Scala example source code file (TraverseSyntax.scala)

This example Scala source code file (TraverseSyntax.scala) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Scala by Example" ^TM.

Learn more about this Scala project at its project page.

Java - Scala tags/keywords

applicative, option, state, totraverseops

The TraverseSyntax.scala Scala example source code

package scalaz
package syntax

/** Wraps a value `self` and provides methods related to `Traverse` */
final class TraverseOps[F[_],A] private[syntax](val self: F[A])(implicit val F: Traverse[F]) extends Ops[F[A]] {
  ////

  import Leibniz.===

  final def tmap[B](f: A => B) =
    F.map(self)(f)

  final def traverse[G[_], B](f: A => G[B])(implicit G: Applicative[G]): G[F[B]] =
    G.traverse(self)(f)

  /** A version of `traverse` that infers the type constructor `G` */
  final def traverseU[GB](f: A => GB)(implicit G: Unapply[Applicative, GB]): G.M[F[G.A]] /*G[F[B]]*/ =
    F.traverseU[A, GB](self)(f)(G)

  /** A version of `traverse` where a subsequent monadic join is applied to the inner result. */
  final def traverseM[G[_], B](f: A => G[F[B]])(implicit G: Applicative[G], FM: Bind[F]): G[F[B]] =
    F.traverseM[A, G, B](self)(f)(G, FM)

  /** Traverse with the identity function */
  final def sequence[G[_], B](implicit ev: A === G[B], G: Applicative[G]): G[F[B]] = {
    val fgb: F[G[B]] = ev.subst[F](self)
    F.sequence(fgb)
  }

  /** A version of `sequence` that infers the nested type constructor */
  final def sequenceU(implicit G: Unapply[Applicative, A]): G.M[F[G.A]] /*G[F[A]] */ = {
    G.TC.traverse(self)(x => G.apply(x))
  }

  /** A version of `traverse` specialized for `State` */
  final def traverseS[S, B](f: A => State[S, B]): State[S, F[B]] =
    F.traverseS[S, A, B](self)(f)

  /**
   * A version of `traverse` specialized for `State[S, G[B]]` that internally uses a `Trampoline`
   * to avoid stack-overflow.
   */
  final def traverseSTrampoline[G[_]: Applicative, S, B](f: A => State[S, G[B]]): State[S, G[F[B]]] =
    F.traverseSTrampoline[S, G, A, B](self)(f)

  /**
   * A version of `traverse` specialized for `Kleisli[G, S, B]` that internally uses a `Trampoline`
   * to avoid stack-overflow.
   */
  final def traverseKTrampoline[G[_]: Applicative, S, B](f: A => Kleisli[G, S, B]): Kleisli[G, S, F[B]] =
    F.traverseKTrampoline[S, G, A, B](self)(f)

  final def runTraverseS[S, B](s: S)(f: A => State[S, B]): (S, F[B]) =
    F.runTraverseS(self, s)(f)

  final def reverse: F[A] = F.reverse(self)

  final def zipWith[B, C](fb: F[B])(f: (A, Option[B]) => C): (List[B], F[C]) = F.zipWith(self, fb)(f)
  final def zipWithL[B, C](fb: F[B])(f: (A, Option[B]) => C): F[C] = F.zipWithL(self, fb)(f)
  final def zipWithR[B, C](fb: F[B])(f: (Option[A], B) => C): F[C] = F.zipWithR(self, fb)(f)
  final def indexed: F[(Int, A)] = F.indexed(self)
  final def zipL[B](fb: F[B]): F[(A, Option[B])] = F.zipL(self, fb)
  final def zipR[B](fb: F[B]): F[(Option[A], B)] = F.zipR(self, fb)
  final def mapAccumL[S,B](z: S)(f: (S,A) => (S,B)): (S, F[B]) =
    F.mapAccumL(self, z)(f)
  final def mapAccumR[S,B](z: S)(f: (S,A) => (S,B)): (S, F[B]) =
    F.mapAccumR(self, z)(f)
  ////
}

sealed trait ToTraverseOps0 {
  implicit def ToTraverseOpsUnapply[FA](v: FA)(implicit F0: Unapply[Traverse, FA]) =
    new TraverseOps[F0.M,F0.A](F0(v))(F0.TC)

}

trait ToTraverseOps extends ToTraverseOps0 with ToFunctorOps with ToFoldableOps {
  implicit def ToTraverseOps[F[_],A](v: F[A])(implicit F0: Traverse[F]) =
    new TraverseOps[F,A](v)

  ////

  ////
}

trait TraverseSyntax[F[_]] extends FunctorSyntax[F] with FoldableSyntax[F] {
  implicit def ToTraverseOps[A](v: F[A]): TraverseOps[F, A] = new TraverseOps[F,A](v)(TraverseSyntax.this.F)

  def F: Traverse[F]
  ////

  ////
}