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functor.scala
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functor.scala
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/*
* Copyright (c) 2015 Typelevel
*
* Permission is hereby granted, free of charge, to any person obtaining a copy of
* this software and associated documentation files (the "Software"), to deal in
* the Software without restriction, including without limitation the rights to
* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
* the Software, and to permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
package cats
package syntax
trait FunctorSyntax extends Functor.ToFunctorOps {
implicit final def catsSyntaxFunctorTuple2Ops[F[_], A, B](fab: F[(A, B)]): FunctorTuple2Ops[F, A, B] =
new FunctorTuple2Ops[F, A, B](fab)
implicit final def catsSyntaxIfF[F[_]](fa: F[Boolean]): IfFOps[F] =
new IfFOps[F](fa)
}
final class FunctorTuple2Ops[F[_], A, B](private val fab: F[(A, B)]) extends AnyVal {
/**
* Lifts `Tuple2#_1` to Functor
*
* {{{
* scala> import cats.data.Chain
* scala> import cats.syntax.functor._
*
* scala> Chain((1, 2), (3, 4), (5, 6))._1F == Chain(1, 3, 5)
* res0: Boolean = true
* }}}
*/
def _1F(implicit F: Functor[F]): F[A] = F.map(fab)(_._1)
/**
* Lifts `Tuple2#_2` to Functor
*
* {{{
* scala> import cats.data.Chain
* scala> import cats.syntax.functor._
*
* scala> Chain((1, 2), (3, 4), (5, 6))._2F == Chain(2, 4, 6)
* res0: Boolean = true
* }}}
*/
def _2F(implicit F: Functor[F]): F[B] = F.map(fab)(_._2)
/**
* Lifts `Tuple2#swap` to Functor
*
* {{{
* scala> import cats.data.Chain
* scala> import cats.syntax.functor._
*
* scala> Chain((1, 2), (3, 4), (5, 6)).swapF == Chain((2, 1), (4, 3), (6, 5))
* res0: Boolean = true
* }}}
*/
def swapF(implicit F: Functor[F]): F[(B, A)] = F.map(fab)(_.swap)
/**
* Un-zips an `F[(A, B)]` consisting of element pairs or Tuple2 into two separate F's tupled.
*
* NOTE: Check for effect duplication, possibly memoize before
*
* {{{
* scala> import cats.data.Chain
* scala> import cats.syntax.functor._
*
* scala> Chain((1, 2), (3, 4), (5, 6)).unzip == ((Chain(1, 3, 5), Chain(2, 4, 6)))
* res0: Boolean = true
* }}}
*/
def unzip(implicit F: Functor[F]): (F[A], F[B]) = F.unzip(fab)
}
final class IfFOps[F[_]](private val fa: F[Boolean]) extends AnyVal {
/**
* Lifts `if` to Functor
*
* Example:
* {{{
* scala> import cats.syntax.all._
*
* scala> List(true, false, false).ifF(1, 0)
* res0: List[Int] = List(1, 0, 0)
* }}}
*/
def ifF[B](ifTrue: => B, ifFalse: => B)(implicit F: Functor[F]): F[B] = F.ifF(fa)(ifTrue, ifFalse)
}