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

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package monocle.std

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

import scalaz.{ISet, Order}

object iset extends ISetOptics

trait ISetOptics {

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

  implicit def atISet[A: Order]: At[ISet[A], A, Boolean] = new At[ISet[A], A, Boolean] {
    def at(a: A) = Lens[ISet[A], Boolean](_.member(a))(b => set => if(b) set insert a else set delete a)
  }

}