trait Fold[S, A] extends Serializable

A Fold can be seen as a Getter with many targets or a weaker PTraversal which cannot modify its target.

Fold is on the top of the Optic hierarchy which means that Getter, PTraversal, POptional, PLens, PPrism and PIso are valid Fold

S

the source of a Fold

A

the target of a Fold

Self Type
Fold[S, A]
Source
Fold.scala
Linear Supertypes
Serializable, AnyRef, Any
Known Subclasses
Getter, PIso, PLens, POptional, PPrism, PTraversal
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Inherited
  1. Fold
  2. Serializable
  3. AnyRef
  4. Any
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Visibility
  1. Public
  2. Protected

Abstract Value Members

  1. abstract def foldMap[M](f: (A) => M)(s: S)(implicit arg0: Monoid[M]): M

    map each target to a Monoid and combine the results underlying representation of Fold, all Fold methods are defined in terms of foldMap

Concrete Value Members

  1. def all(p: (A) => Boolean): (S) => Boolean

    check if all targets satisfy the predicate

  2. def andThen[B](other: Fold[A, B]): Fold[S, B]

    compose a Fold with another Fold

  3. def exist(p: (A) => Boolean): (S) => Boolean

    check if at least one target satisfies the predicate

  4. def find(p: (A) => Boolean): (S) => Option[A]

    find the first target matching the predicate

  5. def fold(s: S)(implicit ev: Monoid[A]): A

    combine all targets using a target's Monoid

  6. def getAll(s: S): List[A]

    get all the targets of a Fold

  7. def headOption(s: S): Option[A]

    get the first target

  8. def index[I, A1](i: I)(implicit evIndex: Index[A, I, A1]): Fold[S, A1]
  9. def isEmpty(s: S): Boolean

    check if there is no target

  10. def lastOption(s: S): Option[A]

    get the last target

  11. def length(s: S): Int

    calculate the number of targets

  12. def nonEmpty(s: S): Boolean

    check if there is at least one target

  13. def some[A1](implicit ev1: =:=[A, Option[A1]]): Fold[S, A1]
  14. def to[C](f: (A) => C): Fold[S, C]

    Compose with a function lifted into a Getter

Deprecated Value Members

  1. def left[C]: Fold[Either[S, C], Either[A, C]]
    Annotations
    @deprecated
    Deprecated

    (Since version 3.0.0-M4) no replacement

  2. def right[C]: Fold[Either[C, S], Either[C, A]]
    Annotations
    @deprecated
    Deprecated

    (Since version 3.0.0-M4) no replacement