diff -r 75d9f9e5906f -r 05cfce0fdef7 progs/comb1.scala
--- a/progs/comb1.scala	Thu Nov 07 00:07:16 2019 +0000
+++ b/progs/comb1.scala	Thu Nov 14 01:21:02 2019 +0000
@@ -60,18 +60,18 @@
 implicit def char2parser(c: Char) = CharParser(c)
 
 implicit def ParserOps[I, T](p: Parser[I, T])(implicit ev: I => Seq[_]) = new {
-  def || (q : => Parser[I, T]) = new AltParser[I, T](p, q)
+  def ||(q : => Parser[I, T]) = new AltParser[I, T](p, q)
   def ==>[S] (f: => T => S) = new FunParser[I, T, S](p, f)
   def ~[S] (q : => Parser[I, S]) = new SeqParser[I, T, S](p, q)
 }
 
 implicit def StringOps(s: String) = new {
-  def || (q : => Parser[String, String]) = new AltParser[String, String](s, q)
-  def || (r: String) = new AltParser[String, String](s, r)
+  def ||(q : => Parser[String, String]) = new AltParser[String, String](s, q)
+  def ||(r: String) = new AltParser[String, String](s, r)
   def ==>[S] (f: => String => S) = new FunParser[String, String, S](s, f)
-  def ~[S] (q : => Parser[String, S]) = 
+  def ~[S](q : => Parser[String, S]) = 
     new SeqParser[String, String, S](s, q)
-  def ~ (r: String) = 
+  def ~(r: String) = 
     new SeqParser[String, String, String](s, r)
 }
 
@@ -131,15 +131,6 @@
 lazy val F: Parser[String, Int] = 
   ("(" ~ E ~ ")") ==> { case ((x, y), z) => y } || NumParserInt
 
-/* same parser but producing a string
-lazy val E: Parser[String, String] = 
-  (T ~ "+" ~ E) ==> { case ((x, y), z) => "(" + x + ")+(" + z + ")"} || T 
-lazy val T: Parser[String, String] = 
-  (F ~ "*" ~ T) ==> { case ((x, y), z) => "(" + x + ")*("+ z + ")"} || F
-lazy val F: Parser[String, String] = 
-  ("(" ~ E ~ ")") ==> { case ((x, y), z) => y } || NumParser
-*/
-
 println(E.parse_all("1+3+4"))
 println(E.parse("1+3+4"))
 println(E.parse_all("4*2+3"))
@@ -150,7 +141,14 @@
 println(E.parse_all("(1+2)+3"))
 println(E.parse_all("1+2+3"))  
 
-
+/* same parser but producing a string
+lazy val E: Parser[String, String] = 
+  (T ~ "+" ~ E) ==> { case ((x, y), z) => "(" + x + ")+(" + z + ")"} || T 
+lazy val T: Parser[String, String] = 
+  (F ~ "*" ~ T) ==> { case ((x, y), z) => "(" + x + ")*("+ z + ")"} || F
+lazy val F: Parser[String, String] = 
+  ("(" ~ E ~ ")") ==> { case ((x, y), z) => y } || NumParser
+*/
 
 // no left-recursion allowed, otherwise will loop
 lazy val EL: Parser[String, Int] = 
@@ -166,7 +164,7 @@
 
 // ambiguous
 lazy val S : Parser[String, String] =
-  ("1" ~ S ~ S) ==> { case ((x, y), z) => x + y + z } || ""
+  ("1" ~ S ~ S ~ S) ==> { case (((x, y), z), v) => x + y + z } || ""
 
 S.parse("1" * 10)
 
@@ -199,14 +197,14 @@
 One.parse("111")
 
 (One ~ One).parse("111")
-(One ~ One ~ One).parse("111")
+(One ~ One ~ One).parse("1111")
 (One ~ One ~ One ~ One).parse("1111")
 
 (One || Two).parse("111")
 
 
 // a problem with the arithmetic expression parser -> gets 
-// slow with deep nestedness
+// slow with deeply nested parentheses
 E.parse("1")
 E.parse("(1)")
 E.parse("((1))")
@@ -214,3 +212,15 @@
 E.parse("((((1))))")
 E.parse("((((((1))))))")
 E.parse("(((((((1)))))))")
+
+
+
+
+/*
+
+starting symbols
+tokenise/detokenise
+:paste
+pairs in sequences
+
+*/
\ No newline at end of file