Monoid<T> mixin

A monoid is a semigroup with an identity (empty).

A monoid is a specialization of a semigroup, so its operation must be associative.

Additionally, combine(x, empty) == combine(empty, x) == x.

For example, if we have Monoid<String>, with combine as string concatenation, then empty = "":

final instance = Monoid.instance<String>('', (a1, a2) => '$a1$a2');

expect(instance.combine('abc', instance.empty), instance.combine(instance.empty, 'abc'));
expect(instance.combine('abc', instance.empty), 'abc');

Superclass Constraints

• Semigroup<T>

Properties

empty → T

Return the identity element for this monoid.

no setter

hashCode → int

The hash code for this object.

no setter, inherited

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

Methods

combine(T x, T y) → T

Associative operation which combines two values.

inherited

combineN(T a, int n) → T

Return a appended to itself n times.

override

intercalate(T middle) → Semigroup<T>

Return a Semigroup which inserts middle between each pair of elements.

inherited

isEmpty(T a, Eq<T> eq) → bool

Tests if a is the identity (empty).

noSuchMethod(Invocation invocation) → dynamic

Invoked when a nonexistent method or property is accessed.

inherited

reverse() → Monoid<T>

Return a Monoid that reverses the order.

override

toString() → String

A string representation of this object.

inherited

Operators

operator ==(Object other) → bool

The equality operator.

inherited

Static Methods

instance<A>(A emptyValue, A f(A a1, A a2)) → Monoid<A>

Create a Monoid instance from the given function and empty value.

override