Safe Haskell | Safe-Inferred |
---|---|
Language | Haskell2010 |
Data.Semigroup.Compat
Description
This backports the modern Data.Semigroup interface back to
base-4.9
/GHC 8.0.
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
Methods
(<>) :: 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 ByteArray # | Since: base-4.17.0.0 |
Semigroup Void # | Since: base-4.9.0.0 |
Semigroup All # | Since: base-4.9.0.0 |
Semigroup Any # | Since: base-4.9.0.0 |
Semigroup Ordering # | Since: base-4.9.0.0 |
Semigroup () # | Since: base-4.9.0.0 |
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 Methods (<>) :: 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 Methods (<>) :: 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 (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 Methods (<>) :: WrappedMonoid m -> WrappedMonoid m -> WrappedMonoid m # sconcat :: NonEmpty (WrappedMonoid m) -> WrappedMonoid m # stimes :: Integral b => b -> WrappedMonoid m -> WrappedMonoid m # | |
Semigroup (NonEmpty a) # | Since: base-4.9.0.0 |
Semigroup a => Semigroup (STM a) # | Since: base-4.17.0.0 |
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 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 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 a => Semigroup (IO a) # | Since: base-4.10.0.0 |
Semigroup a => Semigroup (Maybe a) # | Since: base-4.9.0.0 |
Semigroup a => Semigroup (Solo a) # | Since: base-4.15 |
Semigroup [a] # | 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 (Either a b) # | Since: base-4.9.0.0 |
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 {getMin = 3}
>>>
sconcat $ Min 1 :| [ Min n | n <- [2 .. 100]]
Min {getMin = 1}
Instances
Foldable1 Min # | Since: base-4.18.0.0 | ||||
Defined in Data.Foldable1 Methods 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 # | |||||
Applicative Min # | Since: base-4.9.0.0 | ||||
Functor Min # | Since: base-4.9.0.0 | ||||
Monad Min # | Since: base-4.9.0.0 | ||||
MonadFix Min # | Since: base-4.9.0.0 | ||||
Defined in Data.Semigroup | |||||
Foldable Min # | Since: base-4.9.0.0 | ||||
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 # elem :: Eq a => a -> Min a -> Bool # maximum :: Ord a => Min a -> a # | |||||
Traversable Min # | Since: base-4.9.0.0 | ||||
Generic1 Min # | |||||
Defined in Data.Semigroup Associated Types
| |||||
(Ord a, Bounded a) => Monoid (Min a) # | Since: base-4.9.0.0 | ||||
Ord a => Semigroup (Min a) # | Since: base-4.9.0.0 | ||||
Data a => Data (Min a) # | Since: base-4.9.0.0 | ||||
Defined in Data.Semigroup Methods 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) # | |||||
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) # | |||||
Defined in Data.Semigroup Associated Types
| |||||
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 {getMax = 42}
>>>
sconcat $ Max 1 :| [ Max n | n <- [2 .. 100]]
Max {getMax = 100}
Instances
Foldable1 Max # | Since: base-4.18.0.0 | ||||
Defined in Data.Foldable1 Methods 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 # | |||||
Applicative Max # | Since: base-4.9.0.0 | ||||
Functor Max # | Since: base-4.9.0.0 | ||||
Monad Max # | Since: base-4.9.0.0 | ||||
MonadFix Max # | Since: base-4.9.0.0 | ||||
Defined in Data.Semigroup | |||||
Foldable Max # | Since: base-4.9.0.0 | ||||
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 # elem :: Eq a => a -> Max a -> Bool # maximum :: Ord a => Max a -> a # | |||||
Traversable Max # | Since: base-4.9.0.0 | ||||
Generic1 Max # | |||||
Defined in Data.Semigroup Associated Types
| |||||
(Ord a, Bounded a) => Monoid (Max a) # | Since: base-4.9.0.0 | ||||
Ord a => Semigroup (Max a) # | Since: base-4.9.0.0 | ||||
Data a => Data (Max a) # | Since: base-4.9.0.0 | ||||
Defined in Data.Semigroup Methods 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) # | |||||
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) # | |||||
Defined in Data.Semigroup Associated Types
| |||||
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 {getFirst = 0}
>>>
sconcat $ First 1 :| [ First n | n <- [2 ..] ]
First {getFirst = 1}
Instances
Foldable1 First # | Since: base-4.18.0.0 | ||||
Defined in Data.Foldable1 Methods 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 # | |||||
Applicative First # | Since: base-4.9.0.0 | ||||
Functor First # | Since: base-4.9.0.0 | ||||
Monad First # | Since: base-4.9.0.0 | ||||
MonadFix First # | Since: base-4.9.0.0 | ||||
Defined in Data.Semigroup | |||||
Foldable First # | Since: base-4.9.0.0 | ||||
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 # elem :: Eq a => a -> First a -> Bool # maximum :: Ord a => First a -> a # minimum :: Ord a => First a -> a # | |||||
Traversable First # | Since: base-4.9.0.0 | ||||
Generic1 First # | |||||
Defined in Data.Semigroup Associated Types
| |||||
Semigroup (First a) # | Since: base-4.9.0.0 | ||||
Data a => Data (First a) # | Since: base-4.9.0.0 | ||||
Defined in Data.Semigroup Methods 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) # | |||||
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) # | |||||
Defined in Data.Semigroup Associated Types
| |||||
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..]]
* Hangs forever *
Instances
Foldable1 Last # | Since: base-4.18.0.0 | ||||
Defined in Data.Foldable1 Methods 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 # | |||||
Applicative Last # | Since: base-4.9.0.0 | ||||
Functor Last # | Since: base-4.9.0.0 | ||||
Monad Last # | Since: base-4.9.0.0 | ||||
MonadFix Last # | Since: base-4.9.0.0 | ||||
Defined in Data.Semigroup | |||||
Foldable Last # | Since: base-4.9.0.0 | ||||
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 # elem :: Eq a => a -> Last a -> Bool # maximum :: Ord a => Last a -> a # | |||||
Traversable Last # | Since: base-4.9.0.0 | ||||
Generic1 Last # | |||||
Defined in Data.Semigroup Associated Types
| |||||
Semigroup (Last a) # | Since: base-4.9.0.0 | ||||
Data a => Data (Last a) # | Since: base-4.9.0.0 | ||||
Defined in Data.Semigroup Methods 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) # | |||||
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) # | |||||
Defined in Data.Semigroup Associated Types
| |||||
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.
Constructors
WrapMonoid | |
Fields
|
Instances
Re-exported monoids from Data.Monoid
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
Foldable1 Dual # | Since: base-4.18.0.0 | ||||
Defined in Data.Foldable1 Methods 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 # | |||||
Applicative Dual # | Since: base-4.8.0.0 | ||||
Functor Dual # | Since: base-4.8.0.0 | ||||
Monad Dual # | Since: base-4.8.0.0 | ||||
Foldable Dual # | Since: base-4.8.0.0 | ||||
Defined in GHC.Internal.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 # elem :: Eq a => a -> Dual a -> Bool # maximum :: Ord a => Dual a -> a # | |||||
Traversable Dual # | Since: base-4.8.0.0 | ||||
Generic1 Dual # | |||||
Defined in GHC.Internal.Data.Semigroup.Internal Associated Types
| |||||
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) # | |||||
Defined in GHC.Internal.Data.Semigroup.Internal Associated Types
| |||||
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 | ||||
Defined in GHC.Internal.Data.Semigroup.Internal | |||||
type Rep1 Dual # | Since: base-4.7.0.0 | ||||
Defined in GHC.Internal.Data.Semigroup.Internal | |||||
type Rep (Dual a) # | Since: base-4.7.0.0 | ||||
Defined in GHC.Internal.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
Instances
Monoid (Endo a) # | Since: base-2.1 | ||||
Semigroup (Endo a) # | Since: base-4.9.0.0 | ||||
Generic (Endo a) # | |||||
Defined in GHC.Internal.Data.Semigroup.Internal Associated Types
| |||||
type Rep (Endo a) # | Since: base-4.7.0.0 | ||||
Defined in GHC.Internal.Data.Semigroup.Internal |
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}
Instances
Monoid All # | Since: base-2.1 | ||||
Semigroup All # | Since: base-4.9.0.0 | ||||
Bounded All # | Since: base-2.1 | ||||
Generic All # | |||||
Defined in GHC.Internal.Data.Semigroup.Internal Associated Types
| |||||
Read All # | Since: base-2.1 | ||||
Show All # | Since: base-2.1 | ||||
Eq All # | Since: base-2.1 | ||||
Ord All # | Since: base-2.1 | ||||
type Rep All # | Since: base-4.7.0.0 | ||||
Defined in GHC.Internal.Data.Semigroup.Internal |
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}
Instances
Monoid Any # | Since: base-2.1 | ||||
Semigroup Any # | Since: base-4.9.0.0 | ||||
Bounded Any # | Since: base-2.1 | ||||
Generic Any # | |||||
Defined in GHC.Internal.Data.Semigroup.Internal Associated Types
| |||||
Read Any # | Since: base-2.1 | ||||
Show Any # | Since: base-2.1 | ||||
Eq Any # | Since: base-2.1 | ||||
Ord Any # | Since: base-2.1 | ||||
type Rep Any # | Since: base-4.7.0.0 | ||||
Defined in GHC.Internal.Data.Semigroup.Internal |
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
Foldable1 Sum # | Since: base-4.18.0.0 | ||||
Defined in Data.Foldable1 Methods 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 # | |||||
Applicative Sum # | Since: base-4.8.0.0 | ||||
Functor Sum # | Since: base-4.8.0.0 | ||||
Monad Sum # | Since: base-4.8.0.0 | ||||
Foldable Sum # | Since: base-4.8.0.0 | ||||
Defined in GHC.Internal.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 # elem :: Eq a => a -> Sum a -> Bool # maximum :: Ord a => Sum a -> a # | |||||
Traversable Sum # | Since: base-4.8.0.0 | ||||
Generic1 Sum # | |||||
Defined in GHC.Internal.Data.Semigroup.Internal Associated Types
| |||||
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) # | |||||
Defined in GHC.Internal.Data.Semigroup.Internal Associated Types
| |||||
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 GHC.Internal.Data.Semigroup.Internal | |||||
type Rep (Sum a) # | Since: base-4.7.0.0 | ||||
Defined in GHC.Internal.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}
Constructors
Product | |
Fields
|
Instances
Foldable1 Product # | Since: base-4.18.0.0 | ||||
Defined in Data.Foldable1 Methods 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 # | |||||
Applicative Product # | Since: base-4.8.0.0 | ||||
Functor Product # | Since: base-4.8.0.0 | ||||
Monad Product # | Since: base-4.8.0.0 | ||||
Foldable Product # | Since: base-4.8.0.0 | ||||
Defined in GHC.Internal.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 # elem :: Eq a => a -> Product a -> Bool # maximum :: Ord a => Product a -> a # minimum :: Ord a => Product a -> a # | |||||
Traversable Product # | Since: base-4.8.0.0 | ||||
Generic1 Product # | |||||
Defined in GHC.Internal.Data.Semigroup.Internal Associated Types
| |||||
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) # | |||||
Defined in GHC.Internal.Data.Semigroup.Internal Associated Types
| |||||
Num a => Num (Product a) # | Since: base-4.7.0.0 | ||||
Defined in GHC.Internal.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 GHC.Internal.Data.Semigroup.Internal | |||||
type Rep1 Product # | Since: base-4.7.0.0 | ||||
Defined in GHC.Internal.Data.Semigroup.Internal | |||||
type Rep (Product a) # | Since: base-4.7.0.0 | ||||
Defined in GHC.Internal.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. In
the event of ties, the leftmost qualifying Arg
is chosen; contrast
with the behavior of minimum
and maximum
for many other types,
where ties are broken by considering elements to the left in the
structure to be less than elements to the right.
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)
Constructors
Arg | |
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 Methods bitraverse :: Applicative f => (a -> f c) -> (b -> f d) -> Arg a b -> f (Arg c d) # | |||||
Generic1 (Arg a :: Type -> Type) # | |||||
Defined in Data.Semigroup Associated Types
| |||||
Functor (Arg a) # | Since: base-4.9.0.0 | ||||
Foldable (Arg a) # | Since: base-4.9.0.0 | ||||
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 # 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 | ||||
(Data a, Data b) => Data (Arg a b) # | Since: base-4.9.0.0 | ||||
Defined in Data.Semigroup Methods 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) # | |||||
Defined in Data.Semigroup Associated Types
| |||||
(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) # | Note that
Since: base-4.9.0.0 | ||||
Ord a => Ord (Arg a b) # | Note that 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-4.21.0.0-a5ba" '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-4.21.0.0-a5ba" '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))) |