (a -> a -> a) -> (f :.: g) a -> a # toList :: (f :.: g) a -> [a] # null :: (f :.: g) a -> Bool # length :: (f :.: g) a -> Int # elem :: Eq a => a -> (f :.: g) a -> Bool # maximum :: Ord a => (f :.: g) a -> a # minimum :: Ord a => (f :.: g) a -> a # sum :: Num a => (f :.: g) a -> a # product :: Num a => (f :.: g) a -> a #
Foldable f => Foldable (M1 i c f)	Since: base-4.9.0.0
Instance details Defined in Data.Foldable Methods fold :: Monoid m => M1 i c f m -> m # foldMap :: Monoid m => (a -> m) -> M1 i c f a -> m # foldMap' :: Monoid m => (a -> m) -> M1 i c f a -> m # foldr :: (a -> b -> b) -> b -> M1 i c f a -> b # foldr' :: (a -> b -> b) -> b -> M1 i c f a -> b # foldl :: (b -> a -> b) -> b -> M1 i c f a -> b # foldl' :: (b -> a -> b) -> b -> M1 i c f a -> b # foldr1 :: (a -> a -> a) -> M1 i c f a -> a # foldl1 :: (a -> a -> a) -> M1 i c f a -> a # toList :: M1 i c f a -> [a] # null :: M1 i c f a -> Bool # length :: M1 i c f a -> Int # elem :: Eq a => a -> M1 i c f a -> Bool # maximum :: Ord a => M1 i c f a -> a # minimum :: Ord a => M1 i c f a -> a # sum :: Num a => M1 i c f a -> a # product :: Num a => M1 i c f a -> a #