Merge pull request #2045 from dotty-staging/fix-hlist-hmap

Fix type inference for HLists and HMaps

1 files changed, 23 insertions, 0 deletions

diff --git a/tests/pos/t5070.scala b/tests/pos/t5070.scala
index 410afba14..0e5c0ffc0 100644
--- a/tests/pos/t5070.scala
+++ b/tests/pos/t5070.scala
@@ -13,3 +13,26 @@ class Test {
 
   implicitly[a.T](b(a)) // works
 }
+
+
+class ImplicitVsTypeAliasTezt {
+
+    class Monad[m[_]] {
+        type For[a] = _For[m, a]
+        implicit def toFor[a](m: m[a]): For[a] = throw new Error("todo") // lookup fails
+//        implicit def toFor[a](m: m[a]): _For[m, a] = throw new Error("todo") // fine.
+    }
+
+    trait _For[m[_], a] {
+        def map[b](p: a => b): m[b]
+    }
+
+    def useMonad[m[_], a](m: m[a])(implicit i: Monad[m]) = {
+        import i._
+
+        // value map is not a member of type parameter m[a]
+        for {
+            x <- m
+        } yield x.toString
+    }
+}