Merge pull request #4340 from kubukoz/add-function-applyn

Add FunctionN.liftN, parLiftN

core/src/main/scala/cats/syntax/apply.scala

@@ -22,7 +22,7 @@
 package cats
 package syntax
 
-trait ApplySyntax extends TupleSemigroupalSyntax {
+trait ApplySyntax extends TupleSemigroupalSyntax with FunctionApplySyntax {
   @deprecated("Kept for binary compatibility", "2.10.0")
   final def catsSyntaxApply[F[_], A](fa: F[A], F: Apply[F]): Apply.Ops[F, A] =
     new Apply.Ops[F, A] {
@@ -51,7 +51,7 @@ final class ApplyFABOps[F[_], A, B](private val fab: F[A => B]) extends AnyVal {
 
   /**
    * @see [[Apply.ap]].
-   * 
+   *
    * Example:
    * {{{
    * scala> import cats.syntax.all._
@@ -86,7 +86,7 @@ final class ApplyFABCOps[F[_], A, B, C](private val ff: F[(A, B) => C]) extends
 
   /**
    * @see [[Apply.ap2]].
-   * 
+   *
    * Example:
    * {{{
    * scala> import cats.syntax.all._
@@ -109,7 +109,7 @@ final class ApplyFABCOps[F[_], A, B, C](private val ff: F[(A, B) => C]) extends
    * scala> noneF.ap2(noneInt, noneInt)
    * res3: Option[Long] = None
    * }}}
-   * 
+   *
    */
   def ap2(fa: F[A], fb: F[B])(implicit F: Apply[F]): F[C] = F.ap2(ff)(fa, fb)
 }
@@ -138,7 +138,7 @@ final class ApplyOps[F[_], A](private val fa: F[A]) extends AnyVal {
 
   /**
    * @see [[Apply.productR]].
-   * 
+   *
    * Example:
    * {{{
    * scala> import cats.syntax.all._
@@ -163,13 +163,13 @@ final class ApplyOps[F[_], A](private val fa: F[A]) extends AnyVal {
    *
    * scala> invalidInt.productR(invalidBool)
    * res3: ErrOr[Boolean] = Invalid(Invalid int.Invalid boolean.)
-   * }}}    
+   * }}}
    */
   def productR[B](fb: F[B])(implicit F: Apply[F]): F[B] = F.productR(fa)(fb)
 
   /**
    * @see [[Apply.productL]].
-   * 
+   *
    * Example:
    * {{{
    * scala> import cats.syntax.all._
@@ -194,7 +194,7 @@ final class ApplyOps[F[_], A](private val fa: F[A]) extends AnyVal {
    *
    * scala> invalidInt.productL(invalidBool)
    * res3: ErrOr[Int] = Invalid(Invalid int.Invalid boolean.)
-   * }}}    
+   * }}}
    */
   def productL[B](fb: F[B])(implicit F: Apply[F]): F[A] = F.productL(fa)(fb)
 
@@ -210,7 +210,7 @@ final class ApplyOps[F[_], A](private val fa: F[A]) extends AnyVal {
 
   /**
    * @see [[Apply.map2]].
-   * 
+   *
    * Example:
    * {{{
    * scala> import cats.syntax.all._
@@ -231,25 +231,25 @@ final class ApplyOps[F[_], A](private val fa: F[A]) extends AnyVal {
    *
    * scala> noneInt.map2(someLong)((i, l) => i.toString + l.toString)
    * res0: Option[String] = None
-   * }}} 
+   * }}}
    */
   def map2[B, C](fb: F[B])(f: (A, B) => C)(implicit F: Apply[F]): F[C] =
     F.map2(fa, fb)(f)
 
   /**
    * @see [[Apply.map2Eval]].
-   * 
+   *
    * Example:
    * {{{
    * scala> import cats.{Eval, Later}
    * scala> import cats.syntax.all._
-   * 
+   *
    * scala> val bomb: Eval[Option[Int]] = Later(sys.error("boom"))
    * scala> val x: Option[Int] = None
-   * 
+   *
    * scala> x.map2Eval(bomb)(_ + _).value
    * res0: Option[Int] = None
-   * }}} 
+   * }}}
    */
   def map2Eval[B, C](fb: Eval[F[B]])(f: (A, B) => C)(implicit F: Apply[F]): Eval[F[C]] =
     F.map2Eval(fa, fb)(f)

project/Boilerplate.scala

@@ -32,6 +32,7 @@ object Boilerplate {
     GenParallelArityFunctions,
     GenParallelArityFunctions2,
     GenFoldableArityFunctions,
+    GenFunctionSyntax,
     GenTupleParallelSyntax,
     GenTupleShowInstances,
     GenTupleMonadInstances,
@@ -594,7 +595,7 @@ object Boilerplate {
       | * @groupname FoldableSlidingN foldable arity
       | * @groupdesc FoldableSlidingN
       | *   Group sequential elements into fixed sized tuples by passing a "sliding window" over them.
-      | * 
+      | *
       | *   A foldable with fewer elements than the window size will return an empty list unlike `Iterable#sliding(size: Int)`.
       | *   Example:
       | *   {{{
@@ -604,12 +605,12 @@ object Boilerplate {
       | *
       | *   scala> Foldable[List].sliding4((1 to 10).toList)
       | *   val res1: List[(Int, Int, Int, Int)] = List((1,2,3,4), (2,3,4,5), (3,4,5,6), (4,5,6,7), (5,6,7,8), (6,7,8,9), (7,8,9,10))
-      | *   
+      | *
       | *   scala> Foldable[List].sliding4((1 to 2).toList)
       | *   val res2: List[(Int, Int, Int, Int)] = List()
       | *
       | *   }}}
-      | *   
+      | *
       | * @groupprio FoldableSlidingN 999
       | *
       | */
@@ -621,4 +622,41 @@ object Boilerplate {
       """
     }
   }
+
+  object GenFunctionSyntax extends Template {
+    def filename(root: File) = root / "cats" / "syntax" / "FunctionApplySyntax.scala"
+
+    override def range = 2 to maxArity
+
+    def content(tv: TemplateVals) = {
+      import tv._
+
+      val function = s"Function$arity[${`A..N`}, T]"
+
+      val typedParams = synVals.zip(synTypes).map { case (v, t) => s"$v: F[$t]" }.mkString(", ")
+
+      block"""
+      |package cats
+      |package syntax
+      |
+      |import cats.Functor
+      |import cats.Semigroupal
+      |
+      |trait FunctionApplySyntax {
+      |  implicit def catsSyntaxFunction1Apply[T, A0](f: Function1[A0, T]): Function1ApplyOps[T, A0] = new Function1ApplyOps(f)
+         -  implicit def catsSyntaxFunction${arity}Apply[T, ${`A..N`}](f: $function): Function${arity}ApplyOps[T, ${`A..N`}] = new Function${arity}ApplyOps(f)
+      |}
+      |
+      |private[syntax] final class Function1ApplyOps[T, A0](private val f: Function1[A0, T]) extends AnyVal with Serializable {
+      |  def liftN[F[_]: Functor](a0: F[A0]): F[T] = Functor[F].map(a0)(f)
+      |  def parLiftN[F[_]: Functor](a0: F[A0]): F[T] = Functor[F].map(a0)(f)
+      |}
+      |
+         -private[syntax] final class Function${arity}ApplyOps[T, ${`A..N`}](private val f: $function) extends AnyVal with Serializable {
+          - def liftN[F[_]: Functor: Semigroupal]($typedParams): F[T] = Semigroupal.map$arity(${`a..n`})(f)
+          - def parLiftN[F[_]: Parallel]($typedParams): F[T] = Parallel.parMap$arity(${`a..n`})(f)
+         -}
+      """
+    }
+  }
 }

tests/shared/src/test/scala/cats/tests/SyntaxSuite.scala

@@ -286,6 +286,54 @@ object SyntaxSuite {
     tfa.parFlatMap(mfone)
   }
 
+  def testLiftN[F[_]: Apply, A, B, C, T] = {
+    val fa = mock[F[A]]
+    val fb = mock[F[B]]
+    val fc = mock[F[C]]
+
+    val fapply1 = mock[A => T]
+
+    val result1 = fapply1.liftN(fa)
+
+    result1: F[T]
+
+    val fapply2 = mock[(A, B) => T]
+
+    val result2 = fapply2.liftN(fa, fb)
+
+    result2: F[T]
+
+    val fapply3 = mock[(A, B, C) => T]
+
+    val result3 = fapply3.liftN(fa, fb, fc)
+
+    result3: F[T]
+  }
+
+  def testParLiftN[F[_]: Parallel: Functor, A, B, C, T] = {
+    val fa = mock[F[A]]
+    val fb = mock[F[B]]
+    val fc = mock[F[C]]
+
+    val fapply1 = mock[A => T]
+
+    val result1 = fapply1.parLiftN(fa)
+
+    result1: F[T]
+
+    val fapply2 = mock[(A, B) => T]
+
+    val result2 = fapply2.parLiftN(fa, fb)
+
+    result2: F[T]
+
+    val fapply3 = mock[(A, B, C) => T]
+
+    val result3 = fapply3.parLiftN(fa, fb, fc)
+
+    result3: F[T]
+  }
+
   def testParallelBi[M[_], F[_], T[_, _]: Bitraverse, A, B, C, D](implicit P: Parallel.Aux[M, F]): Unit = {
     val tab = mock[T[A, B]]
     val f = mock[A => M[C]]