Appease Scala 2.10 macro gods

typelevel · Sep 3, 2016 · f9dfea0 · f9dfea0
1 parent 6bdc2ae
commit f9dfea0
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Showing 3 changed files with 28 additions and 14 deletions.
diff --git a/core/src/main/scala/cats/arrow/FunctionK.scala b/core/src/main/scala/cats/arrow/FunctionK.scala
@@ -3,7 +3,7 @@ package arrow
 
 import cats.data.Coproduct
 
-import reflect.macros.blackbox.Context
+import cats.macros.MacroCompat
 
 trait FunctionK[F[_], G[_]] extends Serializable { self =>
   def apply[A](fa: F[A]): G[A]
@@ -37,13 +37,12 @@ object FunctionK {
 
 }
 
-object FunctionKMacros {
+object FunctionKMacros extends MacroCompat {
 
-  def lift[
-    F[_]: λ[α[_] ⇒ c.WeakTypeTag[α[_]]],
-    G[_]: λ[α[_] ⇒ c.WeakTypeTag[α[_]]]
-  ](c: Context)(
-    f: c.Expr[F[α] ⇒ G[α]] forSome { type α }
+  def lift[F[_], G[_]](c: Context)(
+    f: c.Expr[(F[α] ⇒ G[α]) forSome { type α }]
+  )(
+    implicit evF: c.WeakTypeTag[F[_]], evG: c.WeakTypeTag[G[_]]
   ): c.Expr[FunctionK[F, G]] = {
     import c.universe._
 
@@ -54,7 +53,7 @@ object FunctionKMacros {
 
     def punchHole(tpe: Type): Tree = tpe match {
       case PolyType(undet :: Nil, underlying: TypeRef) ⇒
-        val α = TypeName("α")
+        val α = compatNewTypeName(c, "α")
         def rebind(typeRef: TypeRef): Tree =
           if (typeRef.sym == undet) tq"$α"
           else {
@@ -82,8 +81,8 @@ object FunctionKMacros {
             s"type parameter $param must not be supplied when lifting function $trans to FunctionK")
           }
 
-        val F = punchHole(weakTypeTag[F[_]].tpe)
-        val G = punchHole(weakTypeTag[G[_]].tpe)
+        val F = punchHole(evF.tpe)
+        val G = punchHole(evG.tpe)
 
         q"""
           new FunctionK[$F, $G] {

diff --git a/macros/src/main/scala/cats/macros/compat.scala b/macros/src/main/scala/cats/macros/compat.scala
@@ -0,0 +1,15 @@
+package cats
+package macros
+
+/** Macro compatibility.
+  *
+  * Used only to push deprecation errors in core off into
+  * the macros project, as warnings.
+  */
+private[cats] class MacroCompat {
+
+  type Context = reflect.macros.Context
+  def compatNewTypeName(c: Context, name: String): c.TypeName =
+    c.universe.newTypeName(name)
+
+}
diff --git a/tests/src/test/scala/cats/tests/FunctionKTests.scala b/tests/src/test/scala/cats/tests/FunctionKTests.scala
@@ -69,24 +69,24 @@ class FunctionKTests extends CatsSuite {
 
   test("lift simple unary") {
     def optionToList[A](option: Option[A]): List[A] = option.toList
-    val fOptionToList = FunctionK.lift(optionToList)
+    val fOptionToList = FunctionK.lift(optionToList _)
     forAll { (a: Option[Int]) =>
       fOptionToList(a) should === (optionToList(a))
     }
 
-    val fO2I: FunctionK[Option, Iterable] = FunctionK.lift(Option.option2Iterable)
+    val fO2I: FunctionK[Option, Iterable] = FunctionK.lift(Option.option2Iterable _)
     forAll { (a: Option[String]) =>
       fO2I(a).toList should === (Option.option2Iterable(a).toList)
     }
 
-    val fNelFromListUnsafe = FunctionK.lift(NonEmptyList.fromListUnsafe)
+    val fNelFromListUnsafe = FunctionK.lift(NonEmptyList.fromListUnsafe _)
     forAll { (a: NonEmptyList[Int]) =>
       fNelFromListUnsafe(a.toList) should === (NonEmptyList.fromListUnsafe(a.toList))
     }
   }
 
   test("lift compound unary") {
-    val fNelFromList = FunctionK.lift[List, λ[α ⇒ Option[NonEmptyList[α]]]](NonEmptyList.fromList)
+    val fNelFromList = FunctionK.lift[List, λ[α ⇒ Option[NonEmptyList[α]]]](NonEmptyList.fromList _)
     forAll { (a: List[String]) =>
       fNelFromList(a) should === (NonEmptyList.fromList(a))
     }