--- a/progs/dfa.scala	Thu Jul 25 14:39:37 2019 +0100
+++ b/progs/dfa.scala	Sun Jul 28 01:00:41 2019 +0100
@@ -1,13 +1,13 @@
 // DFAs in Scala  using partial functions
 import scala.util.Try
 
-// type abbreviation for partial functions
+// a type abbreviation for partial functions
 type :=>[A, B] = PartialFunction[A, B]
 
 
-case class DFA[A, C](start: A,               // starting state
-                     delta: (A, C) :=> A,    // transition (partial fun)
-                     fins:  A => Boolean) {  // final states
+case class DFA[A, C](start: A,               // the starting state
+                     delta: (A, C) :=> A,    // transitions (partial fun)
+                     fins:  A => Boolean) {  // the final states
 
   def deltas(q: A, s: List[C]) : A = s match {
     case Nil => q
@@ -52,7 +52,7 @@
 case object S2 extends S
 case object Sink extends S
 
-// transition function with a sink state
+// a transition function with a sink state
 val sigma : (S, Char) :=> S = 
   { case (S0, 'a') => S1
     case (S1, 'a') => S2