src/Pure/Isar/ROOT.ML

 use "proof_data.ML";
 use "proof_history.ML";
 use "args.ML";
 use "attrib.ML";
 use "method.ML";
+use "calculation.ML";
 
 (*outer syntax*)
 use "comment.ML";
 use "outer_lex.ML";
 use "outer_parse.ML";