fix shape_of_string

Author: hhugo

compiler/lib/shape.ml

@@ -98,17 +98,22 @@ let of_string (s : string) =
     | 'F' ->
         next ();
         parse_fun ()
-    | c -> failwith (String.make 1 c)
+    | _ -> assert false
   and parse_block acc =
-    let x = parse_shape () in
     match current () with
-    | ',' ->
-        next ();
-        parse_block (x :: acc)
     | ']' ->
         next ();
-        Block (List.rev (x :: acc))
-    | _ -> assert false
+        Block (List.rev acc)
+    | _ -> (
+        let x = parse_shape () in
+        match current () with
+        | ',' ->
+            next ();
+            parse_block (x :: acc)
+        | ']' ->
+            next ();
+            Block (List.rev (x :: acc))
+        | _ -> assert false)
   and parse_fun () =
     let () = parse_char '(' in
     let arity = parse_int 0 in