diff -r aa1fe1103ab8 -r b87784e19a77 src/Pure/General/symbol_explode.ML
--- a/src/Pure/General/symbol_explode.ML	Thu Sep 22 00:12:17 2016 +0200
+++ b/src/Pure/General/symbol_explode.ML	Thu Sep 22 11:25:27 2016 +0200
@@ -1,19 +1,12 @@
-(*  Title:      Pure/General/symbol.ML
+(*  Title:      Pure/General/symbol_explode.ML
     Author:     Makarius
 
-String explode operation for Isabelle symbols.
+String explode operation for Isabelle symbols (see also symbol.ML).
 *)
 
-signature SYMBOL_EXPLODE =
-sig
-  val symbol_explode: string -> string list
-end;
-
-structure Symbol_Explode: SYMBOL_EXPLODE =
+structure Symbol: sig val explode: string -> string list end =
 struct
 
-local
-
 fun is_ascii_letter c = #"A" <= c andalso c <= #"Z" orelse #"a" <= c andalso c <= #"z";
 fun is_ascii_letdig c =
   is_ascii_letter c orelse #"0" <= c andalso c <= #"9" orelse c = #"_" orelse c = #"'";
@@ -22,9 +15,7 @@
 fun is_utf8_trailer c = #"\128" <= c andalso c < #"\192";
 fun is_utf8_control c = #"\128" <= c andalso c < #"\160";
 
-in
-
-fun symbol_explode string =
+fun explode string =
   let
     fun char i = String.sub (string, i);
     fun string_range i j = String.substring (string, i, j - i);
@@ -36,29 +27,27 @@
     fun maybe_char c = maybe (fn c' => c = c');
     fun maybe_ascii_id i = if test is_ascii_letter i then many is_ascii_letdig (i + 1) else i;
 
-    fun explode i =
+    fun scan i =
       if i < n then
         let val ch = char i in
           (*encoded newline*)
-          if ch = #"\^M" then "\n" :: explode (maybe_char #"\n" (i + 1))
+          if ch = #"\^M" then "\n" :: scan (maybe_char #"\n" (i + 1))
           (*pseudo utf8: encoded ascii control*)
           else if ch = #"\192" andalso
             test is_utf8_control (i + 1) andalso not (test is_utf8 (i + 2))
-          then chr (Char.ord (char (i + 1)) - 128) :: explode (i + 2)
+          then chr (Char.ord (char (i + 1)) - 128) :: scan (i + 2)
           (*utf8*)
           else if is_utf8 ch then
             let val j = many is_utf8_trailer (i + 1)
-            in string_range i j :: explode j end
+            in string_range i j :: scan j end
           (*named symbol*)
           else if ch = #"\\" andalso test (fn c => c = #"<") (i + 1) then
             let val j = (i + 2) |> maybe_char #"^" |> maybe_ascii_id |> maybe_char #">"
-            in string_range i j :: explode j end
+            in string_range i j :: scan j end
           (*single character*)
-          else String.str ch :: explode (i + 1)
+          else String.str ch :: scan (i + 1)
         end
       else [];
-  in explode 0 end;
+  in scan 0 end;
 
 end;
-
-end;