Trait/Object

scala.collection.generic

IsSeqLike

Related Docs: object IsSeqLike | package generic

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trait IsSeqLike[Repr] extends AnyRef

Type class witnessing that a collection representation type Repr has elements of type A and has a conversion to SeqLike[A, Repr].

This type enables simple enrichment of Seqs with extension methods which can make full use of the mechanics of the Scala collections framework in their implementation.

Example usage:

class FilterMapImpl[A, Repr](val r: SeqLike[A, Repr]) {
  final def filterMap[B, That](f: A => Option[B])(implicit cbf: CanBuildFrom[Repr, B, That]): That =
    r.flatMap(f(_))
}
implicit def filterMap[Repr, A](r: Repr)(implicit fr: IsSeqLike[Repr]): FilterMapImpl[fr.A,Repr] =
  new FilterMapImpl(fr.conversion(r))

val l = List(1, 2, 3, 4, 5)
List(1, 2, 3, 4, 5) filterMap (i => if(i % 2 == 0) Some(i) else None)
// == List(2, 4)
Source
IsSeqLike.scala
See also

scala.collection.generic.IsTraversableLike

scala.collection.Seq

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Type Members

  1. abstract type A

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    The type of elements we can traverse over.

Abstract Value Members

  1. abstract val conversion: (Repr) ⇒ SeqLike[A, Repr]

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    A conversion from the representation type Repr to a SeqLike[A,Repr].