tcFamInstDecl1 :: TyClDecl Name -> TcM (Maybe TyThing) -- Nothing if error
-tcFamInstDecl1 (decl@TySynonym {})
+ -- "type instance"
+tcFamInstDecl1 (decl@TySynonym {tcdLName = L loc tc_name})
= kcIdxTyPats decl $ \k_tvs k_typats resKind family ->
do { -- check that the family declaration is for a synonym
unless (isSynTyCon family) $
; t_typats <- mappM tcHsKindedType k_typats
; t_rhs <- tcHsKindedType k_rhs
- -- !!!of the form: forall t_tvs. (tcdLName decl) t_typats = t_rhs
- ; return Nothing -- !!!TODO: need TyThing for indexed synonym
+ -- (3) construct representation tycon
+ ; rep_tc_name <- newFamInstTyConName tc_name loc
+ ; tycon <- buildSynTyCon rep_tc_name t_tvs (SynonymTyCon t_rhs)
+ (Just (family, t_typats))
+
+ ; return $ Just (ATyCon tycon)
}}
-
+
+ -- "newtype instance" and "data instance"
tcFamInstDecl1 (decl@TyData {tcdND = new_or_data, tcdLName = L loc tc_name,
tcdCons = cons})
= kcIdxTyPats decl $ \k_tvs k_typats resKind family ->
; t_typats <- mappM tcHsKindedType k_typats
; stupid_theta <- tcHsKindedContext k_ctxt
- ; rep_tc_name <- newFamInstTyConName tc_name (srcSpanStart loc)
+ -- (3) construct representation tycon
+ ; rep_tc_name <- newFamInstTyConName tc_name loc
; tycon <- fixM (\ tycon -> do
- { data_cons <- mappM (addLocM (tcConDecl unbox_strict new_or_data
- tycon t_tvs))
+ { data_cons <- mappM (addLocM (tcConDecl unbox_strict tycon t_tvs))
k_cons
; tc_rhs <-
case new_or_data of
; syn_tcs <- tcExtendGlobalEnv [syn_tc] (tcSynDecls decls)
; return (syn_tc : syn_tcs) }
+ -- "type"
tcSynDecl
(TySynonym {tcdLName = L _ tc_name, tcdTyVars = tvs, tcdSynRhs = rhs_ty})
= tcTyVarBndrs tvs $ \ tvs' -> do
{ traceTc (text "tcd1" <+> ppr tc_name)
; rhs_ty' <- tcHsKindedType rhs_ty
- ; return (ATyCon (buildSynTyCon tc_name tvs' (SynonymTyCon rhs_ty'))) }
+ ; tycon <- buildSynTyCon tc_name tvs' (SynonymTyCon rhs_ty') Nothing
+ ; return (ATyCon tycon)
+ }
--------------------
tcTyClDecl :: (Name -> RecFlag) -> TyClDecl Name -> TcM [TyThing]
-- Check that we don't use families without -findexed-types
; checkTc idx_tys $ badFamInstDecl tc_name
- ; return [ATyCon $ buildSynTyCon tc_name tvs' (OpenSynTyCon kind Nothing)]
+ ; tycon <- buildSynTyCon tc_name tvs' (OpenSynTyCon kind Nothing) Nothing
+ ; return [ATyCon tycon]
}
-- "newtype family" or "data family" declaration
; return [ATyCon tycon]
}
- -- "newtype", "data", "newtype instance", "data instance"
+ -- "newtype" and "data"
tcTyClDecl1 calc_isrec
(TyData {tcdND = new_or_data, tcdCtxt = ctxt, tcdTyVars = tvs,
tcdLName = L _ tc_name, tcdKindSig = mb_ksig, tcdCons = cons})
(newtypeConError tc_name (length cons))
; tycon <- fixM (\ tycon -> do
- { data_cons <- mappM (addLocM (tcConDecl unbox_strict new_or_data
- tycon final_tvs))
+ { data_cons <- mappM (addLocM (tcConDecl unbox_strict tycon final_tvs))
cons
; tc_rhs <-
if null cons && is_boot -- In a hs-boot file, empty cons means
-----------------------------------
tcConDecl :: Bool -- True <=> -funbox-strict_fields
- -> NewOrData
-> TyCon -> [TyVar]
-> ConDecl Name
-> TcM DataCon
-tcConDecl unbox_strict NewType tycon tc_tvs -- Newtypes
- (ConDecl name _ tvs ex_ctxt details res_ty _)
- = tcTyVarBndrs tvs $ \ tvs' -> do
- do { (univ_tvs, ex_tvs, eq_preds, data_tc) <- tcResultType tycon tc_tvs tvs' res_ty
-
- -- Check that a newtype has no existential stuff
- ; checkTc (null ex_tvs && null (unLoc ex_ctxt)) (newtypeExError name)
-
- ; let tc_datacon field_lbls arg_ty
- = do { arg_ty' <- tcHsKindedType arg_ty -- No bang on newtype
- ; buildDataCon (unLoc name) False {- Prefix -}
- [NotMarkedStrict]
- (map unLoc field_lbls)
- univ_tvs [] -- No existentials
- [] [] -- No equalities, predicates
- [arg_ty']
- data_tc }
-
- ; case details of
- PrefixCon [arg_ty] -> tc_datacon [] arg_ty
- RecCon [HsRecField field_lbl arg_ty _] -> tc_datacon [field_lbl] arg_ty
- other ->
- failWithTc (newtypeFieldErr name (length (hsConArgs details)))
- -- Check that the constructor has exactly one field
- }
-
-tcConDecl unbox_strict DataType tycon tc_tvs -- Data types
+tcConDecl unbox_strict tycon tc_tvs -- Data types
(ConDecl name _ tvs ctxt details res_ty _)
= tcTyVarBndrs tvs $ \ tvs' -> do
{ ctxt' <- tcHsKindedContext ctxt
-- NB: this check assumes that all the constructors of a given
-- data type use the same type variables
where
- tvs1 = mkVarSet (dataConAllTyVars con1)
- res1 = dataConResTys con1
+ (tvs1, _, _, res1) = dataConSig con1
+ ts1 = mkVarSet tvs1
fty1 = dataConFieldType con1 label
checkOne (_, con2) -- Do it bothways to ensure they are structurally identical
- = do { checkFieldCompat label con1 con2 tvs1 res1 res2 fty1 fty2
- ; checkFieldCompat label con2 con1 tvs2 res2 res1 fty2 fty1 }
+ = do { checkFieldCompat label con1 con2 ts1 res1 res2 fty1 fty2
+ ; checkFieldCompat label con2 con1 ts2 res2 res1 fty2 fty1 }
where
- tvs2 = mkVarSet (dataConAllTyVars con2)
- res2 = dataConResTys con2
+ (tvs2, _, _, res2) = dataConSig con2
+ ts2 = mkVarSet tvs2
fty2 = dataConFieldType con2 label
checkFieldCompat fld con1 con2 tvs1 res1 res2 fty1 fty2
= do { checkTc (isJust mb_subst1) (resultTypeMisMatch fld con1 con2)
; checkTc (isJust mb_subst2) (fieldTypeMisMatch fld con1 con2) }
where
- mb_subst1 = tcMatchTys tvs1 res1 res2
+ mb_subst1 = tcMatchTy tvs1 res1 res2
mb_subst2 = tcMatchTyX tvs1 (expectJust "checkFieldCompat" mb_subst1) fty1 fty2
-------------------------------
= setSrcSpan (srcLocSpan (getSrcLoc con)) $
addErrCtxt (dataConCtxt con) $
do { checkTc (dataConTyCon con == tc) (badDataConTyCon con)
- ; checkValidType ctxt (dataConUserType con) }
+ ; checkValidType ctxt (dataConUserType con)
+ ; ifM (isNewTyCon tc) (checkNewDataCon con)
+ }
where
ctxt = ConArgCtxt (dataConName con)
-------------------------------
+checkNewDataCon :: DataCon -> TcM ()
+-- Checks for the data constructor of a newtype
+checkNewDataCon con
+ = do { checkTc (isSingleton arg_tys) (newtypeFieldErr con (length arg_tys))
+ -- One argument
+ ; checkTc (null eq_spec) (newtypePredError con)
+ -- Return type is (T a b c)
+ ; checkTc (null ex_tvs && null theta) (newtypeExError con)
+ -- No existentials
+ }
+ where
+ (_univ_tvs, ex_tvs, eq_spec, theta, arg_tys, _res_ty) = dataConFullSig con
+
+-------------------------------
checkValidClass :: Class -> TcM ()
checkValidClass cls
= do { -- CHECK ARITY 1 FOR HASKELL 1.4
= sep [ptext SLIT("A newtype constructor cannot have an existential context,"),
nest 2 $ ptext SLIT("but") <+> quotes (ppr con) <+> ptext SLIT("does")]
+newtypePredError con
+ = sep [ptext SLIT("A newtype constructor must have a return type of form T a1 ... an"),
+ nest 2 $ ptext SLIT("but") <+> quotes (ppr con) <+> ptext SLIT("does not")]
+
newtypeFieldErr con_name n_flds
= sep [ptext SLIT("The constructor of a newtype must have exactly one field"),
nest 2 $ ptext SLIT("but") <+> quotes (ppr con_name) <+> ptext SLIT("has") <+> speakN n_flds]
kindOfFamily | isSynTyCon family = ptext SLIT("type synonym")
| isDataTyCon family = ptext SLIT("data type")
| isNewTyCon family = ptext SLIT("newtype")
+ | otherwise = pprPanic "wrongKindOfFamily" (ppr family)
emptyConDeclsErr tycon
= sep [quotes (ppr tycon) <+> ptext SLIT("has no constructors"),
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