diff options
Diffstat (limited to 'tests/untried/pos/depmet_implicit_chaining_zw.scala')
-rw-r--r-- | tests/untried/pos/depmet_implicit_chaining_zw.scala | 28 |
1 files changed, 28 insertions, 0 deletions
diff --git a/tests/untried/pos/depmet_implicit_chaining_zw.scala b/tests/untried/pos/depmet_implicit_chaining_zw.scala new file mode 100644 index 000000000..ce5ea476d --- /dev/null +++ b/tests/untried/pos/depmet_implicit_chaining_zw.scala @@ -0,0 +1,28 @@ +trait Zero +trait Succ[N] + +trait ZipWith[N, S] { + type T + val x: T = sys.error("") +} + +object ZipWith { + implicit def ZeroZipWith[S] = new ZipWith[Zero, S] { + type T = Stream[S] + } + + implicit def SuccZipWith[N, S, R](implicit zWith : ZipWith[N, R]) = 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 _2 = Succ[Succ[Zero]] + val zw = ?[ZipWith[_2, Int => String => Boolean]].x // : Stream[Int] => Stream[String] => Stream[Boolean] + // val zw = implicitly[ZipWith[Succ[Succ[Zero]], Int => String => Boolean]{type T = Stream[Int] => Stream[String] => Stream[Boolean]}].x +} |