Safe Haskell	Safe-Inferred
Language	Haskell2010

Data.Monoid.RightAction.Coproduct

Synopsis

newtype m :+: n = Coproduct {
- getCoproduct :: Seq (Either m n)
}
inL :: m -> m :+: n
inR :: n -> m :+: n
normaliseCoproduct :: (Semigroup m, Semigroup n) => (m :+: n) -> [Either m n]

Documentation

newtype m :+: n Source #

The coproduct of two monoids is a monoid that can contain values of either constituent.

This is useful if you have two different actions on the same state type, and want to combine them.

Note: The multiplication of this monoid is formal, so the same semantic values may have differing representations. Therefore it's not advised to inspect the contents of a coproduct. You should usually want to use normaliseCoproduct.

Constructors

Coproduct
Fields getCoproduct :: Seq (Either m n)

Instances

Instances details

Monoid (m :+: n) Source #
Instance details Defined in Data.Monoid.RightAction.Coproduct Methods mempty :: m :+: n # mappend :: (m :+: n) -> (m :+: n) -> m :+: n # mconcat :: [m :+: n] -> m :+: n #
Semigroup (m :+: n) Source #
Instance details Defined in Data.Monoid.RightAction.Coproduct Methods (<>) :: (m :+: n) -> (m :+: n) -> m :+: n # sconcat :: NonEmpty (m :+: n) -> m :+: n # stimes :: Integral b => b -> (m :+: n) -> m :+: n #
(Eq m, Eq n, Semigroup m, Semigroup n) => Eq (m :+: n) Source #	Coproducts are compared after normalising
Instance details Defined in Data.Monoid.RightAction.Coproduct Methods (==) :: (m :+: n) -> (m :+: n) -> Bool # (/=) :: (m :+: n) -> (m :+: n) -> Bool #
(RightAction m s, RightAction n s) => RightAction (m :+: n) s Source #
Instance details Defined in Data.Monoid.RightAction.Coproduct Methods actRight :: s -> (m :+: n) -> s Source #

inL :: m -> m :+: n Source #

Construct a coproduct value from the left constituent monoid.

Semantically, this is a monoid homomorphism: inL m1 <> inL m2 acts the same as inL (m1 <> m2).

inR :: n -> m :+: n Source #

Construct a coproduct value from the right constituent monoid.

Semantically, this is a monoid homomorphism: inR m1 <> inR m2 acts the same as inR (m1 <> m2).

normaliseCoproduct :: (Semigroup m, Semigroup n) => (m :+: n) -> [Either m n] Source #

Brings a coproduct into a canonical form, which is an alternating list of Lefts and Rights.

(The list may start with a Left or a Right, or be empty.)