+
+dataConTheta :: DataCon -> ClassContext
+dataConTheta dc = dcTheta dc
+
+-- And the same deal for the original arg tys:
+
+dataConInstOrigArgTys :: DataCon -> [Type] -> [Type]
+dataConInstOrigArgTys (MkData {dcOrigArgTys = arg_tys, dcTyVars = tyvars,
+ dcExTyVars = ex_tyvars}) inst_tys
+ = map (substTy (mkTyVarSubst (tyvars ++ ex_tyvars) inst_tys)) arg_tys