part 2 of the dependent method refactoring: imp...

part 2 of the dependent method refactoring: improved interaction with
implicit search (needed for oopsla paper)

more to come in this area, see e.g. #3346 (stanford edsl stuff)

reopens #13, which wasn't fixed properly before imo, anyway (have a look at -Xprint:typer output before this commit: a type that's not expressible in surface syntax is inferred -- also removed duplicate test file)

closes #3731: co-evolve type alias type symbols when their rhs is
updated and they are referenced by type selections (see typemap)

review by odersky

1 files changed, 63 insertions, 0 deletions

diff --git a/test/files/pos/depmet_implicit_oopsla_session.scala b/test/files/pos/depmet_implicit_oopsla_session.scala
new file mode 100644
index 0000000000..21588a56ad
--- /dev/null
+++ b/test/files/pos/depmet_implicit_oopsla_session.scala
@@ -0,0 +1,63 @@
+object Sessions {
+  trait Session[This] {
+    type Dual
+    type HasDual[D] = Session[This]{type Dual=D}
+    def run(p: This, dp: Dual): Unit
+  }
+
+  implicit object StopSession extends Session[Stop] {
+    type Dual = Stop
+
+    def run(p: Stop, dp: Stop): Unit = {}
+  }
+
+  implicit def InDual[A, B](implicit sessionDIn: Session[B]) =
+    new Session[In[A, B]] {
+      type Dual = Out[A, sessionDIn.Dual]
+
+      def run(p: In[A, B], dp: Dual): Unit =
+        sessionDIn.run(p.func(dp.x), dp.y)
+  }
+
+  implicit def OutDual[A, B](implicit sessionDOut: Session[B]) =
+    new Session[Out[A, B]] {
+     type Dual = In[A, sessionDOut.Dual]
+
+     def run(p: Out[A, B], dp: Dual): Unit =
+       sessionDOut.run(p.y, dp.func(p.x))
+  }
+
+  sealed case class Stop()
+  sealed case class In[-A, +B](func: A => B)
+  sealed case class Out[+A, +B](x: A, y: B)
+
+  def addServer =
+    In{x: Int =>
+    In{y: Int => System.out.println("Thinking")
+    Out(x+y,
+    Stop())}}
+
+  def addClient =
+    Out(3,
+    Out(4, { System.out.println("Waiting")
+    In{z: Int => System.out.println(z)
+    Stop()}}))
+
+  def runSession[S, D: Session[S]#HasDual](p: S, dp: D) =
+    implicitly[Session[S]#HasDual[D]].run(p, dp)
+
+  // def runSession[S, D](p: S, dp: D)(implicit s: Session[S]#HasDual[D]) =
+  //   s.run(p, dp)
+  //
+  // def runSession[S, D](p: S, dp: D)(implicit s: Session[S]{type Dual=D}) =
+  //   s.run(p, dp)
+
+  // TODO: can we relax the ordering restrictions on dependencies so that we can use
+  // def runSession[S](p: S, dp: s.Dual)(implicit s: Session[S]) =
+  //   s.run(p, dp)
+  // to emphasise similarity of type parameters and implicit arguments:
+  // def runSession[S][val s: Session[S]](p: S, dp: s.Dual) =
+  //   s.run(p, dp)
+
+  def myRun = runSession(addServer, addClient)
+}
\ No newline at end of file