src/Pure/Syntax/simple_syntax.ML

 
 in
 
 fun read scan s =
   (case
-      Symbol.explode s |>
+      SymbolPos.explode (s, Position.none) |>
       Lexicon.tokenize lexicon false |>
       Scan.read stopper scan of
     SOME x => x
   | NONE => error ("Malformed input: " ^ quote s));