diff -r 0eaa1851a5b6 -r db0ff630bbb7 exps/bit.scala
--- a/exps/bit.scala	Sat Mar 16 11:15:22 2019 +0000
+++ b/exps/bit.scala	Thu Apr 11 17:37:00 2019 +0100
@@ -392,10 +392,10 @@
 def erase(r: ARexp) : Rexp = r match{
   case AZERO => ZERO
   case AONE(_) => ONE
-  case APRED(bs, f, s) => PRED(f, s)
-  case AALTS(bs, rs) => ALTS(rs.map(erase(_)))
-  case ASEQ(bs, r1, r2) => SEQ (erase(r1), erase(r2))
-  case ASTAR(cs, r)=> STAR(erase(r))
+  case APRED(_, f, s) => PRED(f, s)
+  case AALTS(_, rs) => ALTS(rs.map(erase(_)))
+  case ASEQ(_, r1, r2) => SEQ(erase(r1), erase(r2))
+  case ASTAR(_, r)=> STAR(erase(r))
 }
 
 
@@ -442,9 +442,9 @@
 
 def flats(rs: List[ARexp]): List[ARexp] = rs match {
     case Nil => Nil
-    case AZERO :: rs1 => flats(rs1)
-    case AALTS(bs, rs1) :: rs2 => rs1.map(fuse(bs, _)) ::: flats(rs2)
-    case r1 :: rs2 => r1 :: flats(rs2)
+    case AZERO::rs1 => flats(rs1)
+    case AALTS(bs, rs1)::rs2 => rs1.map(fuse(bs, _)) ::: flats(rs2)
+    case r1::rs2 => r1::flats(rs2)
 }
 
 def stack(r1: ARexp, r2: ARexp) = r1 match {
@@ -738,6 +738,17 @@
 println(strings(pders_simp(qs.toList, q)))
 
 
+val w : Rexp = ((("a" | "b") | "b".%) | "ab") ~ ("a".% | ("b" | "b"))
+val ws = "ab"
+
+lexing(w, ws)
+blexing_simp(w, ws)
+
+
+        
+
+
+
 
 System.exit(0)