Copyright | (c) Andy Gill 2001 (c) Oregon Graduate Institute of Science and Technology 2001 |
---|---|
License | BSD-style (see the file libraries/base/LICENSE) |
Maintainer | libraries@haskell.org |
Stability | experimental |
Portability | portable |
Safe Haskell | Trustworthy |
Language | Haskell2010 |
A class for monoids (types with an associative binary operation that has an identity) with various general-purpose instances.
Synopsis
- class Semigroup a => Monoid a where
- (<>) :: Semigroup a => a -> a -> a
- newtype Dual a = Dual {
- getDual :: a
- newtype Endo a = Endo {
- appEndo :: a -> a
- newtype All = All {}
- newtype Any = Any {}
- newtype Sum a = Sum {
- getSum :: a
- newtype Product a = Product {
- getProduct :: a
- newtype First a = First {}
- newtype Last a = Last {}
- newtype Alt f a = Alt {
- getAlt :: f a
Monoid
typeclass
class Semigroup a => Monoid a where Source #
The class of monoids (types with an associative binary operation that has an identity). Instances should satisfy the following laws:
x
<>
mempty
= xmempty
<>
x = xx
(<>
(y<>
z) = (x<>
y)<>
zSemigroup
law)mconcat
=foldr
'(<>)'mempty
The method names refer to the monoid of lists under concatenation, but there are many other instances.
Some types can be viewed as a monoid in more than one way,
e.g. both addition and multiplication on numbers.
In such cases we often define newtype
s and make those instances
of Monoid
, e.g. Sum
and Product
.
NOTE: Semigroup
is a superclass of Monoid
since base-4.11.0.0.
Identity of mappend
mappend :: a -> a -> a Source #
An associative operation
NOTE: This method is redundant and has the default
implementation
since base-4.11.0.0.mappend
= '(<>)'
Fold a list using the monoid.
For most types, the default definition for mconcat
will be
used, but the function is included in the class definition so
that an optimized version can be provided for specific types.
Instances
Monoid Ordering # | Since: 2.1 |
Monoid () # | Since: 2.1 |
Monoid Any # | Since: 2.1 |
Monoid All # | Since: 2.1 |
Monoid Lifetime # |
Since: 4.8.0.0 |
Monoid Event # | Since: 4.3.1.0 |
Monoid [a] # | Since: 2.1 |
Semigroup a => Monoid (Maybe a) # | Lift a semigroup into Since 4.11.0: constraint on inner Since: 2.1 |
Monoid a => Monoid (IO a) # | Since: 4.9.0.0 |
Monoid a => Monoid (Down a) # | Since: 4.11.0.0 |
Num a => Monoid (Product a) # | Since: 2.1 |
Num a => Monoid (Sum a) # | Since: 2.1 |
Monoid (Endo a) # | Since: 2.1 |
Monoid a => Monoid (Dual a) # | Since: 2.1 |
Monoid (Last a) # | Since: 2.1 |
Monoid (First a) # | Since: 2.1 |
Monoid a => Monoid (Identity a) # | |
Semigroup a => Monoid (Option a) # | Since: 4.9.0.0 |
Monoid m => Monoid (WrappedMonoid m) # | Since: 4.9.0.0 |
mempty :: WrappedMonoid m Source # mappend :: WrappedMonoid m -> WrappedMonoid m -> WrappedMonoid m Source # mconcat :: [WrappedMonoid m] -> WrappedMonoid m Source # | |
(Ord a, Bounded a) => Monoid (Max a) # | Since: 4.9.0.0 |
(Ord a, Bounded a) => Monoid (Min a) # | Since: 4.9.0.0 |
Monoid b => Monoid (a -> b) # | Since: 2.1 |
(Monoid a, Monoid b) => Monoid (a, b) # | Since: 2.1 |
Monoid a => Monoid (ST s a) # | Since: 4.11.0.0 |
Monoid (Proxy s) # | Since: 4.7.0.0 |
(Monoid a, Monoid b, Monoid c) => Monoid (a, b, c) # | Since: 2.1 |
Alternative f => Monoid (Alt f a) # | Since: 4.8.0.0 |
Monoid a => Monoid (Const a b) # | |
(Monoid a, Monoid b, Monoid c, Monoid d) => Monoid (a, b, c, d) # | Since: 2.1 |
(Monoid a, Monoid b, Monoid c, Monoid d, Monoid e) => Monoid (a, b, c, d, e) # | Since: 2.1 |
The dual of a Monoid
, obtained by swapping the arguments of mappend
.
>>>
getDual (mappend (Dual "Hello") (Dual "World"))
"WorldHello"
Instances
Monad Dual # | Since: 4.8.0.0 |
Functor Dual # | Since: 4.8.0.0 |
MonadFix Dual # | Since: 4.8.0.0 |
Applicative Dual # | Since: 4.8.0.0 |
Foldable Dual # | Since: 4.8.0.0 |
fold :: Monoid m => Dual m -> m Source # foldMap :: Monoid m => (a -> m) -> Dual a -> m Source # foldr :: (a -> b -> b) -> b -> Dual a -> b Source # foldr' :: (a -> b -> b) -> b -> Dual a -> b Source # foldl :: (b -> a -> b) -> b -> Dual a -> b Source # foldl' :: (b -> a -> b) -> b -> Dual a -> b Source # foldr1 :: (a -> a -> a) -> Dual a -> a Source # foldl1 :: (a -> a -> a) -> Dual a -> a Source # toList :: Dual a -> [a] Source # null :: Dual a -> Bool Source # length :: Dual a -> Int Source # elem :: Eq a => a -> Dual a -> Bool Source # maximum :: Ord a => Dual a -> a Source # minimum :: Ord a => Dual a -> a Source # | |
Traversable Dual # | Since: 4.8.0.0 |
MonadZip Dual # | Since: 4.8.0.0 |
Bounded a => Bounded (Dual a) # | |
Eq a => Eq (Dual a) # | |
Data a => Data (Dual a) # | Since: 4.8.0.0 |
gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Dual a -> c (Dual a) Source # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (Dual a) Source # toConstr :: Dual a -> Constr Source # dataTypeOf :: Dual a -> DataType Source # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (Dual a)) Source # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Dual a)) Source # gmapT :: (forall b. Data b => b -> b) -> Dual a -> Dual a Source # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Dual a -> r Source # gmapQr :: (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Dual a -> r Source # gmapQ :: (forall d. Data d => d -> u) -> Dual a -> [u] Source # gmapQi :: Int -> (forall d. Data d => d -> u) -> Dual a -> u Source # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Dual a -> m (Dual a) Source # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Dual a -> m (Dual a) Source # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Dual a -> m (Dual a) Source # | |
Ord a => Ord (Dual a) # | |
Read a => Read (Dual a) # | |
Show a => Show (Dual a) # | |
Generic (Dual a) # | |
Semigroup a => Semigroup (Dual a) # | Since: 4.9.0.0 |
Monoid a => Monoid (Dual a) # | Since: 2.1 |
Generic1 Dual # | |
type Rep (Dual a) # | |
type Rep1 Dual # | |
The monoid of endomorphisms under composition.
>>>
let computation = Endo ("Hello, " ++) <> Endo (++ "!")
>>>
appEndo computation "Haskell"
"Hello, Haskell!"
Bool
wrappers
Boolean monoid under conjunction (&&
).
>>>
getAll (All True <> mempty <> All False)
False
>>>
getAll (mconcat (map (\x -> All (even x)) [2,4,6,7,8]))
False
Instances
Bounded All # | |
Eq All # | |
Data All # | Since: 4.8.0.0 |
gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> All -> c All Source # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c All Source # toConstr :: All -> Constr Source # dataTypeOf :: All -> DataType Source # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c All) Source # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c All) Source # gmapT :: (forall b. Data b => b -> b) -> All -> All Source # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> All -> r Source # gmapQr :: (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> All -> r Source # gmapQ :: (forall d. Data d => d -> u) -> All -> [u] Source # gmapQi :: Int -> (forall d. Data d => d -> u) -> All -> u Source # gmapM :: Monad m => (forall d. Data d => d -> m d) -> All -> m All Source # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> All -> m All Source # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> All -> m All Source # | |
Ord All # | |
Read All # | |
Show All # | |
Generic All # | |
Semigroup All # | Since: 4.9.0.0 |
Monoid All # | Since: 2.1 |
type Rep All # | |
Boolean monoid under disjunction (||
).
>>>
getAny (Any True <> mempty <> Any False)
True
>>>
getAny (mconcat (map (\x -> Any (even x)) [2,4,6,7,8]))
True
Instances
Bounded Any # | |
Eq Any # | |
Data Any # | Since: 4.8.0.0 |
gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Any -> c Any Source # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c Any Source # toConstr :: Any -> Constr Source # dataTypeOf :: Any -> DataType Source # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c Any) Source # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c Any) Source # gmapT :: (forall b. Data b => b -> b) -> Any -> Any Source # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Any -> r Source # gmapQr :: (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Any -> r Source # gmapQ :: (forall d. Data d => d -> u) -> Any -> [u] Source # gmapQi :: Int -> (forall d. Data d => d -> u) -> Any -> u Source # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Any -> m Any Source # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Any -> m Any Source # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Any -> m Any Source # | |
Ord Any # | |
Read Any # | |
Show Any # | |
Generic Any # | |
Semigroup Any # | Since: 4.9.0.0 |
Monoid Any # | Since: 2.1 |
type Rep Any # | |
Num
wrappers
Monoid under addition.
>>>
getSum (Sum 1 <> Sum 2 <> mempty)
3
Instances
Monad Sum # | Since: 4.8.0.0 |
Functor Sum # | Since: 4.8.0.0 |
MonadFix Sum # | Since: 4.8.0.0 |
Applicative Sum # | Since: 4.8.0.0 |
Foldable Sum # | Since: 4.8.0.0 |
fold :: Monoid m => Sum m -> m Source # foldMap :: Monoid m => (a -> m) -> Sum a -> m Source # foldr :: (a -> b -> b) -> b -> Sum a -> b Source # foldr' :: (a -> b -> b) -> b -> Sum a -> b Source # foldl :: (b -> a -> b) -> b -> Sum a -> b Source # foldl' :: (b -> a -> b) -> b -> Sum a -> b Source # foldr1 :: (a -> a -> a) -> Sum a -> a Source # foldl1 :: (a -> a -> a) -> Sum a -> a Source # toList :: Sum a -> [a] Source # null :: Sum a -> Bool Source # length :: Sum a -> Int Source # elem :: Eq a => a -> Sum a -> Bool Source # maximum :: Ord a => Sum a -> a Source # minimum :: Ord a => Sum a -> a Source # | |
Traversable Sum # | Since: 4.8.0.0 |
MonadZip Sum # | Since: 4.8.0.0 |
Bounded a => Bounded (Sum a) # | |
Eq a => Eq (Sum a) # | |
Data a => Data (Sum a) # | Since: 4.8.0.0 |
gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Sum a -> c (Sum a) Source # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (Sum a) Source # toConstr :: Sum a -> Constr Source # dataTypeOf :: Sum a -> DataType Source # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (Sum a)) Source # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Sum a)) Source # gmapT :: (forall b. Data b => b -> b) -> Sum a -> Sum a Source # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Sum a -> r Source # gmapQr :: (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Sum a -> r Source # gmapQ :: (forall d. Data d => d -> u) -> Sum a -> [u] Source # gmapQi :: Int -> (forall d. Data d => d -> u) -> Sum a -> u Source # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Sum a -> m (Sum a) Source # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Sum a -> m (Sum a) Source # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Sum a -> m (Sum a) Source # | |
Num a => Num (Sum a) # | |
Ord a => Ord (Sum a) # | |
Read a => Read (Sum a) # | |
Show a => Show (Sum a) # | |
Generic (Sum a) # | |
Num a => Semigroup (Sum a) # | Since: 4.9.0.0 |
Num a => Monoid (Sum a) # | Since: 2.1 |
Generic1 Sum # | |
type Rep (Sum a) # | |
type Rep1 Sum # | |
Monoid under multiplication.
>>>
getProduct (Product 3 <> Product 4 <> mempty)
12
Product | |
|
Instances
Monad Product # | Since: 4.8.0.0 |
Functor Product # | Since: 4.8.0.0 |
MonadFix Product # | Since: 4.8.0.0 |
Applicative Product # | Since: 4.8.0.0 |
Foldable Product # | Since: 4.8.0.0 |
fold :: Monoid m => Product m -> m Source # foldMap :: Monoid m => (a -> m) -> Product a -> m Source # foldr :: (a -> b -> b) -> b -> Product a -> b Source # foldr' :: (a -> b -> b) -> b -> Product a -> b Source # foldl :: (b -> a -> b) -> b -> Product a -> b Source # foldl' :: (b -> a -> b) -> b -> Product a -> b Source # foldr1 :: (a -> a -> a) -> Product a -> a Source # foldl1 :: (a -> a -> a) -> Product a -> a Source # toList :: Product a -> [a] Source # null :: Product a -> Bool Source # length :: Product a -> Int Source # elem :: Eq a => a -> Product a -> Bool Source # maximum :: Ord a => Product a -> a Source # minimum :: Ord a => Product a -> a Source # | |
Traversable Product # | Since: 4.8.0.0 |
MonadZip Product # | Since: 4.8.0.0 |
Bounded a => Bounded (Product a) # | |
Eq a => Eq (Product a) # | |
Data a => Data (Product a) # | Since: 4.8.0.0 |
gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Product a -> c (Product a) Source # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (Product a) Source # toConstr :: Product a -> Constr Source # dataTypeOf :: Product a -> DataType Source # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (Product a)) Source # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Product a)) Source # gmapT :: (forall b. Data b => b -> b) -> Product a -> Product a Source # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Product a -> r Source # gmapQr :: (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Product a -> r Source # gmapQ :: (forall d. Data d => d -> u) -> Product a -> [u] Source # gmapQi :: Int -> (forall d. Data d => d -> u) -> Product a -> u Source # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Product a -> m (Product a) Source # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Product a -> m (Product a) Source # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Product a -> m (Product a) Source # | |
Num a => Num (Product a) # | |
(+) :: Product a -> Product a -> Product a Source # (-) :: Product a -> Product a -> Product a Source # (*) :: Product a -> Product a -> Product a Source # negate :: Product a -> Product a Source # abs :: Product a -> Product a Source # signum :: Product a -> Product a Source # fromInteger :: Integer -> Product a Source # | |
Ord a => Ord (Product a) # | |
Read a => Read (Product a) # | |
Show a => Show (Product a) # | |
Generic (Product a) # | |
Num a => Semigroup (Product a) # | Since: 4.9.0.0 |
Num a => Monoid (Product a) # | Since: 2.1 |
Generic1 Product # | |
type Rep (Product a) # | |
type Rep1 Product # | |
Maybe
wrappers
To implement find
or findLast
on any Foldable
:
findLast :: Foldable t => (a -> Bool) -> t a -> Maybe a findLast pred = getLast . foldMap (x -> if pred x then Last (Just x) else Last Nothing)
Much of Data.Map's interface can be implemented with
Data.Map.alter. Some of the rest can be implemented with a new
alterA
function and either First
or Last
:
alterA :: (Applicative f, Ord k) => (Maybe a -> f (Maybe a)) -> k -> Map k a -> f (Map k a) instance Monoid a => Applicative ((,) a) -- from Control.Applicative
insertLookupWithKey :: Ord k => (k -> v -> v -> v) -> k -> v -> Map k v -> (Maybe v, Map k v) insertLookupWithKey combine key value = Arrow.first getFirst . alterA doChange key where doChange Nothing = (First Nothing, Just value) doChange (Just oldValue) = (First (Just oldValue), Just (combine key value oldValue))
Maybe monoid returning the leftmost non-Nothing value.
is isomorphic to First
a
, but precedes it
historically.Alt
Maybe
a
>>>
getFirst (First (Just "hello") <> First Nothing <> First (Just "world"))
Just "hello"
Instances
Monad First # | |
Functor First # | |
MonadFix First # | Since: 4.8.0.0 |
Applicative First # | |
Foldable First # | Since: 4.8.0.0 |
fold :: Monoid m => First m -> m Source # foldMap :: Monoid m => (a -> m) -> First a -> m Source # foldr :: (a -> b -> b) -> b -> First a -> b Source # foldr' :: (a -> b -> b) -> b -> First a -> b Source # foldl :: (b -> a -> b) -> b -> First a -> b Source # foldl' :: (b -> a -> b) -> b -> First a -> b Source # foldr1 :: (a -> a -> a) -> First a -> a Source # foldl1 :: (a -> a -> a) -> First a -> a Source # toList :: First a -> [a] Source # null :: First a -> Bool Source # length :: First a -> Int Source # elem :: Eq a => a -> First a -> Bool Source # maximum :: Ord a => First a -> a Source # minimum :: Ord a => First a -> a Source # | |
Traversable First # | Since: 4.8.0.0 |
MonadZip First # | Since: 4.8.0.0 |
Eq a => Eq (First a) # | |
Data a => Data (First a) # | Since: 4.8.0.0 |
gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> First a -> c (First a) Source # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (First a) Source # toConstr :: First a -> Constr Source # dataTypeOf :: First a -> DataType Source # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (First a)) Source # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (First a)) Source # gmapT :: (forall b. Data b => b -> b) -> First a -> First a Source # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> First a -> r Source # gmapQr :: (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> First a -> r Source # gmapQ :: (forall d. Data d => d -> u) -> First a -> [u] Source # gmapQi :: Int -> (forall d. Data d => d -> u) -> First a -> u Source # gmapM :: Monad m => (forall d. Data d => d -> m d) -> First a -> m (First a) Source # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> First a -> m (First a) Source # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> First a -> m (First a) Source # | |
Ord a => Ord (First a) # | |
Read a => Read (First a) # | |
Show a => Show (First a) # | |
Generic (First a) # | |
Semigroup (First a) # | Since: 4.9.0.0 |
Monoid (First a) # | Since: 2.1 |
Generic1 First # | |
type Rep (First a) # | |
type Rep1 First # | |
Maybe monoid returning the rightmost non-Nothing value.
is isomorphic to Last
a
, and thus to
Dual
(First
a)Dual
(Alt
Maybe
a)
>>>
getLast (Last (Just "hello") <> Last Nothing <> Last (Just "world"))
Just "world"
Instances
Monad Last # | |
Functor Last # | |
MonadFix Last # | Since: 4.8.0.0 |
Applicative Last # | |
Foldable Last # | Since: 4.8.0.0 |
fold :: Monoid m => Last m -> m Source # foldMap :: Monoid m => (a -> m) -> Last a -> m Source # foldr :: (a -> b -> b) -> b -> Last a -> b Source # foldr' :: (a -> b -> b) -> b -> Last a -> b Source # foldl :: (b -> a -> b) -> b -> Last a -> b Source # foldl' :: (b -> a -> b) -> b -> Last a -> b Source # foldr1 :: (a -> a -> a) -> Last a -> a Source # foldl1 :: (a -> a -> a) -> Last a -> a Source # toList :: Last a -> [a] Source # null :: Last a -> Bool Source # length :: Last a -> Int Source # elem :: Eq a => a -> Last a -> Bool Source # maximum :: Ord a => Last a -> a Source # minimum :: Ord a => Last a -> a Source # | |
Traversable Last # | Since: 4.8.0.0 |
MonadZip Last # | Since: 4.8.0.0 |
Eq a => Eq (Last a) # | |
Data a => Data (Last a) # | Since: 4.8.0.0 |
gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Last a -> c (Last a) Source # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (Last a) Source # toConstr :: Last a -> Constr Source # dataTypeOf :: Last a -> DataType Source # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (Last a)) Source # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Last a)) Source # gmapT :: (forall b. Data b => b -> b) -> Last a -> Last a Source # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Last a -> r Source # gmapQr :: (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Last a -> r Source # gmapQ :: (forall d. Data d => d -> u) -> Last a -> [u] Source # gmapQi :: Int -> (forall d. Data d => d -> u) -> Last a -> u Source # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Last a -> m (Last a) Source # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Last a -> m (Last a) Source # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Last a -> m (Last a) Source # | |
Ord a => Ord (Last a) # | |
Read a => Read (Last a) # | |
Show a => Show (Last a) # | |
Generic (Last a) # | |
Semigroup (Last a) # | Since: 4.9.0.0 |
Monoid (Last a) # | Since: 2.1 |
Generic1 Last # | |
type Rep (Last a) # | |
type Rep1 Last # | |
Alternative
wrapper
Monoid under <|>
.
Since: 4.8.0.0
Instances
Generic1 (Alt f :: k -> *) # | |
Monad f => Monad (Alt f) # | |
Functor f => Functor (Alt f) # | |
MonadFix f => MonadFix (Alt f) # | Since: 4.8.0.0 |
Applicative f => Applicative (Alt f) # | |
MonadPlus f => MonadPlus (Alt f) # | |
Alternative f => Alternative (Alt f) # | |
MonadZip f => MonadZip (Alt f) # | Since: 4.8.0.0 |
Enum (f a) => Enum (Alt f a) # | |
succ :: Alt f a -> Alt f a Source # pred :: Alt f a -> Alt f a Source # toEnum :: Int -> Alt f a Source # fromEnum :: Alt f a -> Int Source # enumFrom :: Alt f a -> [Alt f a] Source # enumFromThen :: Alt f a -> Alt f a -> [Alt f a] Source # enumFromTo :: Alt f a -> Alt f a -> [Alt f a] Source # enumFromThenTo :: Alt f a -> Alt f a -> Alt f a -> [Alt f a] Source # | |
Eq (f a) => Eq (Alt f a) # | |
(Data (f a), Data a, Typeable f) => Data (Alt f a) # | Since: 4.8.0.0 |
gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Alt f a -> c (Alt f a) Source # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (Alt f a) Source # toConstr :: Alt f a -> Constr Source # dataTypeOf :: Alt f a -> DataType Source # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (Alt f a)) Source # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Alt f a)) Source # gmapT :: (forall b. Data b => b -> b) -> Alt f a -> Alt f a Source # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Alt f a -> r Source # gmapQr :: (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Alt f a -> r Source # gmapQ :: (forall d. Data d => d -> u) -> Alt f a -> [u] Source # gmapQi :: Int -> (forall d. Data d => d -> u) -> Alt f a -> u Source # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Alt f a -> m (Alt f a) Source # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Alt f a -> m (Alt f a) Source # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Alt f a -> m (Alt f a) Source # | |
Num (f a) => Num (Alt f a) # | |
Ord (f a) => Ord (Alt f a) # | |
Read (f a) => Read (Alt f a) # | |
Show (f a) => Show (Alt f a) # | |
Generic (Alt f a) # | |
Alternative f => Semigroup (Alt f a) # | Since: 4.9.0.0 |
Alternative f => Monoid (Alt f a) # | Since: 4.8.0.0 |
type Rep1 (Alt f :: k -> *) # | |
type Rep (Alt f a) # | |