2 % (c) The AQUA Project, Glasgow University, 1996-1998
4 \section[TcTyDecls]{Typecheck type declarations}
7 module TcTyDecls ( tcTyDecl, 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(..) )
17 import TcMonoType ( tcHsTyVars, tcHsTheta, tcHsType,
18 kcHsContext, kcHsSigType, kcHsLiftedSigType
20 import TcEnv ( tcExtendTyVarEnv,
21 tcLookupTyCon, tcLookupRecId,
22 TyThingDetails(..), RecTcEnv
24 import TcType ( tcEqType, tyVarsOfTypes, tyVarsOfPred, ThetaType )
27 import DataCon ( DataCon, mkDataCon, dataConFieldLabels )
28 import FieldLabel ( fieldLabelName, fieldLabelType, allFieldLabelTags, mkFieldLabel )
29 import MkId ( mkDataConId, mkDataConWrapId, mkRecordSelId )
31 import Name ( Name, NamedThing(..) )
33 import TyCon ( TyCon, DataConDetails(..), visibleDataCons,
34 tyConName, tyConTheta,
35 tyConTyVars, isSynTyCon )
36 import VarSet ( intersectVarSet, isEmptyVarSet )
37 import PrelNames ( unpackCStringName, unpackCStringUtf8Name )
41 %************************************************************************
43 \subsection{Type checking}
45 %************************************************************************
48 tcTyDecl :: RecTcEnv -> RenamedTyClDecl -> TcM (Name, TyThingDetails)
49 tcTyDecl unf_env (TySynonym {tcdName = tycon_name, tcdSynRhs = rhs})
50 = tcLookupTyCon tycon_name `thenNF_Tc` \ tycon ->
51 tcExtendTyVarEnv (tyConTyVars tycon) $
52 tcHsType rhs `thenTc` \ rhs_ty ->
53 returnTc (tycon_name, SynTyDetails rhs_ty)
55 tcTyDecl unf_env (TyData {tcdND = new_or_data, tcdCtxt = context,
56 tcdName = tycon_name, tcdCons = con_decls})
57 = tcLookupTyCon tycon_name `thenNF_Tc` \ tycon ->
59 tyvars = tyConTyVars tycon
61 tcExtendTyVarEnv tyvars $
62 tcHsTheta context `thenTc` \ ctxt ->
63 tcConDecls new_or_data tycon tyvars ctxt con_decls `thenTc` \ data_cons ->
65 sel_ids = mkRecordSelectors unf_env tycon data_cons
67 returnTc (tycon_name, DataTyDetails ctxt data_cons sel_ids)
69 tcTyDecl unf_env (ForeignType {tcdName = tycon_name})
70 = returnTc (tycon_name, ForeignTyDetails)
73 mkRecordSelectors unf_env tycon data_cons
74 = -- We'll check later that fields with the same name
75 -- from different constructors have the same type.
76 [ mkRecordSelId tycon field unpack_id unpackUtf8_id
77 | field <- nubBy eq_name fields ]
79 fields = [ field | con <- visibleDataCons data_cons,
80 field <- dataConFieldLabels con ]
81 eq_name field1 field2 = fieldLabelName field1 == fieldLabelName field2
83 unpack_id = tcLookupRecId unf_env unpackCStringName
84 unpackUtf8_id = tcLookupRecId unf_env unpackCStringUtf8Name
88 %************************************************************************
90 \subsection{Kind and type check constructors}
92 %************************************************************************
95 kcConDetails :: NewOrData -> RenamedContext -> ConDetails Name -> TcM ()
96 kcConDetails new_or_data ex_ctxt details
97 = kcHsContext ex_ctxt `thenTc_`
98 mapTc_ kc_sig_type (conDetailsTys details)
100 kc_sig_type = case new_or_data of
101 DataType -> kcHsSigType
102 NewType -> kcHsLiftedSigType
103 -- Can't allow an unlifted type here, because we're effectively
104 -- going to remove the constructor while coercing it to a lifted type.
107 tcConDecls :: NewOrData -> TyCon -> [TyVar] -> ThetaType
108 -> DataConDetails RenamedConDecl -> TcM (DataConDetails DataCon)
110 tcConDecls new_or_data tycon tyvars ctxt con_decls
112 Unknown -> returnTc Unknown
113 HasCons n -> returnTc (HasCons n)
114 DataCons cs -> mapTc tc_con_decl cs `thenTc` \ data_cons ->
115 returnTc (DataCons data_cons)
117 tc_con_decl (ConDecl name wkr_name ex_tvs ex_ctxt details src_loc)
118 = tcAddSrcLoc src_loc $
119 tcHsTyVars ex_tvs (kcConDetails new_or_data ex_ctxt details) $ \ ex_tyvars ->
120 tcHsTheta ex_ctxt `thenTc` \ ex_theta ->
122 VanillaCon btys -> tc_datacon ex_tyvars ex_theta btys
123 InfixCon bty1 bty2 -> tc_datacon ex_tyvars ex_theta [bty1,bty2]
124 RecCon fields -> tc_rec_con ex_tyvars ex_theta fields
127 tc_datacon ex_tyvars ex_theta btys
128 = mapTc tcHsType (map getBangType btys) `thenTc` \ arg_tys ->
129 mk_data_con ex_tyvars ex_theta (map getBangStrictness btys) arg_tys []
131 tc_rec_con ex_tyvars ex_theta fields
132 = checkTc (null ex_tyvars) (exRecConErr name) `thenTc_`
133 mapTc tc_field (fields `zip` allFieldLabelTags) `thenTc` \ field_labels_s ->
135 field_labels = concat field_labels_s
136 arg_stricts = [str | (ns, bty) <- fields,
137 let str = getBangStrictness bty,
138 n <- ns -- One for each. E.g x,y,z :: !Int
141 mk_data_con ex_tyvars ex_theta arg_stricts
142 (map fieldLabelType field_labels) field_labels
144 tc_field ((field_label_names, bty), tag)
145 = tcHsType (getBangType bty) `thenTc` \ field_ty ->
146 returnTc [mkFieldLabel (getName name) tycon field_ty tag | name <- field_label_names]
148 mk_data_con ex_tyvars ex_theta arg_stricts arg_tys fields
150 data_con = mkDataCon name arg_stricts fields
151 tyvars (thinContext arg_tys ctxt)
154 tycon data_con_id data_con_wrap_id
156 data_con_id = mkDataConId wkr_name data_con
157 data_con_wrap_id = mkDataConWrapId data_con
161 -- The context for a data constructor should be limited to
162 -- the type variables mentioned in the arg_tys
163 thinContext arg_tys ctxt
164 = filter in_arg_tys ctxt
166 arg_tyvars = tyVarsOfTypes arg_tys
167 in_arg_tys pred = not $ isEmptyVarSet $
168 tyVarsOfPred pred `intersectVarSet` arg_tyvars
172 %************************************************************************
174 \subsection{Errors and contexts}
176 %************************************************************************
181 = ptext SLIT("Can't combine named fields with locally-quantified type variables")
183 (ptext SLIT("In the declaration of data constructor") <+> ppr name)