diff options
Diffstat (limited to 'tests/pos/depmet_implicit_norm_ret.scala')
-rw-r--r-- | tests/pos/depmet_implicit_norm_ret.scala | 34 |
1 files changed, 34 insertions, 0 deletions
diff --git a/tests/pos/depmet_implicit_norm_ret.scala b/tests/pos/depmet_implicit_norm_ret.scala new file mode 100644 index 000000000..42bfb9fe1 --- /dev/null +++ b/tests/pos/depmet_implicit_norm_ret.scala @@ -0,0 +1,34 @@ +object Test{ + def ?[S <: AnyRef](implicit w : S) : w.type = w + + // fallback, lower priority (overloading rules apply: pick alternative in subclass lowest in subtyping lattice) + class ZipWithDefault { + implicit def ZeroZipWith[S]: Test.ZipWith[S]{type T = Stream[S]} = new ZipWith[S] { + type T = Stream[S] + } + } + + object ZipWith extends ZipWithDefault { + // def apply[S: ZipWith](s : S) = ?[ZipWith[S]].zipWith(s) // TODO: bug return type should be inferred + def apply[S](s : S)(implicit zw: ZipWith[S]): zw.T = zw.zipWith(s) + + implicit def SuccZipWith[S,R](implicit zWith : ZipWith[R]): Test.ZipWith[S => R]{type T = Stream[S] => zWith.T} = new ZipWith[S => R] { + type T = Stream[S] => zWith.T // dependent types replace the associated types functionality + } + } + + import ZipWith._ + + trait ZipWith[S] { + type T + def zipWith : S => T = sys.error("") + } + + // bug: inferred return type = (Stream[A]) => java.lang.Object with Test.ZipWith[B]{type T = Stream[B]}#T + // this seems incompatible with vvvvvvvvvvvvvvvvvvvvvv -- #3731 + def map1[A,B](f : A => B) = ZipWith(f)(SuccZipWith) // this typechecks but fails in -Ycheck:first + val tst1: Stream[Int] = map1[String, Int]{x: String => x.length}.apply(Stream("a")) + + def map2[A,B](f : A => B) = ZipWith(f) // this finds ZeroZipWith where scalac finds SuccZipWith and fails typechecking in the next line. + val tst2: Stream[Int] = map2{x: String => x.length}.apply(Stream("a")) +} |