add dfa for longIDs (which are used for accessing things from structures/modules)

compiler/scanner.sml

@@ -4,8 +4,13 @@ struct
 
   val intDfa = Dfa.fromString "[0-9]+"
   val wordDfa = Dfa.fromString "0w[0-9]+"
-  val realDfa = "[0-9]+.[0-9]+"
+  val realDfa = Dfa.fromString "[0-9]+.[0-9]+"
+
   val idDfa = Dfa.fromString "[a-zA-Z][a-zA-Z0-9_']*"
+  val longIdDfa =
+    Dfa.fromString "[a-zA-Z[(a-zA-Z0-9_']*(\\.[a-zA-Z][a-zA-Z0-9_']*)+"
+
+      Hello.world
 
   fun skipFormattingChars (str, pos) =
     if pos = String.size str then