monocle.std.Set.scala Maven / Gradle / Ivy

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package monocle.std

import monocle.function.{At, Empty}
import monocle.{Lens, Prism}

object set extends SetOptics

trait SetOptics {

  implicit def emptySet[A]: Empty[Set[A]] = new Empty[Set[A]] {
    def empty = Prism[Set[A], Unit](s => if(s.isEmpty) Some(()) else None)(_ => Set.empty[A])
  }

  implicit def atSet[A]: At[Set[A], A, Boolean] = new At[Set[A], A, Boolean] {
    def at(a: A) = Lens[Set[A], Boolean](_.contains(a))(b => set => if(b) set + a else set - a)
  }

}