Test for a new collection class hierarchy respecting mutability

Author: odersky

tests/pos-custom-args/captures/mut-collections.scala

@@ -0,0 +1,51 @@
+package colltestMut
+import caps.*
+import collection.*, mutable.*, immutable.*
+
+object collection:
+  trait Iterable[A]:
+    this: Iterable[A]^ =>
+    type C[X] <: Iterable[X]^
+    def map[B](f: A => B): C[B]^{f} = ???
+
+  trait View[A] extends Iterable[A]:
+    this: View[A]^ =>
+    type C[X] = View[X]^{this}
+
+  trait Seq[A] extends Iterable[A]:
+    this: Seq[A]^ =>
+    override def map[B](f: A => B): C[B] = ???
+
+object immutable:
+  import collection.*
+  trait Seq[A] extends Iterable[A], Pure:
+    type C[X] <: Seq[X]
+
+  class List[A] extends Seq[A]:
+    type C[X] = List[X]
+
+
+object mutable:
+  import collection.*
+  trait Seq[A] extends collection.Seq[A]:
+    this: Seq[A]^ =>
+    type C[X] <: Seq[X]^
+
+  trait Buffer[A] extends Seq[A], Mutable:
+    this: Buffer[A]^ =>
+    type C[X] = Buffer[X]^
+
+class IO extends SharedCapability
+class Ref extends Mutable
+
+object Test:
+  def test(io: IO, ref: Ref, f: Int => Int) =
+    val xs1: List[Int] = ???
+    val ys1 = xs1.map(f)
+    val xs2: Buffer[Int]^ = ???
+    val ys2 = xs2.map(f)
+    val xs3: Buffer[Int]^ = ???
+    val zs3 = freeze(xs3)
+    val xs4: Buffer[Int]^ = ???
+    val vs4: View[Int]^{xs4} = ???
+    val ys4 = vs4.map(f)