cats.kernel

Monoid

trait Monoid[A] extends Semigroup[A]

A monoid is a semigroup with an identity. 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 = "".

Linear Supertypes
Semigroup[A], Serializable, Serializable, Any
Known Subclasses
BigDecimalGroup, BigIntGroup, BitSetSemilattice, BoundedSemilattice, ByteGroup, CommutativeGroup, CommutativeMonoid, DoubleGroup, DurationGroup, FloatGroup, Function0Group, Function0Monoid, Function1Group, Function1Monoid, Group, IntGroup, ListMonoid, LongGroup, MapMonoid, OptionMonoid, QueueMonoid, SetSemilattice, ShortGroup, StreamMonoid, StringMonoid, UnitAlgebra, VectorMonoid
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Inherited
  1. Monoid
  2. Semigroup
  3. Serializable
  4. Serializable
  5. Any
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Visibility
  1. Public
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Abstract Value Members

  1. abstract def combine(x: A, y: A): A

    Associative operation which combines two values.

    Associative operation which combines two values.

    Definition Classes
    Semigroup

  2. abstract def empty: A

    Return the identity element for this monoid.

  3. abstract def getClass(): Class[_]

    Definition Classes
    Any

Concrete Value Members

  1. final def !=(arg0: Any): Boolean

    Definition Classes
    Any

  2. final def ##(): Int

    Definition Classes
    Any

  3. final def ==(arg0: Any): Boolean

    Definition Classes
    Any

  4. final def asInstanceOf[T0]: T0

    Definition Classes
    Any

  5. def combineAll(as: TraversableOnce[A]): A

    Given a sequence of as, sum them using the monoid and return the total.

  6. def combineAllOption(as: TraversableOnce[A]): Option[A]

    Given a sequence of as, combine them and return the total.

    Given a sequence of as, combine them and return the total.

    If the sequence is empty, returns None. Otherwise, returns Some(total).

    Definition Classes
    Monoid → Semigroup

  7. def combineN(a: A, n: Int): A

    Return a appended to itself n times.

    Return a appended to itself n times.

    Definition Classes
    Monoid → Semigroup

  8. def equals(arg0: Any): Boolean

    Definition Classes
    Any

  9. def hashCode(): Int

    Definition Classes
    Any

  10. def isEmpty(a: A)(implicit ev: Eq[A]): Boolean

    Tests if a is the identity.

  11. final def isInstanceOf[T0]: Boolean

    Definition Classes
    Any

  12. def repeatedCombineN(a: A, n: Int): A

    Return a combined with itself more than once.

    Return a combined with itself more than once.

    Attributes
    protected[this]
    Definition Classes
    Semigroup

  13. def toString(): String

    Definition Classes
    Any

Inherited from Semigroup[A]

Inherited from Serializable

Inherited from Serializable

Inherited from Any

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