mkSpecOcc = mk_simple_deriv varName "$s"
mkForeignExportOcc = mk_simple_deriv varName "$f"
mkNewTyCoOcc = mk_simple_deriv tcName ":Co"
-mkInstTyCoOcc = mk_simple_deriv tcName ":Co" -- derived from rep ty
+mkInstTyCoOcc = mk_simple_deriv tcName ":CoF" -- derived from rep ty
mkEqPredCoOcc = mk_simple_deriv tcName "$co"
-- Generic derivable classes