src/HOLCF/Tools/fixrec_package.ML

   val add_fixpat_cmd: Attrib.binding * string list -> theory -> theory
   val add_matchers: (string * string) list -> theory -> theory
   val setup: theory -> theory
 end;
 
-structure FixrecPackage: FIXREC_PACKAGE =
+structure FixrecPackage :> FIXREC_PACKAGE =
 struct
 
 val fix_eq2 = @{thm fix_eq2};
 val def_fix_ind = @{thm def_fix_ind};