--- a/progs/app04.scala	Sun Oct 15 20:47:14 2017 +0100
+++ b/progs/app04.scala	Tue Oct 17 13:49:45 2017 +0100
@@ -1,7 +1,7 @@
 abstract class Val
 case object Empty extends Val
 case class Chr(c: Char) extends Val
-case class Seq(v1: Val, v2: Val) extends Val
+case class Sequ(v1: Val, v2: Val) extends Val
 case class Left(v: Val) extends Val
 case class Right(v: Val) extends Val
 case class Stars(vs: List[Val]) extends Val