; gbl_tvs' <- tcGetGlobalTyVars
; constrained_dicts' <- mappM zonkInst constrained_dicts
- ; let constrained_tvs' = tyVarsOfInsts constrained_dicts'
- qtvs = (tau_tvs' `minusVarSet` oclose (fdPredsOfInsts constrained_dicts) gbl_tvs')
- `minusVarSet` constrained_tvs'
+ ; let qtvs1 = tau_tvs' `minusVarSet` oclose (fdPredsOfInsts constrained_dicts) gbl_tvs'
+ -- As in tcSimplifyInfer
+
+ -- Do not quantify over constrained type variables:
+ -- this is the monomorphism restriction
+ constrained_tvs' = tyVarsOfInsts constrained_dicts'
+ qtvs = qtvs1 `minusVarSet` constrained_tvs'
+ pp_bndrs = pprWithCommas (quotes . ppr) bndrs
+
+ -- Warn in the mono
+ ; warn_mono <- doptM Opt_WarnMonomorphism
+ ; warnTc (warn_mono && (constrained_tvs' `intersectsVarSet` qtvs1))
+ (vcat[ ptext SLIT("the Monomorphism Restriction applies to the binding")
+ <> plural bndrs <+> ptext SLIT("for") <+> pp_bndrs,
+ ptext SLIT("Consider giving a type signature for") <+> pp_bndrs])
+
; traceTc (text "tcSimplifyRestricted" <+> vcat [
pprInsts wanteds, pprInsts constrained_dicts',
ppr _binds,
getDefaultTys :: Bool -> Bool -> TcM [Type]
getDefaultTys extended_deflts ovl_strings
= do { mb_defaults <- getDeclaredDefaultTys
- ; case mb_defaults of
- Just tys -> return tys -- User-supplied defaults
+ ; case mb_defaults of {
+ Just tys -> return tys ; -- User-supplied defaults
Nothing -> do
-- No use-supplied default
++
[integer_ty,doubleTy]
++
- opt_deflt ovl_strings string_ty) }}
+ opt_deflt ovl_strings string_ty) } } }
where
opt_deflt True ty = [ty]
opt_deflt False ty = []