diff -r 4fbdc80076cb -r 412556272333 progs/comb1.scala
--- a/progs/comb1.scala	Thu Oct 24 14:39:29 2019 +0100
+++ b/progs/comb1.scala	Fri Oct 25 14:55:31 2019 +0100
@@ -5,7 +5,7 @@
  * constraint IsSeq, which means that the input type 'I' needs 
  * to be a sequence. */
 
- type IsSeq[A] = A => Seq[_]
+type IsSeq[A] = A => Seq[_]
 
 abstract class Parser[I : IsSeq, T] {
   def parse(ts: I): Set[(T, I)]
@@ -84,6 +84,7 @@
    ("b" ~ Pal ~ "b") ==> { case ((x, y), z) => x + y + z } || "a" || "b" || "")
 
 Pal.parse_all("abaaaba")
+Pal.parse_all("abacba")
 Pal.parse("abaaaba")
 
 println("Palindrome: " + Pal.parse_all("abaaaba"))
@@ -97,6 +98,13 @@
 P.parse_all(")(")
 P.parse_all("()")
 
+lazy val PC : Parser[String, Int] = 
+  ("(" ~ PC ~ ")" ~ PC ==> { case (((_, x), _), y) => x + y + 2 } || 
+   "" ==> { (s) => 0 })
+
+PC.parse_all("(((()()))())")
+P.parse_all("(((()()))()))")
+
 // Arithmetic Expressions (Terms and Factors)
 
 lazy val E: Parser[String, Int] =