Finish being able to parse the first example file.

hsrc/Syntax/Lexer.x

@@ -21,7 +21,7 @@ $bindigit = [01]
 $typestart   = [A-Z\_]
 $valstart    = [a-z\_]
 $identrest   = [a-zA-Z0-9\_\.]
-$opident     = [\~\!\@\#\$\%\^\&\*\+\-\=\.\:\<\>\?\_]
+$opident     = [\~\!\@\#\$\%\^\&\*\+\-\=\.\<\>\?\_]
 $escape_char = [abfnrtv'\"\\]
 
 :-
@@ -42,6 +42,7 @@ $escape_char = [abfnrtv'\"\\]
   $typestart $identrest*                           { emitS TokTypeIdent }
   $valstart $identrest*                            { emitS TokValIdent  }
   $opident+                                        { emitS TokOpIdent   }
+  ":"+                                             { emitS TokOpIdent   }
 
 -- Characters and Strings
   ['].[']                                          { emitS TokChar }