module TcTyDecls (
tcTyDecl,
- tcConDecl
+ tcConDecl,
+ tcRecordSelectors
) where
import Ubiq{-uitous-}
-import HsSyn ( TyDecl(..), ConDecl(..), BangType(..), MonoType )
+import HsSyn ( TyDecl(..), ConDecl(..), BangType(..), HsExpr(..),
+ Match(..), GRHSsAndBinds(..), GRHS(..), OutPat(..),
+ HsBinds(..), HsLit, Stmt, Qual, ArithSeqInfo, PolyType,
+ Bind(..), MonoBinds(..), Sig,
+ MonoType )
import RnHsSyn ( RenamedTyDecl(..), RenamedConDecl(..) )
+import TcHsSyn ( TcHsBinds(..), TcIdOcc(..), mkHsTyLam )
import TcMonoType ( tcMonoTypeKind, tcMonoType, tcContext )
-import TcEnv ( tcLookupTyCon, tcLookupTyVar, tcLookupClass )
+import TcType ( tcInstTyVars, tcInstType )
+import TcEnv ( tcLookupTyCon, tcLookupTyVar, tcLookupClass,
+ newLocalId
+ )
import TcMonad
import TcKind ( TcKind, unifyKind, mkTcArrowKind, mkTcTypeKind )
-import Id ( mkDataCon, StrictnessMark(..) )
+import Id ( mkDataCon, dataConSig, mkRecordSelectorId,
+ dataConFieldLabels, StrictnessMark(..)
+ )
+import FieldLabel
import Kind ( Kind, mkArrowKind, mkBoxedTypeKind )
import SpecEnv ( SpecEnv(..), nullSpecEnv )
import Name ( getNameFullName, Name(..) )
import Pretty
-import TyCon ( TyCon, ConsVisible(..), NewOrData(..), mkSynTyCon, mkDataTyCon )
-import Type ( getTypeKind )
-import TyVar ( getTyVarKind )
-import Util ( panic )
-
+import TyCon ( TyCon, NewOrData(..), mkSynTyCon, mkDataTyCon, tyConDataCons )
+import Type ( getTypeKind, getTyVar, tyVarsOfTypes, eqTy, applyTyCon,
+ mkForAllTys, mkFunTy )
+import TyVar ( getTyVarKind, elementOfTyVarSet )
+import UniqSet ( emptyUniqSet, mkUniqSet, uniqSetToList, unionManyUniqSets, UniqSet(..) )
+import Util ( panic, equivClasses )
\end{code}
\begin{code}
(foldr mkTcArrowKind rhs_kind tyvar_kinds)
`thenTc_`
let
- -- Construct the tycon
+ -- Getting the TyCon's kind is a bit of a nuisance. We can't use the tycon_kind,
+ -- because that's a TcKind and may not yet be fully unified with other kinds.
+ -- We could have augmented the tycon environment with a knot-tied kind,
+ -- but the simplest thing to do seems to be to get the Kind by (lazily)
+ -- looking at the tyvars and rhs_ty.
result_kind, final_tycon_kind :: Kind -- NB not TcKind!
result_kind = getTypeKind rhs_ty
final_tycon_kind = foldr (mkArrowKind . getTyVarKind) result_kind rec_tyvars
+ -- Construct the tycon
tycon = mkSynTyCon (getItsUnique tycon_name)
(getNameFullName tycon_name)
final_tycon_kind
unifyKind tycon_kind
(foldr mkTcArrowKind mkTcTypeKind tyvar_kinds)
`thenTc_`
+
-- Walk the condecls
mapTc (tcConDecl rec_tycon rec_tyvars ctxt) con_decls
`thenTc` \ con_ids ->
ctxt
con_ids
derived_classes
- ConsVisible -- For now; if constrs are from pragma we are *abstract*
data_or_new
in
returnTc tycon
- where
- tc_derivs Nothing = returnNF_Tc []
- tc_derivs (Just ds) = mapNF_Tc tc_deriv ds
- tc_deriv name
- = tcLookupClass name `thenNF_Tc` \ (_, clas) ->
- returnNF_Tc clas
+tc_derivs Nothing = returnNF_Tc []
+tc_derivs (Just ds) = mapNF_Tc tc_deriv ds
+
+tc_deriv name
+ = tcLookupClass name `thenNF_Tc` \ (_, clas) ->
+ returnNF_Tc clas
\end{code}
+Generating selector bindings for record delarations
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+\begin{code}
+tcRecordSelectors :: TyCon -> TcM s ([Id], TcHsBinds s)
+tcRecordSelectors tycon
+ = mapAndUnzipTc (tcRecordSelector tycon) groups `thenTc` \ (ids, binds) ->
+ returnTc (ids, SingleBind (NonRecBind (foldr AndMonoBinds EmptyMonoBinds binds)))
+ where
+ data_cons = tyConDataCons tycon
+ fields = [ (con, field) | con <- data_cons,
+ field <- dataConFieldLabels con
+ ]
+
+ -- groups is list of fields that share a common name
+ groups = equivClasses cmp_name fields
+ cmp_name (_, field1) (_, field2)
+ = fieldLabelName field1 `cmp` fieldLabelName field2
+\end{code}
+
+We're going to build a record selector that looks like this:
+
+ data T a b c = T1 { op :: a, ...}
+ | T2 { op :: a, ...}
+ | T3
+
+ sel :: forall a b c. T a b c -> a
+ sel = /\ a b c -> \ T1 { sel = x } -> x
+ T2 { sel = 2 } -> x
+
+Note that the selector Id itself is used as the field
+label; it has to be an Id, you see!
+
+\begin{code}
+tcRecordSelector tycon fields@((first_con, first_field_label) : other_fields)
+ = panic "tcRecordSelector: don't typecheck"
+{-
+ = let
+ field_ty = fieldLabelType first_field_label
+ field_name = fieldLabelName first_field_label
+ other_tys = [fieldLabelType fl | (_, fl) <- fields]
+ (tyvars, _, _, _) = dataConSig first_con
+ -- tyvars of first_con may be free in first_ty
+ in
+
+ -- Check that all the fields in the group have the same type
+ -- This check assumes that all the constructors of a given
+ -- data type use the same type variables
+ checkTc (all (eqTy field_ty) other_tys)
+ (fieldTypeMisMatch field_name) `thenTc_`
+
+ -- Create an Id for the field itself
+ tcInstTyVars tyvars `thenNF_Tc` \ (tyvars', tyvar_tys, tenv) ->
+ tcInstType tenv field_ty `thenNF_Tc` \ field_ty' ->
+ let
+ data_ty' = applyTyCon tycon tyvar_tys
+ in
+ newLocalId SLIT("x") field_ty' `thenNF_Tc` \ field_id ->
+ newLocalId SLIT("r") data_ty' `thenNF_Tc` \ record_id ->
+
+ -- Now build the selector
+ let
+ tycon_src_loc = getSrcLoc tycon
+
+ selector_ty = mkForAllTys tyvars' $
+ mkFunTy data_ty' $
+ field_ty'
+
+ selector_id = mkRecordSelectorId first_field_label selector_ty
+
+ -- HsSyn is dreadfully verbose for defining the selector!
+ selector_rhs = mkHsTyLam tyvars' $
+ HsLam $
+ PatMatch (VarPat record_id) $
+ GRHSMatch $
+ GRHSsAndBindsOut [OtherwiseGRHS selector_body tycon_src_loc]
+ EmptyBinds field_ty'
+
+ selector_body = HsCase (HsVar record_id) (map mk_match fields) tycon_src_loc
+
+ mk_match (con_id, field_label)
+ = PatMatch (RecPat con_id data_ty' [(selector_id, VarPat field_id, False)]) $
+ GRHSMatch $
+ GRHSsAndBindsOut [OtherwiseGRHS (HsVar field_id)
+ (getSrcLoc (fieldLabelName field_label))]
+ EmptyBinds
+ field_ty'
+ in
+ returnTc (selector_id, VarMonoBind selector_id selector_rhs)
+-}
+\end{code}
Constructors
~~~~~~~~~~~~
tcConDecl :: TyCon -> [TyVar] -> [(Class,Type)] -> RenamedConDecl -> TcM s Id
tcConDecl tycon tyvars ctxt (ConDecl name btys src_loc)
+ = tcDataCon tycon tyvars ctxt name btys src_loc
+
+tcConDecl tycon tyvars ctxt (ConOpDecl bty1 op bty2 src_loc)
+ = tcDataCon tycon tyvars ctxt op [bty1,bty2] src_loc
+
+tcConDecl tycon tyvars ctxt (NewConDecl name ty src_loc)
= tcAddSrcLoc src_loc $
- let
- (stricts, tys) = sep_bangs btys
- in
- mapTc tcMonoType tys `thenTc` \ arg_tys ->
+ tcMonoType ty `thenTc` \ arg_ty ->
let
data_con = mkDataCon (getItsUnique name)
(getNameFullName name)
- stricts
+ [NotMarkedStrict]
+ [{- No labelled fields -}]
tyvars
- [] -- ToDo: ctxt; limited to tyvars in arg_tys
- arg_tys
+ ctxt
+ [arg_ty]
tycon
-- nullSpecEnv
in
returnTc data_con
-tcConDecl tycon tyvars ctxt (ConOpDecl bty1 op bty2 src_loc)
+tcConDecl tycon tyvars ctxt (RecConDecl name fields src_loc)
= tcAddSrcLoc src_loc $
+ mapTc tcField fields `thenTc` \ field_label_infos_s ->
let
- (stricts, tys) = sep_bangs [bty1, bty2]
- in
- mapTc tcMonoType tys `thenTc` \ arg_tys ->
- let
- data_con = mkDataCon (getItsUnique op)
- (getNameFullName op)
+ field_label_infos = concat field_label_infos_s
+ stricts = [strict | (_, _, strict) <- field_label_infos]
+ arg_tys = [ty | (_, ty, _) <- field_label_infos]
+
+ field_labels = [ mkFieldLabel name ty tag
+ | ((name, ty, _), tag) <- field_label_infos `zip` allFieldLabelTags
+ ]
+
+ data_con = mkDataCon (getItsUnique name)
+ (getNameFullName name)
stricts
+ field_labels
tyvars
- [] -- ToDo: ctxt
+ (thinContext arg_tys ctxt)
arg_tys
tycon
-- nullSpecEnv
in
returnTc data_con
-tcConDecl tycon tyvars ctxt (NewConDecl name ty src_loc)
+tcField (field_label_names, bty)
+ = tcMonoType (get_ty bty) `thenTc` \ field_ty ->
+ returnTc [(name, field_ty, get_strictness bty) | name <- field_label_names]
+
+tcDataCon tycon tyvars ctxt name btys src_loc
= tcAddSrcLoc src_loc $
- tcMonoType ty `thenTc` \ arg_ty ->
+ let
+ stricts = map get_strictness btys
+ tys = map get_ty btys
+ in
+ mapTc tcMonoType tys `thenTc` \ arg_tys ->
let
data_con = mkDataCon (getItsUnique name)
(getNameFullName name)
- [NotMarkedStrict]
+ stricts
+ [{- No field labels -}]
tyvars
- [] -- ToDo: ctxt
- [arg_ty]
+ (thinContext arg_tys ctxt)
+ arg_tys
tycon
-- nullSpecEnv
in
returnTc data_con
-tcConDecl tycon tyvars ctxt (RecConDecl con fields src_loc)
- = panic "tcConDecls:RecConDecl"
-
-
-sep_bangs btys
- = unzip (map sep_bang btys)
- where
- sep_bang (Banged ty) = (MarkedStrict, ty)
- sep_bang (Unbanged ty) = (NotMarkedStrict, ty)
+-- The context for a data constructor should be limited to
+-- the type variables mentioned in the arg_tys
+thinContext arg_tys ctxt
+ = filter in_arg_tys ctxt
+ where
+ arg_tyvars = tyVarsOfTypes arg_tys
+ in_arg_tys (clas,ty) = getTyVar "tcDataCon" ty `elementOfTyVarSet` arg_tyvars
+
+get_strictness (Banged ty) = MarkedStrict
+get_strictness (Unbanged ty) = NotMarkedStrict
+
+get_ty (Banged ty) = ty
+get_ty (Unbanged ty) = ty
\end{code}
tyNewCtxt tycon_name sty
= ppCat [ppStr "In the newtype declaration for", ppr sty tycon_name]
+
+fieldTypeMisMatch field_name sty
+ = ppSep [ppStr "Declared types differ for field", ppr sty field_name]
\end{code}
projects / ghc-hetmet.git / blobdiff