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 ( 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,
35 import VarSet ( intersectVarSet, isEmptyVarSet )
36 import PrelNames ( unpackCStringName, unpackCStringUtf8Name )
40 %************************************************************************
42 \subsection{Type checking}
44 %************************************************************************
47 tcTyDecl :: RecTcEnv -> RenamedTyClDecl -> TcM (Name, TyThingDetails)
48 tcTyDecl unf_env (TySynonym {tcdName = tycon_name, tcdSynRhs = rhs})
49 = tcLookupTyCon tycon_name `thenNF_Tc` \ tycon ->
50 tcExtendTyVarEnv (tyConTyVars tycon) $
51 tcHsType rhs `thenTc` \ rhs_ty ->
52 returnTc (tycon_name, SynTyDetails rhs_ty)
54 tcTyDecl unf_env (TyData {tcdND = new_or_data, tcdCtxt = context,
55 tcdName = tycon_name, tcdCons = con_decls})
56 = tcLookupTyCon tycon_name `thenNF_Tc` \ tycon ->
58 tyvars = tyConTyVars tycon
60 tcExtendTyVarEnv tyvars $
61 tcHsTheta context `thenTc` \ ctxt ->
62 tcConDecls new_or_data tycon tyvars ctxt con_decls `thenTc` \ data_cons ->
64 sel_ids = mkRecordSelectors unf_env tycon data_cons
66 returnTc (tycon_name, DataTyDetails ctxt data_cons sel_ids)
68 tcTyDecl unf_env (ForeignType {tcdName = tycon_name})
69 = returnTc (tycon_name, ForeignTyDetails)
72 mkRecordSelectors unf_env tycon data_cons
73 = -- We'll check later that fields with the same name
74 -- from different constructors have the same type.
75 [ mkRecordSelId tycon field unpack_id unpackUtf8_id
76 | field <- nubBy eq_name fields ]
78 fields = [ field | con <- visibleDataCons data_cons,
79 field <- dataConFieldLabels con ]
80 eq_name field1 field2 = fieldLabelName field1 == fieldLabelName field2
82 unpack_id = tcLookupRecId unf_env unpackCStringName
83 unpackUtf8_id = tcLookupRecId unf_env unpackCStringUtf8Name
87 %************************************************************************
89 \subsection{Kind and type check constructors}
91 %************************************************************************
94 kcConDetails :: NewOrData -> RenamedContext -> ConDetails Name -> TcM ()
95 kcConDetails new_or_data ex_ctxt details
96 = kcHsContext ex_ctxt `thenTc_`
97 mapTc_ kc_sig_type (conDetailsTys details)
99 kc_sig_type = case new_or_data of
100 DataType -> kcHsSigType
101 NewType -> kcHsLiftedSigType
102 -- Can't allow an unlifted type here, because we're effectively
103 -- going to remove the constructor while coercing it to a lifted type.
106 tcConDecls :: NewOrData -> TyCon -> [TyVar] -> ThetaType
107 -> DataConDetails RenamedConDecl -> TcM (DataConDetails DataCon)
109 tcConDecls new_or_data tycon tyvars ctxt con_decls
111 Unknown -> returnTc Unknown
112 HasCons n -> returnTc (HasCons n)
113 DataCons cs -> mapTc tc_con_decl cs `thenTc` \ data_cons ->
114 returnTc (DataCons data_cons)
116 tc_con_decl (ConDecl name wkr_name ex_tvs ex_ctxt details src_loc)
117 = tcAddSrcLoc src_loc $
118 tcHsTyVars ex_tvs (kcConDetails new_or_data ex_ctxt details) $ \ ex_tyvars ->
119 tcHsTheta ex_ctxt `thenTc` \ ex_theta ->
121 VanillaCon btys -> tc_datacon ex_tyvars ex_theta btys
122 InfixCon bty1 bty2 -> tc_datacon ex_tyvars ex_theta [bty1,bty2]
123 RecCon fields -> tc_rec_con ex_tyvars ex_theta fields
126 tc_datacon ex_tyvars ex_theta btys
127 = mapTc tcHsType (map getBangType btys) `thenTc` \ arg_tys ->
128 mk_data_con ex_tyvars ex_theta (map getBangStrictness btys) arg_tys []
130 tc_rec_con ex_tyvars ex_theta fields
131 = checkTc (null ex_tyvars) (exRecConErr name) `thenTc_`
132 mapTc tc_field (fields `zip` allFieldLabelTags) `thenTc` \ field_labels_s ->
134 field_labels = concat field_labels_s
135 arg_stricts = [str | (ns, bty) <- fields,
136 let str = getBangStrictness bty,
137 n <- ns -- One for each. E.g x,y,z :: !Int
140 mk_data_con ex_tyvars ex_theta arg_stricts
141 (map fieldLabelType field_labels) field_labels
143 tc_field ((field_label_names, bty), tag)
144 = tcHsType (getBangType bty) `thenTc` \ field_ty ->
145 returnTc [mkFieldLabel (getName name) tycon field_ty tag | name <- field_label_names]
147 mk_data_con ex_tyvars ex_theta arg_stricts arg_tys fields
149 data_con = mkDataCon name arg_stricts fields
150 tyvars (thinContext arg_tys ctxt)
153 tycon data_con_id data_con_wrap_id
155 data_con_id = mkDataConId wkr_name data_con
156 data_con_wrap_id = mkDataConWrapId data_con
160 -- The context for a data constructor should be limited to
161 -- the type variables mentioned in the arg_tys
162 thinContext arg_tys ctxt
163 = filter in_arg_tys ctxt
165 arg_tyvars = tyVarsOfTypes arg_tys
166 in_arg_tys pred = not $ isEmptyVarSet $
167 tyVarsOfPred pred `intersectVarSet` arg_tyvars
171 %************************************************************************
173 \subsection{Errors and contexts}
175 %************************************************************************
180 = ptext SLIT("Can't combine named fields with locally-quantified type variables")
182 (ptext SLIT("In the declaration of data constructor") <+> ppr name)