scala> case class Foo[A](a: A)
// defined case class Foo
scala> Foo(1)
val res0: Foo[Int] = Foo(1)
scala> val x: Foo[String] = res0
-- [E007] Type Mismatch Error: -------------------------------------------------
1 |val x: Foo[String] = res0
  |                     ^^^^
  |                     Found:    (res0 : Foo[Int])
  |                     Required: Foo[String]
  |
  | longer explanation available when compiling with `-explain`
1 error found
