Safe Haskell | Safe-Inferred |
---|---|
Language | Haskell2010 |
Synopsis
- class Semigroup a where
- stimesMonoid :: (Integral b, Monoid a) => b -> a -> a
- stimesIdempotent :: Integral b => b -> a -> a
- stimesIdempotentMonoid :: (Integral b, Monoid a) => b -> a -> a
- mtimesDefault :: (Integral b, Monoid a) => b -> a -> a
- newtype Min a = Min {
- getMin :: a
- newtype Max a = Max {
- getMax :: a
- newtype First a = First {
- getFirst :: a
- newtype Last a = Last {
- getLast :: a
- newtype WrappedMonoid m = WrapMonoid {
- unwrapMonoid :: m
- 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
- diff :: Semigroup m => m -> Endo m
- cycle1 :: Semigroup m => m -> m
- data Arg a b = Arg a b
- type ArgMin a b = Min (Arg a b)
- type ArgMax a b = Max (Arg a b)
Documentation
The class of semigroups (types with an associative binary operation).
Instances should satisfy the following:
You can alternatively define sconcat
instead of (<>
), in which case the
laws are:
Since: base-4.9.0.0
(<>) :: a -> a -> a infixr 6 #
An associative operation.
Examples
>>>
[1,2,3] <> [4,5,6]
[1,2,3,4,5,6]
>>>
Just [1, 2, 3] <> Just [4, 5, 6]
Just [1,2,3,4,5,6]
>>>
putStr "Hello, " <> putStrLn "World!"
Hello, World!
Reduce a non-empty list with <>
The default definition should be sufficient, but this can be overridden for efficiency.
Examples
For the following examples, we will assume that we have:
>>>
import Data.List.NonEmpty (NonEmpty (..))
>>>
sconcat $ "Hello" :| [" ", "Haskell", "!"]
"Hello Haskell!"
>>>
sconcat $ Just [1, 2, 3] :| [Nothing, Just [4, 5, 6]]
Just [1,2,3,4,5,6]
>>>
sconcat $ Left 1 :| [Right 2, Left 3, Right 4]
Right 2
stimes :: Integral b => b -> a -> a #
Repeat a value n
times.
The default definition will raise an exception for a multiplier that is <= 0
.
This may be overridden with an implementation that is total. For monoids
it is preferred to use stimesMonoid
.
By making this a member of the class, idempotent semigroups
and monoids can upgrade this to execute in \(\mathcal{O}(1)\) by
picking stimes =
or stimesIdempotent
stimes =
respectively.stimesIdempotentMonoid
Examples
>>>
stimes 4 [1]
[1,1,1,1]
>>>
stimes 5 (putStr "hi!")
hi!hi!hi!hi!hi!
>>>
stimes 3 (Right ":)")
Right ":)"
Instances
Semigroup All | Since: base-4.9.0.0 |
Semigroup Any | Since: base-4.9.0.0 |
Semigroup Void | Since: base-4.9.0.0 |
Semigroup Ordering | Since: base-4.9.0.0 |
Semigroup () | Since: base-4.9.0.0 |
Bits a => Semigroup (And a) | Since: base-4.16 |
FiniteBits a => Semigroup (Iff a) | This constraint is arguably
too strong. However, as some types (such as Since: base-4.16 |
Bits a => Semigroup (Ior a) | Since: base-4.16 |
Bits a => Semigroup (Xor a) | Since: base-4.16 |
Semigroup (FromMaybe b) | |
Semigroup a => Semigroup (JoinWith a) | |
Semigroup (NonEmptyDList a) | |
Semigroup (Comparison a) |
(<>) :: Comparison a -> Comparison a -> Comparison a Comparison cmp <> Comparison cmp' = Comparison a a' -> cmp a a' <> cmp a a' |
Defined in Data.Functor.Contravariant (<>) :: Comparison a -> Comparison a -> Comparison a # sconcat :: NonEmpty (Comparison a) -> Comparison a # stimes :: Integral b => b -> Comparison a -> Comparison a # | |
Semigroup (Equivalence a) |
(<>) :: Equivalence a -> Equivalence a -> Equivalence a Equivalence equiv <> Equivalence equiv' = Equivalence a b -> equiv a b && equiv' a b |
Defined in Data.Functor.Contravariant (<>) :: Equivalence a -> Equivalence a -> Equivalence a # sconcat :: NonEmpty (Equivalence a) -> Equivalence a # stimes :: Integral b => b -> Equivalence a -> Equivalence a # | |
Semigroup (Predicate a) |
(<>) :: Predicate a -> Predicate a -> Predicate a Predicate pred <> Predicate pred' = Predicate a -> pred a && pred' a |
Semigroup a => Semigroup (Identity a) | Since: base-4.9.0.0 |
Semigroup (First a) | Since: base-4.9.0.0 |
Semigroup (Last a) | Since: base-4.9.0.0 |
Semigroup (First a) | Since: base-4.9.0.0 |
Semigroup (Last a) | Since: base-4.9.0.0 |
Ord a => Semigroup (Max a) | Since: base-4.9.0.0 |
Ord a => Semigroup (Min a) | Since: base-4.9.0.0 |
Monoid m => Semigroup (WrappedMonoid m) | Since: base-4.9.0.0 |
Defined in Data.Semigroup (<>) :: WrappedMonoid m -> WrappedMonoid m -> WrappedMonoid m # sconcat :: NonEmpty (WrappedMonoid m) -> WrappedMonoid m # stimes :: Integral b => b -> WrappedMonoid m -> WrappedMonoid m # | |
Semigroup a => Semigroup (Dual a) | Since: base-4.9.0.0 |
Semigroup (Endo a) | Since: base-4.9.0.0 |
Num a => Semigroup (Product a) | Since: base-4.9.0.0 |
Num a => Semigroup (Sum a) | Since: base-4.9.0.0 |
Semigroup (NonEmpty a) | Since: base-4.9.0.0 |
Semigroup a => Semigroup (STM a) | Since: base-4.17.0.0 |
Semigroup a => Semigroup (IO a) | Since: base-4.10.0.0 |
Semigroup a => Semigroup (Maybe a) | Since: base-4.9.0.0 |
Semigroup a => Semigroup (a) | Since: base-4.15 |
Semigroup [a] | Since: base-4.9.0.0 |
Semigroup (Either a b) | Since: base-4.9.0.0 |
Semigroup a => Semigroup (Op a b) |
(<>) :: Op a b -> Op a b -> Op a b Op f <> Op g = Op a -> f a <> g a |
Semigroup (Proxy s) | Since: base-4.9.0.0 |
Semigroup a => Semigroup (ST s a) | Since: base-4.11.0.0 |
(Semigroup a, Semigroup b) => Semigroup (a, b) | Since: base-4.9.0.0 |
Semigroup b => Semigroup (a -> b) | Since: base-4.9.0.0 |
Semigroup a => Semigroup (Const a b) | Since: base-4.9.0.0 |
(Applicative f, Semigroup a) => Semigroup (Ap f a) | Since: base-4.12.0.0 |
Alternative f => Semigroup (Alt f a) | Since: base-4.9.0.0 |
(Semigroup a, Semigroup b, Semigroup c) => Semigroup (a, b, c) | Since: base-4.9.0.0 |
(Semigroup (f a), Semigroup (g a)) => Semigroup (Product f g a) | Since: base-4.16.0.0 |
(Semigroup a, Semigroup b, Semigroup c, Semigroup d) => Semigroup (a, b, c, d) | Since: base-4.9.0.0 |
Semigroup (f (g a)) => Semigroup (Compose f g a) | Since: base-4.16.0.0 |
(Semigroup a, Semigroup b, Semigroup c, Semigroup d, Semigroup e) => Semigroup (a, b, c, d, e) | Since: base-4.9.0.0 |
stimesMonoid :: (Integral b, Monoid a) => b -> a -> a #
stimesIdempotent :: Integral b => b -> a -> a #
stimesIdempotentMonoid :: (Integral b, Monoid a) => b -> a -> a #
mtimesDefault :: (Integral b, Monoid a) => b -> a -> a #
Repeat a value n
times.
mtimesDefault n a = a <> a <> ... <> a -- using <> (n-1) times
In many cases,
for a stimes
0 aMonoid
will produce mempty
.
However, there are situations when it cannot do so. In particular,
the following situation is fairly common:
data T a = ... class Constraint1 a class Constraint1 a => Constraint2 a
instance Constraint1 a =>Semigroup
(T a) instance Constraint2 a =>Monoid
(T a)
Since Constraint1
is insufficient to implement mempty
,
stimes
for T a
cannot do so.
When working with such a type, or when working polymorphically with
Semigroup
instances, mtimesDefault
should be used when the
multiplier might be zero. It is implemented using stimes
when
the multiplier is nonzero and mempty
when it is zero.
Examples
>>>
mtimesDefault 0 "bark"
[]
>>>
mtimesDefault 3 "meow"
"meowmeowmeow"
Semigroups
The Min
Monoid
and Semigroup
always choose the smaller element as
by the Ord
instance and min
of the contained type.
Examples
>>>
Min 42 <> Min 3
Min 3
>>>
sconcat $ Min 1 :| [ Min n | n <- [2 .. 100]]
Min {getMin = 1}
Instances
MonadFix Min | Since: base-4.9.0.0 |
Defined in Data.Semigroup | |
Foldable Min | Since: base-4.9.0.0 |
Defined in Data.Semigroup 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 # elem :: Eq a => a -> Min a -> Bool # maximum :: Ord a => Min a -> a # | |
Foldable1 Min | Since: base-4.18.0.0 |
Defined in Data.Foldable1 fold1 :: Semigroup m => Min m -> m # foldMap1 :: Semigroup m => (a -> m) -> Min a -> m # foldMap1' :: Semigroup m => (a -> m) -> Min a -> m # toNonEmpty :: Min a -> NonEmpty a # maximum :: Ord a => Min a -> a # minimum :: Ord a => Min a -> a # foldrMap1 :: (a -> b) -> (a -> b -> b) -> Min a -> b # foldlMap1' :: (a -> b) -> (b -> a -> b) -> Min a -> b # foldlMap1 :: (a -> b) -> (b -> a -> b) -> Min a -> b # foldrMap1' :: (a -> b) -> (a -> b -> b) -> Min a -> b # | |
Traversable Min | Since: base-4.9.0.0 |
Applicative Min | Since: base-4.9.0.0 |
Functor Min | Since: base-4.9.0.0 |
Monad Min | Since: base-4.9.0.0 |
Generic1 Min | |
Data a => Data (Min a) | Since: base-4.9.0.0 |
Defined in Data.Semigroup gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Min a -> c (Min a) # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (Min a) # dataTypeOf :: Min a -> DataType # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (Min a)) # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Min a)) # gmapT :: (forall b. Data b => b -> b) -> Min a -> Min a # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Min a -> r # gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Min a -> r # gmapQ :: (forall d. Data d => d -> u) -> Min a -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> Min a -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Min a -> m (Min a) # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Min a -> m (Min a) # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Min a -> m (Min a) # | |
(Ord a, Bounded a) => Monoid (Min a) | Since: base-4.9.0.0 |
Ord a => Semigroup (Min a) | Since: base-4.9.0.0 |
Bounded a => Bounded (Min a) | Since: base-4.9.0.0 |
Enum a => Enum (Min a) | Since: base-4.9.0.0 |
Generic (Min a) | |
Num a => Num (Min a) | Since: base-4.9.0.0 |
Read a => Read (Min a) | Since: base-4.9.0.0 |
Show a => Show (Min a) | Since: base-4.9.0.0 |
Eq a => Eq (Min a) | Since: base-4.9.0.0 |
Ord a => Ord (Min a) | Since: base-4.9.0.0 |
type Rep1 Min | Since: base-4.9.0.0 |
Defined in Data.Semigroup | |
type Rep (Min a) | Since: base-4.9.0.0 |
Defined in Data.Semigroup |
The Max
Monoid
and Semigroup
always choose the bigger element as
by the Ord
instance and max
of the contained type.
Examples
>>>
Max 42 <> Max 3
Max 42
>>>
sconcat $ Max 1 :| [ Max n | n <- [2 .. 100]]
Max {getMax = 100}
Instances
MonadFix Max | Since: base-4.9.0.0 |
Defined in Data.Semigroup | |
Foldable Max | Since: base-4.9.0.0 |
Defined in Data.Semigroup 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 # elem :: Eq a => a -> Max a -> Bool # maximum :: Ord a => Max a -> a # | |
Foldable1 Max | Since: base-4.18.0.0 |
Defined in Data.Foldable1 fold1 :: Semigroup m => Max m -> m # foldMap1 :: Semigroup m => (a -> m) -> Max a -> m # foldMap1' :: Semigroup m => (a -> m) -> Max a -> m # toNonEmpty :: Max a -> NonEmpty a # maximum :: Ord a => Max a -> a # minimum :: Ord a => Max a -> a # foldrMap1 :: (a -> b) -> (a -> b -> b) -> Max a -> b # foldlMap1' :: (a -> b) -> (b -> a -> b) -> Max a -> b # foldlMap1 :: (a -> b) -> (b -> a -> b) -> Max a -> b # foldrMap1' :: (a -> b) -> (a -> b -> b) -> Max a -> b # | |
Traversable Max | Since: base-4.9.0.0 |
Applicative Max | Since: base-4.9.0.0 |
Functor Max | Since: base-4.9.0.0 |
Monad Max | Since: base-4.9.0.0 |
Generic1 Max | |
Data a => Data (Max a) | Since: base-4.9.0.0 |
Defined in Data.Semigroup gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Max a -> c (Max a) # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (Max a) # dataTypeOf :: Max a -> DataType # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (Max a)) # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Max a)) # gmapT :: (forall b. Data b => b -> b) -> Max a -> Max a # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Max a -> r # gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Max a -> r # gmapQ :: (forall d. Data d => d -> u) -> Max a -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> Max a -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Max a -> m (Max a) # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Max a -> m (Max a) # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Max a -> m (Max a) # | |
(Ord a, Bounded a) => Monoid (Max a) | Since: base-4.9.0.0 |
Ord a => Semigroup (Max a) | Since: base-4.9.0.0 |
Bounded a => Bounded (Max a) | Since: base-4.9.0.0 |
Enum a => Enum (Max a) | Since: base-4.9.0.0 |
Generic (Max a) | |
Num a => Num (Max a) | Since: base-4.9.0.0 |
Read a => Read (Max a) | Since: base-4.9.0.0 |
Show a => Show (Max a) | Since: base-4.9.0.0 |
Eq a => Eq (Max a) | Since: base-4.9.0.0 |
Ord a => Ord (Max a) | Since: base-4.9.0.0 |
type Rep1 Max | Since: base-4.9.0.0 |
Defined in Data.Semigroup | |
type Rep (Max a) | Since: base-4.9.0.0 |
Defined in Data.Semigroup |
Beware that Data.Semigroup.
First
is different from
Data.Monoid.
First
. The former simply returns the first value,
so Data.Semigroup.First Nothing <> x = Data.Semigroup.First Nothing
.
The latter returns the first non-Nothing
,
thus Data.Monoid.First Nothing <> x = x
.
Examples
>>>
First 0 <> First 10
First 0
>>>
sconcat $ First 1 :| [ First n | n <- [2 ..] ]
First 1
Instances
MonadFix First | Since: base-4.9.0.0 |
Defined in Data.Semigroup | |
Foldable First | Since: base-4.9.0.0 |
Defined in Data.Semigroup 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 # elem :: Eq a => a -> First a -> Bool # maximum :: Ord a => First a -> a # minimum :: Ord a => First a -> a # | |
Foldable1 First | Since: base-4.18.0.0 |
Defined in Data.Foldable1 fold1 :: Semigroup m => First m -> m # foldMap1 :: Semigroup m => (a -> m) -> First a -> m # foldMap1' :: Semigroup m => (a -> m) -> First a -> m # toNonEmpty :: First a -> NonEmpty a # maximum :: Ord a => First a -> a # minimum :: Ord a => First a -> a # foldrMap1 :: (a -> b) -> (a -> b -> b) -> First a -> b # foldlMap1' :: (a -> b) -> (b -> a -> b) -> First a -> b # foldlMap1 :: (a -> b) -> (b -> a -> b) -> First a -> b # foldrMap1' :: (a -> b) -> (a -> b -> b) -> First a -> b # | |
Traversable First | Since: base-4.9.0.0 |
Applicative First | Since: base-4.9.0.0 |
Functor First | Since: base-4.9.0.0 |
Monad First | Since: base-4.9.0.0 |
Generic1 First | |
Data a => Data (First a) | Since: base-4.9.0.0 |
Defined in Data.Semigroup gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> First a -> c (First a) # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (First a) # toConstr :: First a -> Constr # dataTypeOf :: First a -> DataType # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (First a)) # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (First a)) # gmapT :: (forall b. Data b => b -> b) -> First a -> First a # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> First a -> r # gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> First a -> r # gmapQ :: (forall d. Data d => d -> u) -> First a -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> First a -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> First a -> m (First a) # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> First a -> m (First a) # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> First a -> m (First a) # | |
Semigroup (First a) | Since: base-4.9.0.0 |
Bounded a => Bounded (First a) | Since: base-4.9.0.0 |
Enum a => Enum (First a) | Since: base-4.9.0.0 |
Generic (First a) | |
Read a => Read (First a) | Since: base-4.9.0.0 |
Show a => Show (First a) | Since: base-4.9.0.0 |
Eq a => Eq (First a) | Since: base-4.9.0.0 |
Ord a => Ord (First a) | Since: base-4.9.0.0 |
type Rep1 First | Since: base-4.9.0.0 |
Defined in Data.Semigroup | |
type Rep (First a) | Since: base-4.9.0.0 |
Defined in Data.Semigroup |
Beware that Data.Semigroup.
Last
is different from
Data.Monoid.
Last
. The former simply returns the last value,
so x <> Data.Semigroup.Last Nothing = Data.Semigroup.Last Nothing
.
The latter returns the last non-Nothing
,
thus x <> Data.Monoid.Last Nothing = x
.
Examples
>>>
Last 0 <> Last 10
Last {getLast = 10}
>>>
sconcat $ Last 1 :| [ Last n | n <- [2..]]
Last {getLast = * hangs forever *
Instances
MonadFix Last | Since: base-4.9.0.0 |
Defined in Data.Semigroup | |
Foldable Last | Since: base-4.9.0.0 |
Defined in Data.Semigroup 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 # elem :: Eq a => a -> Last a -> Bool # maximum :: Ord a => Last a -> a # | |
Foldable1 Last | Since: base-4.18.0.0 |
Defined in Data.Foldable1 fold1 :: Semigroup m => Last m -> m # foldMap1 :: Semigroup m => (a -> m) -> Last a -> m # foldMap1' :: Semigroup m => (a -> m) -> Last a -> m # toNonEmpty :: Last a -> NonEmpty a # maximum :: Ord a => Last a -> a # minimum :: Ord a => Last a -> a # foldrMap1 :: (a -> b) -> (a -> b -> b) -> Last a -> b # foldlMap1' :: (a -> b) -> (b -> a -> b) -> Last a -> b # foldlMap1 :: (a -> b) -> (b -> a -> b) -> Last a -> b # foldrMap1' :: (a -> b) -> (a -> b -> b) -> Last a -> b # | |
Traversable Last | Since: base-4.9.0.0 |
Applicative Last | Since: base-4.9.0.0 |
Functor Last | Since: base-4.9.0.0 |
Monad Last | Since: base-4.9.0.0 |
Generic1 Last | |
Data a => Data (Last a) | Since: base-4.9.0.0 |
Defined in Data.Semigroup gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Last a -> c (Last a) # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (Last a) # toConstr :: Last a -> Constr # dataTypeOf :: Last a -> DataType # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (Last a)) # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Last a)) # gmapT :: (forall b. Data b => b -> b) -> Last a -> Last a # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Last a -> r # gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Last a -> r # gmapQ :: (forall d. Data d => d -> u) -> Last a -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> Last a -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Last a -> m (Last a) # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Last a -> m (Last a) # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Last a -> m (Last a) # | |
Semigroup (Last a) | Since: base-4.9.0.0 |
Bounded a => Bounded (Last a) | Since: base-4.9.0.0 |
Enum a => Enum (Last a) | Since: base-4.9.0.0 |
Defined in Data.Semigroup | |
Generic (Last a) | |
Read a => Read (Last a) | Since: base-4.9.0.0 |
Show a => Show (Last a) | Since: base-4.9.0.0 |
Eq a => Eq (Last a) | Since: base-4.9.0.0 |
Ord a => Ord (Last a) | Since: base-4.9.0.0 |
type Rep1 Last | Since: base-4.9.0.0 |
Defined in Data.Semigroup | |
type Rep (Last a) | Since: base-4.9.0.0 |
Defined in Data.Semigroup |
newtype WrappedMonoid m #
Provide a Semigroup for an arbitrary Monoid.
NOTE: This is not needed anymore since Semigroup
became a superclass of
Monoid
in base-4.11 and this newtype be deprecated at some point in the future.
WrapMonoid | |
|
Instances
Re-exported monoids from Data.Monoid
The dual of a Monoid
, obtained by swapping the arguments of mappend
.
| The dual of a Monoid
, obtained by swapping the arguments of (<>)
.
Dual a <> Dual b == Dual (b <> a)
Examples
>>>
Dual "Hello" <> Dual "World"
Dual {getDual = "WorldHello"}
>>>
Dual (Dual "Hello") <> Dual (Dual "World")
Dual {getDual = Dual {getDual = "HelloWorld"}}
Instances
Foldable Dual | Since: base-4.8.0.0 |
Defined in Data.Foldable 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 # elem :: Eq a => a -> Dual a -> Bool # maximum :: Ord a => Dual a -> a # | |
Foldable1 Dual | Since: base-4.18.0.0 |
Defined in Data.Foldable1 fold1 :: Semigroup m => Dual m -> m # foldMap1 :: Semigroup m => (a -> m) -> Dual a -> m # foldMap1' :: Semigroup m => (a -> m) -> Dual a -> m # toNonEmpty :: Dual a -> NonEmpty a # maximum :: Ord a => Dual a -> a # minimum :: Ord a => Dual a -> a # foldrMap1 :: (a -> b) -> (a -> b -> b) -> Dual a -> b # foldlMap1' :: (a -> b) -> (b -> a -> b) -> Dual a -> b # foldlMap1 :: (a -> b) -> (b -> a -> b) -> Dual a -> b # foldrMap1' :: (a -> b) -> (a -> b -> b) -> Dual a -> b # | |
Traversable Dual | Since: base-4.8.0.0 |
Applicative Dual | Since: base-4.8.0.0 |
Functor Dual | Since: base-4.8.0.0 |
Monad Dual | Since: base-4.8.0.0 |
Generic1 Dual | |
Monoid a => Monoid (Dual a) | Since: base-2.1 |
Semigroup a => Semigroup (Dual a) | Since: base-4.9.0.0 |
Bounded a => Bounded (Dual a) | Since: base-2.1 |
Generic (Dual a) | |
Read a => Read (Dual a) | Since: base-2.1 |
Show a => Show (Dual a) | Since: base-2.1 |
Eq a => Eq (Dual a) | Since: base-2.1 |
Ord a => Ord (Dual a) | Since: base-2.1 |
type Rep1 Dual | Since: base-4.7.0.0 |
Defined in Data.Semigroup.Internal | |
type Rep (Dual a) | Since: base-4.7.0.0 |
Defined in Data.Semigroup.Internal |
The monoid of endomorphisms under composition.
Endo f <> Endo g == Endo (f . g)
Examples
>>>
let computation = Endo ("Hello, " ++) <> Endo (++ "!")
>>>
appEndo computation "Haskell"
"Hello, Haskell!"
>>>
let computation = Endo (*3) <> Endo (+1)
>>>
appEndo computation 1
6
Boolean monoid under conjunction (&&)
.
All x <> All y = All (x && y)
Examples
>>>
All True <> mempty <> All False)
All {getAll = False}
>>>
mconcat (map (\x -> All (even x)) [2,4,6,7,8])
All {getAll = False}
>>>
All True <> mempty
All {getAll = True}
Boolean monoid under disjunction (||)
.
Any x <> Any y = Any (x || y)
Examples
>>>
Any True <> mempty <> Any False
Any {getAny = True}
>>>
mconcat (map (\x -> Any (even x)) [2,4,6,7,8])
Any {getAny = True}
>>>
Any False <> mempty
Any {getAny = False}
Monoid under addition.
Sum a <> Sum b = Sum (a + b)
Examples
>>>
Sum 1 <> Sum 2 <> mempty
Sum {getSum = 3}
>>>
mconcat [ Sum n | n <- [3 .. 9]]
Sum {getSum = 42}
Instances
Foldable Sum | Since: base-4.8.0.0 |
Defined in Data.Foldable 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 # elem :: Eq a => a -> Sum a -> Bool # maximum :: Ord a => Sum a -> a # | |
Foldable1 Sum | Since: base-4.18.0.0 |
Defined in Data.Foldable1 fold1 :: Semigroup m => Sum m -> m # foldMap1 :: Semigroup m => (a -> m) -> Sum a -> m # foldMap1' :: Semigroup m => (a -> m) -> Sum a -> m # toNonEmpty :: Sum a -> NonEmpty a # maximum :: Ord a => Sum a -> a # minimum :: Ord a => Sum a -> a # foldrMap1 :: (a -> b) -> (a -> b -> b) -> Sum a -> b # foldlMap1' :: (a -> b) -> (b -> a -> b) -> Sum a -> b # foldlMap1 :: (a -> b) -> (b -> a -> b) -> Sum a -> b # foldrMap1' :: (a -> b) -> (a -> b -> b) -> Sum a -> b # | |
Traversable Sum | Since: base-4.8.0.0 |
Applicative Sum | Since: base-4.8.0.0 |
Functor Sum | Since: base-4.8.0.0 |
Monad Sum | Since: base-4.8.0.0 |
Generic1 Sum | |
Num a => Monoid (Sum a) | Since: base-2.1 |
Num a => Semigroup (Sum a) | Since: base-4.9.0.0 |
Bounded a => Bounded (Sum a) | Since: base-2.1 |
Generic (Sum a) | |
Num a => Num (Sum a) | Since: base-4.7.0.0 |
Read a => Read (Sum a) | Since: base-2.1 |
Show a => Show (Sum a) | Since: base-2.1 |
Eq a => Eq (Sum a) | Since: base-2.1 |
Ord a => Ord (Sum a) | Since: base-2.1 |
type Rep1 Sum | Since: base-4.7.0.0 |
Defined in Data.Semigroup.Internal | |
type Rep (Sum a) | Since: base-4.7.0.0 |
Defined in Data.Semigroup.Internal |
Monoid under multiplication.
Product x <> Product y == Product (x * y)
Examples
>>>
Product 3 <> Product 4 <> mempty
Product {getProduct = 12}
>>>
mconcat [ Product n | n <- [2 .. 10]]
Product {getProduct = 3628800}
Product | |
|
Instances
Foldable Product | Since: base-4.8.0.0 |
Defined in Data.Foldable 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 # elem :: Eq a => a -> Product a -> Bool # maximum :: Ord a => Product a -> a # minimum :: Ord a => Product a -> a # | |
Foldable1 Product | Since: base-4.18.0.0 |
Defined in Data.Foldable1 fold1 :: Semigroup m => Product m -> m # foldMap1 :: Semigroup m => (a -> m) -> Product a -> m # foldMap1' :: Semigroup m => (a -> m) -> Product a -> m # toNonEmpty :: Product a -> NonEmpty a # maximum :: Ord a => Product a -> a # minimum :: Ord a => Product a -> a # foldrMap1 :: (a -> b) -> (a -> b -> b) -> Product a -> b # foldlMap1' :: (a -> b) -> (b -> a -> b) -> Product a -> b # foldlMap1 :: (a -> b) -> (b -> a -> b) -> Product a -> b # foldrMap1' :: (a -> b) -> (a -> b -> b) -> Product a -> b # | |
Traversable Product | Since: base-4.8.0.0 |
Applicative Product | Since: base-4.8.0.0 |
Functor Product | Since: base-4.8.0.0 |
Monad Product | Since: base-4.8.0.0 |
Generic1 Product | |
Num a => Monoid (Product a) | Since: base-2.1 |
Num a => Semigroup (Product a) | Since: base-4.9.0.0 |
Bounded a => Bounded (Product a) | Since: base-2.1 |
Generic (Product a) | |
Num a => Num (Product a) | Since: base-4.7.0.0 |
Defined in Data.Semigroup.Internal | |
Read a => Read (Product a) | Since: base-2.1 |
Show a => Show (Product a) | Since: base-2.1 |
Eq a => Eq (Product a) | Since: base-2.1 |
Ord a => Ord (Product a) | Since: base-2.1 |
Defined in Data.Semigroup.Internal | |
type Rep1 Product | Since: base-4.7.0.0 |
Defined in Data.Semigroup.Internal | |
type Rep (Product a) | Since: base-4.7.0.0 |
Defined in Data.Semigroup.Internal |
Difference lists of a semigroup
diff :: Semigroup m => m -> Endo m #
This lets you use a difference list of a Semigroup
as a Monoid
.
Examples
let hello = diff "Hello, "
>>>
appEndo hello "World!"
"Hello, World!"
>>>
appEndo (hello <> mempty) "World!"
"Hello, World!"
>>>
appEndo (mempty <> hello) "World!"
"Hello, World!"
let world = diff "World" let excl = diff "!"
>>>
appEndo (hello <> (world <> excl)) mempty
"Hello, World!"
>>>
appEndo ((hello <> world) <> excl) mempty
"Hello, World!"
ArgMin, ArgMax
Arg
isn't itself a Semigroup
in its own right, but it can be
placed inside Min
and Max
to compute an arg min or arg max.
Examples
>>>
minimum [ Arg (x * x) x | x <- [-10 .. 10] ]
Arg 0 0
>>>
maximum [ Arg (-0.2*x^2 + 1.5*x + 1) x | x <- [-10 .. 10] ]
Arg 3.8 4.0
>>>
minimum [ Arg (-0.2*x^2 + 1.5*x + 1) x | x <- [-10 .. 10] ]
Arg (-34.0) (-10.0)
Instances
Bifoldable Arg | Since: base-4.10.0.0 |
Bifoldable1 Arg | |
Defined in Data.Bifoldable1 | |
Bifunctor Arg | Since: base-4.9.0.0 |
Bitraversable Arg | Since: base-4.10.0.0 |
Defined in Data.Semigroup bitraverse :: Applicative f => (a -> f c) -> (b -> f d) -> Arg a b -> f (Arg c d) # | |
Generic1 (Arg a :: Type -> Type) | |
Foldable (Arg a) | Since: base-4.9.0.0 |
Defined in Data.Semigroup 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 # elem :: Eq a0 => a0 -> Arg a a0 -> Bool # maximum :: Ord a0 => Arg a a0 -> a0 # minimum :: Ord a0 => Arg a a0 -> a0 # | |
Traversable (Arg a) | Since: base-4.9.0.0 |
Functor (Arg a) | Since: base-4.9.0.0 |
(Data a, Data b) => Data (Arg a b) | Since: base-4.9.0.0 |
Defined in Data.Semigroup gfoldl :: (forall d b0. Data d => c (d -> b0) -> d -> c b0) -> (forall g. g -> c g) -> Arg a b -> c (Arg a b) # gunfold :: (forall b0 r. Data b0 => c (b0 -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (Arg a b) # toConstr :: Arg a b -> Constr # dataTypeOf :: Arg a b -> DataType # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (Arg a b)) # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Arg a b)) # gmapT :: (forall b0. Data b0 => b0 -> b0) -> Arg a b -> Arg a b # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Arg a b -> r # gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Arg a b -> r # gmapQ :: (forall d. Data d => d -> u) -> Arg a b -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> Arg a b -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Arg a b -> m (Arg a b) # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Arg a b -> m (Arg a b) # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Arg a b -> m (Arg a b) # | |
Generic (Arg a b) | |
(Read a, Read b) => Read (Arg a b) | Since: base-4.9.0.0 |
(Show a, Show b) => Show (Arg a b) | Since: base-4.9.0.0 |
Eq a => Eq (Arg a b) | Since: base-4.9.0.0 |
Ord a => Ord (Arg a b) | Since: base-4.9.0.0 |
type Rep1 (Arg a :: Type -> Type) | Since: base-4.9.0.0 |
Defined in Data.Semigroup type Rep1 (Arg a :: Type -> Type) = D1 ('MetaData "Arg" "Data.Semigroup" "base" 'False) (C1 ('MetaCons "Arg" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 a) :*: S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) Par1)) | |
type Rep (Arg a b) | Since: base-4.9.0.0 |
Defined in Data.Semigroup type Rep (Arg a b) = D1 ('MetaData "Arg" "Data.Semigroup" "base" 'False) (C1 ('MetaCons "Arg" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 a) :*: S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 b))) |