2 % (c) The AQUA Project, Glasgow University, 1996-1998
4 \section[TcTyDecls]{Typecheck type declarations}
7 module TcTyDecls ( tcTyDecl1, kcConDetails ) where
9 #include "HsVersions.h"
11 import HsSyn ( TyClDecl(..), ConDecl(..), ConDetails(..),
12 getBangType, getBangStrictness, conDetailsTys
14 import RnHsSyn ( RenamedTyClDecl, RenamedConDecl, RenamedContext )
15 import BasicTypes ( NewOrData(..), RecFlag, isRec )
17 import TcMonoType ( tcHsRecType, tcHsTyVars, tcRecTheta,
18 kcHsContext, kcHsSigType, kcHsLiftedSigType
20 import TcEnv ( tcExtendTyVarEnv,
21 tcLookupTyCon, tcLookupRecId,
22 TyThingDetails(..), RecTcEnv
24 import TcType ( tcSplitTyConApp_maybe, tcEqType,
25 tyVarsOfTypes, tyVarsOfPred,
26 mkTyConApp, mkTyVarTys, mkForAllTys,
31 import DataCon ( DataCon, mkDataCon, dataConFieldLabels, dataConRepType,
32 isNullaryDataCon, dataConOrigArgTys )
33 import MkId ( mkDataConId, mkDataConWrapId, mkRecordSelId )
36 import Name ( Name, NamedThing(..) )
38 import TyCon ( TyCon, AlgTyConFlavour(..), tyConTyVars )
39 import VarSet ( intersectVarSet, isEmptyVarSet )
40 import PrelNames ( unpackCStringName, unpackCStringUtf8Name )
41 import ListSetOps ( equivClasses )
44 %************************************************************************
46 \subsection{Type checking}
48 %************************************************************************
51 tcTyDecl1 :: RecFlag -> RecTcEnv -> RenamedTyClDecl -> TcM (Name, TyThingDetails)
52 tcTyDecl1 is_rec unf_env (TySynonym {tcdName = tycon_name, tcdSynRhs = rhs})
53 = tcLookupTyCon tycon_name `thenNF_Tc` \ tycon ->
54 tcExtendTyVarEnv (tyConTyVars tycon) $
55 tcHsRecType is_rec rhs `thenTc` \ rhs_ty ->
56 -- Note tcHsRecType not tcHsRecSigType; we allow type synonyms
57 -- that aren't types; e.g. type List = []
59 -- If the RHS mentions tyvars that aren't in scope, we'll
60 -- quantify over them:
62 -- will become type T = forall a. a->a
64 -- With gla-exts that's right, but for H98 we should complain.
65 -- We can now do that here without falling into
66 -- a black hole, we still do it in rnDecl (TySynonym case)
68 returnTc (tycon_name, SynTyDetails rhs_ty)
70 tcTyDecl1 is_rec unf_env (TyData {tcdND = new_or_data, tcdCtxt = context,
71 tcdName = tycon_name, tcdCons = con_decls})
72 = tcLookupTyCon tycon_name `thenNF_Tc` \ tycon ->
74 tyvars = tyConTyVars tycon
76 tcExtendTyVarEnv tyvars $
78 -- Typecheck the pieces
79 tcRecTheta is_rec context `thenTc` \ ctxt ->
80 mapTc (tcConDecl is_rec new_or_data tycon tyvars ctxt) con_decls `thenTc` \ data_cons ->
81 tcRecordSelectors is_rec unf_env tycon data_cons `thenTc` \ sel_ids ->
82 returnTc (tycon_name, DataTyDetails ctxt data_cons sel_ids)
84 tcTyDecl1 is_rec unf_env (ForeignType {tcdName = tycon_name})
85 = returnTc (tycon_name, ForeignTyDetails)
89 %************************************************************************
91 \subsection{Kind and type check constructors}
93 %************************************************************************
96 kcConDetails :: NewOrData -> RenamedContext -> ConDetails Name -> TcM ()
97 kcConDetails new_or_data ex_ctxt details
98 = kcHsContext ex_ctxt `thenTc_`
99 mapTc_ kc_sig_type (conDetailsTys details)
101 kc_sig_type = case new_or_data of
102 DataType -> kcHsSigType
103 NewType -> kcHsLiftedSigType
104 -- Can't allow an unlifted type here, because we're effectively
105 -- going to remove the constructor while coercing it to a lifted type.
108 tcConDecl :: RecFlag -> NewOrData -> TyCon -> [TyVar] -> ThetaType -> RenamedConDecl -> TcM DataCon
110 tcConDecl is_rec new_or_data tycon tyvars ctxt (ConDecl name wkr_name ex_tvs ex_ctxt details src_loc)
111 = tcAddSrcLoc src_loc $
112 tcHsTyVars ex_tvs (kcConDetails new_or_data ex_ctxt details) $ \ ex_tyvars ->
113 tcRecTheta is_rec ex_ctxt `thenTc` \ ex_theta ->
115 VanillaCon btys -> tc_datacon ex_tyvars ex_theta btys
116 InfixCon bty1 bty2 -> tc_datacon ex_tyvars ex_theta [bty1,bty2]
117 RecCon fields -> tc_rec_con ex_tyvars ex_theta fields
119 tc_datacon ex_tyvars ex_theta btys
121 arg_stricts = map getBangStrictness btys
122 tys = map getBangType btys
124 mapTc (tcHsRecType is_rec) tys `thenTc` \ arg_tys ->
125 mk_data_con ex_tyvars ex_theta arg_stricts arg_tys []
127 tc_rec_con ex_tyvars ex_theta fields
128 = checkTc (null ex_tyvars) (exRecConErr name) `thenTc_`
129 mapTc tc_field (fields `zip` allFieldLabelTags) `thenTc` \ field_labels_s ->
131 field_labels = concat field_labels_s
132 arg_stricts = [str | (ns, bty) <- fields,
133 let str = getBangStrictness bty,
134 n <- ns -- One for each. E.g x,y,z :: !Int
137 mk_data_con ex_tyvars ex_theta arg_stricts
138 (map fieldLabelType field_labels) field_labels
140 tc_field ((field_label_names, bty), tag)
141 = tcHsRecType is_rec (getBangType bty) `thenTc` \ field_ty ->
142 returnTc [mkFieldLabel (getName name) tycon field_ty tag | name <- field_label_names]
144 mk_data_con ex_tyvars ex_theta arg_stricts arg_tys fields
146 data_con = mkDataCon name arg_stricts fields
147 tyvars (thinContext arg_tys ctxt)
150 tycon data_con_id data_con_wrap_id
152 data_con_id = mkDataConId wkr_name data_con
153 data_con_wrap_id = mkDataConWrapId data_con
157 -- The context for a data constructor should be limited to
158 -- the type variables mentioned in the arg_tys
159 thinContext arg_tys ctxt
160 = filter in_arg_tys ctxt
162 arg_tyvars = tyVarsOfTypes arg_tys
163 in_arg_tys pred = not $ isEmptyVarSet $
164 tyVarsOfPred pred `intersectVarSet` arg_tyvars
168 %************************************************************************
170 \subsection{Record selectors}
172 %************************************************************************
175 tcRecordSelectors is_rec unf_env tycon data_cons
176 -- Omit the check that the fields have consistent types if
177 -- the group is recursive; TcTyClsDecls.tcGroup will repeat
178 -- with NonRecursive once we have tied the knot
179 | isRec is_rec = returnTc sel_ids
180 | otherwise = mapTc check groups `thenTc_`
183 fields = [ field | con <- data_cons
184 , field <- dataConFieldLabels con ]
186 -- groups is list of fields that share a common name
187 groups = equivClasses cmp_name fields
188 cmp_name field1 field2 = fieldLabelName field1 `compare` fieldLabelName field2
190 sel_ids = [ mkRecordSelId tycon field unpack_id unpackUtf8_id
191 | (field : _) <- groups ]
193 check fields@(first_field_label : other_fields)
194 -- These fields all have the same name, but are from
195 -- different constructors in the data type
196 = -- Check that all the fields in the group have the same type
197 -- NB: this check assumes that all the constructors of a given
198 -- data type use the same type variables
199 checkTc (all (tcEqType field_ty) other_tys) (fieldTypeMisMatch field_name)
201 field_ty = fieldLabelType first_field_label
202 field_name = fieldLabelName first_field_label
203 other_tys = map fieldLabelType other_fields
205 unpack_id = tcLookupRecId unf_env unpackCStringName
206 unpackUtf8_id = tcLookupRecId unf_env unpackCStringUtf8Name
211 %************************************************************************
213 \subsection{Errors and contexts}
215 %************************************************************************
219 fieldTypeMisMatch field_name
220 = sep [ptext SLIT("Different constructors give different types for field"), quotes (ppr field_name)]
223 = ptext SLIT("Can't combine named fields with locally-quantified type variables")
225 (ptext SLIT("In the declaration of data constructor") <+> ppr name)