Merge pull request #694 from dotty-staging/fix/dependent-methods

Fix/dependent methods

2 files changed, 47 insertions, 0 deletions

diff --git a/tests/pos/depmet_implicit_chaining_zw.scala b/tests/pos/depmet_implicit_chaining_zw.scala
new file mode 100644
index 000000000..f0e8a373b
--- /dev/null
+++ b/tests/pos/depmet_implicit_chaining_zw.scala
@@ -0,0 +1,32 @@
+trait Zero
+trait Succ[N]
+
+trait ZipWith[N, S] {
+  type T
+  val x: T = sys.error("")
+}
+
+object ZipWith {
+  implicit def ZeroZipWith[S]: ZipWith[Zero,S]{type T = Stream[S]} = new ZipWith[Zero, S] {
+    type T = Stream[S]
+  }
+
+  implicit def SuccZipWith[N, S, R](implicit zWith : ZipWith[N, R]): ZipWith[Succ[N],S => R]{type T = Stream[S] => zWith.T} = new ZipWith[Succ[N], S => R] {
+    type T = Stream[S] => zWith.T // dependent types replace the associated types functionality
+  }
+
+  // can't use implicitly[ZipWith[Succ[Succ[Zero]], Int => String => Boolean]],
+  // since that will chop of the {type T = ... } refinement in adapt (pt = ZipWith[Succ[Succ[Zero]], Int => String => Boolean])
+  // this works
+  // def zipWith(implicit zw: ZipWith[Succ[Succ[Zero]], Int => String => Boolean]): zw.T = zw.x
+  // thus, I present ?: implicitly on steroids!
+  def ?[T <: AnyRef](implicit w: T): w.type = w
+
+  type _0 = Zero
+  type _1 = Succ[Zero]
+  type _2 = Succ[Succ[Zero]]
+  val zw = ?[ZipWith[_2, Int => String => Boolean]](
+    SuccZipWith[_1, Int, String => Boolean](
+      SuccZipWith[_0, String, Boolean])).x
+  // val zw = implicitly[ZipWith[Succ[Succ[Zero]], Int => String => Boolean]{type T = Stream[Int] => Stream[String] => Stream[Boolean]}].x
+}
diff --git a/tests/pos/implicitNums.scala b/tests/pos/implicitNums.scala
new file mode 100644
index 000000000..48c5302f7
--- /dev/null
+++ b/tests/pos/implicitNums.scala
@@ -0,0 +1,15 @@
+object Test {
+
+  trait Number
+  trait Zero extends Number
+  trait Succ[N <: Number](n: N) extends Number
+
+  implicit def succ[N <: Number](implicit n: N): Succ[N] = new Succ[N](n) {}
+  implicit def zero: Zero = new Zero{}
+
+  implicitly[Zero]
+  implicitly[Succ[Zero]]
+  implicitly[Succ[Succ[Zero]]]
+  implicitly[Succ[Succ[Succ[Zero]]]]
+
+}