\begin{code}
module TcTyClsDecls (
- tcTyAndClassDecls1
+ tcTyAndClassDecls
) where
#include "HsVersions.h"
-import HsSyn ( HsDecl(..), TyDecl(..), ClassDecl(..),
- HsType(..), HsTyVar,
- ConDecl(..), ConDetails(..), BangType(..),
- Sig(..),
- hsDeclName
+import HsSyn ( TyClDecl(..), HsConDetails(..), HsTyVarBndr(..),
+ ConDecl(..), Sig(..), BangType(..), HsBang(..),
+ tyClDeclTyVars, getBangType, getBangStrictness
)
-import RnHsSyn ( RenamedHsDecl )
-import RnEnv ( listTyCon_name, tupleTyCon_name ) -- ToDo: move these
-import BasicTypes ( RecFlag(..), Arity )
-
-import TcMonad
-import Inst ( InstanceMapper )
-import TcClassDcl ( tcClassDecl1 )
-import TcEnv ( TcIdOcc(..), GlobalValueEnv, tcExtendTyConEnv, tcExtendClassEnv )
-import TcType ( TcKind, newKindVar, newKindVars, kindToTcKind )
-import TcTyDecls ( tcTyDecl )
-import TcMonoType ( tcTyVarScope )
-
-import TyCon ( tyConKind, tyConArity, isSynTyCon )
-import Class ( Class, classBigSig )
-import Var ( tyVarKind )
-import Bag
-import Digraph ( stronglyConnComp, SCC(..) )
-import Name ( Name, NamedThing(..), getSrcLoc, isTvOcc, nameOccName )
+import RnHsSyn ( RenamedTyClDecl, RenamedConDecl )
+import BasicTypes ( RecFlag(..), NewOrData(..), StrictnessMark(..) )
+import HscTypes ( implicitTyThings )
+import BuildTyCl ( buildClass, buildAlgTyCon, buildSynTyCon, buildDataCon )
+import TcRnMonad
+import TcEnv ( TcTyThing(..), TyThing(..),
+ tcLookup, tcLookupGlobal, tcExtendGlobalEnv,
+ tcExtendRecEnv, tcLookupTyVar )
+import TcTyDecls ( calcTyConArgVrcs, calcRecFlags, calcCycleErrs )
+import TcClassDcl ( tcClassSigs, tcAddDeclCtxt )
+import TcHsType ( kcHsTyVars, kcHsLiftedSigType, kcHsSigType, kcCheckHsType,
+ kcHsContext, tcTyVarBndrs, tcHsKindedType, tcHsKindedContext )
+import TcMType ( newKindVar, checkValidTheta, checkValidType, checkFreeness,
+ UserTypeCtxt(..), SourceTyCtxt(..) )
+import TcUnify ( unifyKind )
+import TcType ( TcKind, ThetaType, TcType,
+ mkArrowKind, liftedTypeKind,
+ tcSplitSigmaTy, tcEqType )
+import Type ( splitTyConApp_maybe )
+import PprType ( pprThetaArrow, pprParendType )
+import FieldLabel ( fieldLabelName, fieldLabelType )
+import Generics ( validGenericMethodType, canDoGenerics )
+import Class ( Class, className, classTyCon, DefMeth(..), classBigSig )
+import TyCon ( TyCon, ArgVrcs, DataConDetails(..),
+ tyConDataCons, mkForeignTyCon, isProductTyCon, isRecursiveTyCon,
+ tyConTheta, getSynTyConDefn, tyConDataCons, isSynTyCon, tyConName )
+import DataCon ( DataCon, dataConWrapId, dataConName, dataConSig, dataConFieldLabels )
+import Var ( TyVar, idType, idName )
+import Name ( Name, getSrcLoc )
import Outputable
-import Maybes ( mapMaybe )
-import UniqSet ( UniqSet, emptyUniqSet,
- unitUniqSet, unionUniqSets,
- unionManyUniqSets, uniqSetToList )
-import SrcLoc ( SrcLoc )
-import TyCon ( TyCon )
-import Unique ( Unique, Uniquable(..) )
-import Util ( panic{-, pprTrace-} )
-
+import Util ( zipLazy, isSingleton, notNull )
+import ListSetOps ( equivClasses )
+import CmdLineOpts ( DynFlag( Opt_GlasgowExts, Opt_Generics, Opt_UnboxStrictFields ) )
\end{code}
-The main function
-~~~~~~~~~~~~~~~~~
-\begin{code}
-tcTyAndClassDecls1 :: GlobalValueEnv -> InstanceMapper -- Knot tying stuff
- -> [RenamedHsDecl]
- -> TcM s (TcEnv s)
-tcTyAndClassDecls1 unf_env inst_mapper decls
- = sortByDependency decls `thenTc` \ groups ->
- tcGroups unf_env inst_mapper groups
+%************************************************************************
+%* *
+\subsection{Type checking for type and class declarations}
+%* *
+%************************************************************************
-tcGroups unf_env inst_mapper []
- = tcGetEnv `thenNF_Tc` \ env ->
- returnTc env
+Dealing with a group
+~~~~~~~~~~~~~~~~~~~~
+Consider a mutually-recursive group, binding
+a type constructor T and a class C.
-tcGroups unf_env inst_mapper (group:groups)
- = tcGroup unf_env inst_mapper group `thenTc` \ (group_tycons, group_classes) ->
+Step 1: getInitialKind
+ Construct a KindEnv by binding T and C to a kind variable
- -- Extend the environment using the new tycons and classes
- tcExtendTyConEnv [(getName tycon, (kindToTcKind (tyConKind tycon),
- if isSynTyCon tycon then Just (tyConArity tycon) else Nothing,
- tycon))
- | tycon <- group_tycons] $
+Step 2: kcTyClDecl
+ In that environment, do a kind check
- tcExtendClassEnv [(getName clas, (classKind clas, clas))
- | clas <- group_classes] $
+Step 3: Zonk the kinds
+Step 4: buildTyConOrClass
+ Construct an environment binding T to a TyCon and C to a Class.
+ a) Their kinds comes from zonking the relevant kind variable
+ b) Their arity (for synonyms) comes direct from the decl
+ c) The funcional dependencies come from the decl
+ d) The rest comes a knot-tied binding of T and C, returned from Step 4
+ e) The variances of the tycons in the group is calculated from
+ the knot-tied stuff
- -- Do the remaining groups
- tcGroups unf_env inst_mapper groups
- where
- classKind clas = map (kindToTcKind . tyVarKind) tyvars
- where
- (tyvars, _, _, _, _) = classBigSig clas
-\end{code}
+Step 5: tcTyClDecl1
+ In this environment, walk over the decls, constructing the TyCons and Classes.
+ This uses in a strict way items (a)-(c) above, which is why they must
+ be constructed in Step 4. Feed the results back to Step 4.
+ For this step, pass the is-recursive flag as the wimp-out flag
+ to tcTyClDecl1.
+
-Dealing with a group
-~~~~~~~~~~~~~~~~~~~~
-
-Notice the uses of @zipLazy@, which makes sure
-that the knot-tied TyVars, TyCons and Classes aren't looked at too early.
-
-
-\begin{code}
-tcGroup :: GlobalValueEnv -> InstanceMapper -> SCC RenamedHsDecl -> TcM s ([TyCon], [Class])
-tcGroup unf_env inst_mapper scc
- = -- TIE THE KNOT
- fixTc ( \ ~(rec_tycons, rec_classes) ->
-
- -- EXTEND TYPE AND CLASS ENVIRONMENTS
- let
- mk_tycon_bind (name, arity) = newKindVar `thenNF_Tc` \ kind ->
- returnNF_Tc (name, (kind, arity, find name rec_tycons))
-
- mk_class_bind (name, arity) = newKindVars arity `thenNF_Tc` \ kinds ->
- returnNF_Tc (name, (kinds, find name rec_classes))
-
- find name [] = pprPanic "tcGroup" (ppr name)
- find name (thing:things) | name == getName thing = thing
- | otherwise = find name things
-
- in
- mapNF_Tc mk_tycon_bind tycon_names_w_arities `thenNF_Tc` \ tycon_binds ->
- mapNF_Tc mk_class_bind class_names_w_arities `thenNF_Tc` \ class_binds ->
- tcExtendTyConEnv tycon_binds $
- tcExtendClassEnv class_binds $
-
- -- DEAL WITH TYPE VARIABLES
- tcTyVarScope tyvar_names ( \ tyvars ->
-
- -- DEAL WITH THE DEFINITIONS THEMSELVES
- foldlTc (tcDecl is_rec_group unf_env inst_mapper) ([], []) decls
- ) `thenTc` \ (tycons, classes) ->
-
- returnTc (tycons, classes)
- )
- where
- is_rec_group = case scc of
- AcyclicSCC _ -> NonRecursive
- CyclicSCC _ -> Recursive
+Step 6: Extend environment
+ We extend the type environment with bindings not only for the TyCons and Classes,
+ but also for their "implicit Ids" like data constructors and class selectors
- decls = case scc of
- AcyclicSCC decl -> [decl]
- CyclicSCC decls -> decls
+Step 7: checkValidTyCl
+ For a recursive group only, check all the decls again, just
+ to check all the side conditions on validity. We could not
+ do this before because we were in a mutually recursive knot.
- (tyvar_names, tycon_names_w_arities, class_names_w_arities) = get_binders decls
-\end{code}
-Dealing with one decl
-~~~~~~~~~~~~~~~~~~~~~
-\begin{code}
-tcDecl :: RecFlag -- True => recursive group
- -> GlobalValueEnv -> InstanceMapper
- -> ([TyCon], [Class]) -- Accumulating parameter
- -> RenamedHsDecl
- -> TcM s ([TyCon], [Class])
-
-tcDecl is_rec_group unf_env inst_mapper (tycons, classes) (TyD decl)
- = tcTyDecl is_rec_group decl `thenTc` \ tycon ->
- returnTc (tycon:tycons, classes)
-
-tcDecl is_rec_group unf_env inst_mapper (tycons, classes) (ClD decl)
- = tcClassDecl1 unf_env inst_mapper decl `thenTc` \ clas ->
- returnTc (tycons, clas:classes)
-\end{code}
+The knot-tying parameters: @rec_details_list@ is an alist mapping @Name@s to
+@TyThing@s. @rec_vrcs@ is a finite map from @Name@s to @ArgVrcs@s.
-Dependency analysis
-~~~~~~~~~~~~~~~~~~~
\begin{code}
-sortByDependency :: [RenamedHsDecl] -> TcM s [SCC RenamedHsDecl]
-sortByDependency decls
- = let -- CHECK FOR CLASS CYCLES
- cls_sccs = stronglyConnComp (mapMaybe mk_cls_edges decls)
- cls_cycles = [ decls | CyclicSCC decls <- cls_sccs]
- in
- checkTc (null cls_cycles) (classCycleErr cls_cycles) `thenTc_`
-
- let -- CHECK FOR SYNONYM CYCLES
- syn_sccs = stronglyConnComp (filter is_syn_decl edges)
- syn_cycles = [ decls | CyclicSCC decls <- syn_sccs]
-
- in
- checkTc (null syn_cycles) (typeCycleErr syn_cycles) `thenTc_`
-
- -- DO THE MAIN DEPENDENCY ANALYSIS
- let
- decl_sccs = stronglyConnComp edges
- in
- returnTc decl_sccs
+tcTyAndClassDecls :: [RenamedTyClDecl]
+ -> TcM TcGblEnv -- Input env extended by types and classes
+ -- and their implicit Ids,DataCons
+tcTyAndClassDecls decls
+ = do { -- First check for cyclic type synonysm or classes
+ -- See notes with checkCycleErrs
+ checkCycleErrs decls
+
+ ; tyclss <- fixM (\ rec_tyclss ->
+ do { lcl_things <- mappM getInitialKind decls
+ -- Extend the local env with kinds, and
+ -- the global env with the knot-tied results
+ ; let { gbl_things = mkGlobalThings decls rec_tyclss }
+ ; tcExtendRecEnv gbl_things lcl_things $ do
+
+ -- The local type environment is populated with
+ -- {"T" -> ARecTyCon k, ...}
+ -- and the global type envt with
+ -- {"T" -> ATyCon T, ...}
+ -- where k is T's (unzonked) kind
+ -- T is the loop-tied TyCon itself
+ -- We must populate the environment with the loop-tied T's right
+ -- away, because the kind checker may "fault in" some type
+ -- constructors that recursively mention T
+
+ -- Kind-check the declarations, returning kind-annotated decls
+ { kc_decls <- mappM kcTyClDecl decls
+
+ -- Calculate variances and rec-flag
+ ; let { calc_vrcs = calcTyConArgVrcs rec_tyclss
+ ; calc_rec = calcRecFlags rec_tyclss }
+
+ ; mappM (tcTyClDecl calc_vrcs calc_rec) kc_decls
+ }})
+ -- Finished with knot-tying now
+ -- Extend the environment with the finished things
+ ; tcExtendGlobalEnv tyclss $ do
+
+ -- Perform the validity check
+ { traceTc (text "ready for validity check")
+ ; mappM_ checkValidTyCl decls
+ ; traceTc (text "done")
+
+ -- Add the implicit things;
+ -- we want them in the environment because
+ -- they may be mentioned in interface files
+ ; let { implicit_things = concatMap implicitTyThings tyclss }
+ ; traceTc ((text "Adding" <+> ppr tyclss) $$ (text "and" <+> ppr implicit_things))
+ ; tcExtendGlobalEnv implicit_things getGblEnv
+ }}
+
+mkGlobalThings :: [RenamedTyClDecl] -- The decls
+ -> [TyThing] -- Knot-tied, in 1-1 correspondence with the decls
+ -> [(Name,TyThing)]
+-- Driven by the Decls, and treating the TyThings lazily
+-- make a TypeEnv for the new things
+mkGlobalThings decls things
+ = map mk_thing (decls `zipLazy` things)
where
- edges = mapMaybe mk_edges decls
-
-is_syn_decl (TyD (TySynonym _ _ _ _), _, _) = True
-is_syn_decl _ = False
-
-is_cls_decl (ClD _, _, _) = True
-is_cls_decl other = False
+ mk_thing (ClassDecl {tcdName = name}, ~(AClass cl)) = (name, AClass cl)
+ mk_thing (decl, ~(ATyCon tc)) = (tcdName decl, ATyCon tc)
\end{code}
-Edges in Type/Class decls
-~~~~~~~~~~~~~~~~~~~~~~~~~
-\begin{code}
--- mk_cls_edges looks only at the context of class decls
--- Its used when we are figuring out if there's a cycle in the
--- superclass hierarchy
-mk_cls_edges :: RenamedHsDecl -> Maybe (RenamedHsDecl, Unique, [Unique])
+%************************************************************************
+%* *
+ Kind checking
+%* *
+%************************************************************************
-mk_cls_edges decl@(ClD (ClassDecl ctxt name _ _ _ _ _ _ _))
- = Just (decl, getUnique name, map (getUnique . fst) ctxt)
-mk_cls_edges other_decl
- = Nothing
+We need to kind check all types in the mutually recursive group
+before we know the kind of the type variables. For example:
+class C a where
+ op :: D b => a -> b -> b
-mk_edges :: RenamedHsDecl -> Maybe (RenamedHsDecl, Unique, [Unique])
+class D c where
+ bop :: (Monad c) => ...
-mk_edges decl@(TyD (TyData _ ctxt name _ condecls derivs _ _))
- = Just (decl, getUnique name, uniqSetToList (get_ctxt ctxt `unionUniqSets`
- get_cons condecls `unionUniqSets`
- get_deriv derivs))
+Here, the kind of the locally-polymorphic type variable "b"
+depends on *all the uses of class D*. For example, the use of
+Monad c in bop's type signature means that D must have kind Type->Type.
-mk_edges decl@(TyD (TySynonym name _ rhs _))
- = Just (decl, getUnique name, uniqSetToList (get_ty rhs))
+\begin{code}
+------------------------------------------------------------------------
+getInitialKind :: TyClDecl Name -> TcM (Name, TcTyThing)
-mk_edges decl@(ClD (ClassDecl ctxt name _ sigs _ _ _ _ _))
- = Just (decl, getUnique name, uniqSetToList (get_ctxt ctxt `unionUniqSets`
- get_sigs sigs))
+-- Note the lazy pattern match on the ATyCon etc
+-- Exactly the same reason as the zipLay above
-mk_edges other_decl = Nothing
+getInitialKind (TyData {tcdName = name})
+ = newKindVar `thenM` \ kind ->
+ returnM (name, ARecTyCon kind)
-get_ctxt ctxt = unionManyUniqSets (map (set_name.fst) ctxt)
+getInitialKind (TySynonym {tcdName = name})
+ = newKindVar `thenM` \ kind ->
+ returnM (name, ARecTyCon kind)
-get_deriv Nothing = emptyUniqSet
-get_deriv (Just clss) = unionManyUniqSets (map set_name clss)
+getInitialKind (ClassDecl {tcdName = name})
+ = newKindVar `thenM` \ kind ->
+ returnM (name, ARecClass kind)
-get_cons cons = unionManyUniqSets (map get_con cons)
-get_con (ConDecl _ _ ctxt details _)
- = get_ctxt ctxt `unionUniqSets` get_con_details details
+------------------------------------------------------------------------
+kcTyClDecl :: RenamedTyClDecl -> TcM RenamedTyClDecl
-get_con_details (VanillaCon btys) = unionManyUniqSets (map get_bty btys)
-get_con_details (InfixCon bty1 bty2) = unionUniqSets (get_bty bty1) (get_bty bty2)
-get_con_details (NewCon ty) = get_ty ty
-get_con_details (RecCon nbtys) = unionManyUniqSets (map (get_bty.snd) nbtys)
+kcTyClDecl decl@(TySynonym {tcdSynRhs = rhs})
+ = do { res_kind <- newKindVar
+ ; kcTyClDeclBody decl res_kind $ \ tvs' ->
+ do { rhs' <- kcCheckHsType rhs res_kind
+ ; return (decl {tcdTyVars = tvs', tcdSynRhs = rhs'}) } }
-get_bty (Banged ty) = get_ty ty
-get_bty (Unbanged ty) = get_ty ty
+kcTyClDecl decl@(TyData {tcdND = new_or_data, tcdCtxt = ctxt, tcdCons = cons})
+ = kcTyClDeclBody decl liftedTypeKind $ \ tvs' ->
+ do { ctxt' <- kcHsContext ctxt
+ ; cons' <- mappM kc_con_decl cons
+ ; return (decl {tcdTyVars = tvs', tcdCtxt = ctxt', tcdCons = cons'}) }
+ where
+ kc_con_decl (ConDecl name ex_tvs ex_ctxt details loc)
+ = kcHsTyVars ex_tvs $ \ ex_tvs' ->
+ do { ex_ctxt' <- kcHsContext ex_ctxt
+ ; details' <- kc_con_details details
+ ; return (ConDecl name ex_tvs' ex_ctxt' details' loc)}
+
+ kc_con_details (PrefixCon btys)
+ = do { btys' <- mappM kc_arg_ty btys ; return (PrefixCon btys') }
+ kc_con_details (InfixCon bty1 bty2)
+ = do { bty1' <- kc_arg_ty bty1; bty2' <- kc_arg_ty bty2; return (InfixCon bty1' bty2') }
+ kc_con_details (RecCon fields)
+ = do { fields' <- mappM kc_field fields; return (RecCon fields') }
+
+ kc_field (fld, bty) = do { bty' <- kc_arg_ty bty ; return (fld, bty') }
+
+ kc_arg_ty (BangType str ty) = do { ty' <- kc_arg_ty_body ty; return (BangType str ty') }
+ kc_arg_ty_body = case new_or_data of
+ DataType -> kcHsSigType
+ NewType -> kcHsLiftedSigType
+ -- Can't allow an unlifted type for newtypes, because we're effectively
+ -- going to remove the constructor while coercing it to a lifted type.
+
+kcTyClDecl decl@(ClassDecl {tcdCtxt = ctxt, tcdSigs = sigs})
+ = kcTyClDeclBody decl liftedTypeKind $ \ tvs' ->
+ do { ctxt' <- kcHsContext ctxt
+ ; sigs' <- mappM kc_sig sigs
+ ; return (decl {tcdTyVars = tvs', tcdCtxt = ctxt', tcdSigs = sigs'}) }
+ where
+ kc_sig (Sig nm op_ty loc) = do { op_ty' <- kcHsLiftedSigType op_ty
+ ; return (Sig nm op_ty' loc) }
+ kc_sig other_sig = return other_sig
+
+kcTyClDecl decl@(ForeignType {})
+ = return decl
+
+kcTyClDeclBody :: RenamedTyClDecl -> TcKind
+ -> ([HsTyVarBndr Name] -> TcM a)
+ -> TcM a
+ -- Extend the env with bindings for the tyvars, taken from
+ -- the kind of the tycon/class. Give it to the thing inside, and
+ -- check the result kind matches
+kcTyClDeclBody decl res_kind thing_inside
+ = tcAddDeclCtxt decl $
+ kcHsTyVars (tyClDeclTyVars decl) $ \ kinded_tvs ->
+ do { tc_ty_thing <- tcLookup (tcdName decl)
+ ; let { tc_kind = case tc_ty_thing of
+ ARecClass k -> k
+ ARecTyCon k -> k
+ }
+ ; unifyKind tc_kind (foldr (mkArrowKind . kindedTyVarKind)
+ res_kind kinded_tvs)
+ ; thing_inside kinded_tvs }
+
+kindedTyVarKind (KindedTyVar _ k) = k
+\end{code}
-get_ty (MonoTyVar name)
- = if isTvOcc (nameOccName name) then emptyUniqSet else set_name name
-get_ty (MonoTyApp ty1 ty2)
- = unionUniqSets (get_ty ty1) (get_ty ty2)
-get_ty (MonoFunTy ty1 ty2)
- = unionUniqSets (get_ty ty1) (get_ty ty2)
-get_ty (MonoListTy ty)
- = set_name listTyCon_name `unionUniqSets` get_ty ty
-get_ty (MonoTupleTy tys boxed)
- = set_name (tupleTyCon_name boxed (length tys)) `unionUniqSets` get_tys tys
-get_ty (HsForAllTy _ ctxt mty)
- = get_ctxt ctxt `unionUniqSets` get_ty mty
-get_ty other = panic "TcTyClsDecls:get_ty"
-get_tys tys
- = unionManyUniqSets (map get_ty tys)
+%************************************************************************
+%* *
+\subsection{Type checking}
+%* *
+%************************************************************************
-get_sigs sigs
- = unionManyUniqSets (map get_sig sigs)
- where
- get_sig (ClassOpSig _ _ ty _) = get_ty ty
- get_sig other = panic "TcTyClsDecls:get_sig"
+\begin{code}
+tcTyClDecl :: (Name -> ArgVrcs) -> (Name -> RecFlag)
+ -> RenamedTyClDecl -> TcM TyThing
-set_name name = unitUniqSet (getUnique name)
+tcTyClDecl calc_vrcs calc_isrec decl
+ = tcAddDeclCtxt decl (tcTyClDecl1 calc_vrcs calc_isrec decl)
-set_to_bag set = listToBag (uniqSetToList set)
+tcTyClDecl1 calc_vrcs calc_isrec
+ (TySynonym {tcdName = tc_name, tcdTyVars = tvs, tcdSynRhs = rhs_ty})
+ = tcTyVarBndrs tvs $ \ tvs' -> do
+ { rhs_ty' <- tcHsKindedType rhs_ty
+ ; return (ATyCon (buildSynTyCon tc_name tvs' rhs_ty' arg_vrcs)) }
+ where
+ arg_vrcs = calc_vrcs tc_name
+
+tcTyClDecl1 calc_vrcs calc_isrec
+ (TyData {tcdND = new_or_data, tcdCtxt = ctxt, tcdTyVars = tvs,
+ tcdName = tc_name, tcdCons = cons})
+ = tcTyVarBndrs tvs $ \ tvs' -> do
+ { ctxt' <- tcHsKindedContext ctxt
+ ; want_generic <- doptM Opt_Generics
+ ; tycon <- fixM (\ tycon -> do
+ { cons' <- mappM (tcConDecl new_or_data tycon tvs' ctxt') cons
+ ; buildAlgTyCon new_or_data tc_name tvs' ctxt'
+ (DataCons cons') arg_vrcs is_rec
+ (want_generic && canDoGenerics cons')
+ })
+ ; return (ATyCon tycon)
+ }
+ where
+ arg_vrcs = calc_vrcs tc_name
+ is_rec = calc_isrec tc_name
+
+tcTyClDecl1 calc_vrcs calc_isrec
+ (ClassDecl {tcdName = class_name, tcdTyVars = tvs,
+ tcdCtxt = ctxt, tcdMeths = meths,
+ tcdFDs = fundeps, tcdSigs = sigs} )
+ = tcTyVarBndrs tvs $ \ tvs' -> do
+ { ctxt' <- tcHsKindedContext ctxt
+ ; fds' <- mappM tc_fundep fundeps
+ ; sig_stuff <- tcClassSigs class_name sigs meths
+ ; clas <- fixM (\ clas ->
+ let -- This little knot is just so we can get
+ -- hold of the name of the class TyCon, which we
+ -- need to look up its recursiveness and variance
+ tycon_name = tyConName (classTyCon clas)
+ tc_isrec = calc_isrec tycon_name
+ tc_vrcs = calc_vrcs tycon_name
+ in
+ buildClass class_name tvs' ctxt' fds'
+ sig_stuff tc_isrec tc_vrcs)
+ ; return (AClass clas) }
+ where
+ tc_fundep (tvs1, tvs2) = do { tvs1' <- mappM tcLookupTyVar tvs1 ;
+ ; tvs2' <- mappM tcLookupTyVar tvs2 ;
+ ; return (tvs1', tvs2') }
+
+
+tcTyClDecl1 calc_vrcs calc_isrec
+ (ForeignType {tcdName = tc_name, tcdExtName = tc_ext_name})
+ = returnM (ATyCon (mkForeignTyCon tc_name tc_ext_name liftedTypeKind 0 []))
+
+-----------------------------------
+tcConDecl :: NewOrData -> TyCon -> [TyVar] -> ThetaType
+ -> RenamedConDecl -> TcM DataCon
+
+tcConDecl new_or_data tycon tyvars ctxt
+ (ConDecl name ex_tvs ex_ctxt details src_loc)
+ = addSrcLoc src_loc $
+ tcTyVarBndrs ex_tvs $ \ ex_tvs' -> do
+ { ex_ctxt' <- tcHsKindedContext ex_ctxt
+ ; unbox_strict <- doptM Opt_UnboxStrictFields
+ ; let
+ tc_datacon field_lbls btys
+ = do { arg_tys <- mappM (tcHsKindedType . getBangType) btys
+ ; buildDataCon name
+ (argStrictness unbox_strict tycon btys arg_tys)
+ field_lbls
+ tyvars ctxt ex_tvs' ex_ctxt'
+ arg_tys tycon }
+ ; case details of
+ PrefixCon btys -> tc_datacon [] btys
+ InfixCon bty1 bty2 -> tc_datacon [] [bty1,bty2]
+ RecCon fields -> do { checkTc (null ex_tvs') (exRecConErr name)
+ ; let { (field_names, btys) = unzip fields }
+ ; tc_datacon field_names btys } }
+
+argStrictness :: Bool -- True <=> -funbox-strict_fields
+ -> TyCon -> [BangType Name]
+ -> [TcType] -> [StrictnessMark]
+argStrictness unbox_strict tycon btys arg_tys
+ = zipWith (chooseBoxingStrategy unbox_strict tycon)
+ arg_tys
+ (map getBangStrictness btys ++ repeat HsNoBang)
+
+-- We attempt to unbox/unpack a strict field when either:
+-- (i) The field is marked '!!', or
+-- (ii) The field is marked '!', and the -funbox-strict-fields flag is on.
+
+chooseBoxingStrategy :: Bool -> TyCon -> TcType -> HsBang -> StrictnessMark
+chooseBoxingStrategy unbox_strict_fields tycon arg_ty bang
+ = case bang of
+ HsNoBang -> NotMarkedStrict
+ HsStrict | unbox_strict_fields && can_unbox -> MarkedUnboxed
+ HsUnbox | can_unbox -> MarkedUnboxed
+ other -> MarkedStrict
+ where
+ can_unbox = case splitTyConApp_maybe arg_ty of
+ Nothing -> False
+ Just (arg_tycon, _) -> not (isRecursiveTyCon tycon) &&
+ isProductTyCon arg_tycon
\end{code}
+%************************************************************************
+%* *
+\subsection{Dependency analysis}
+%* *
+%************************************************************************
-get_binders
-~~~~~~~~~~~
-Extract *binding* names from type and class decls. Type variables are
-bound in type, data, newtype and class declarations,
- *and* the polytypes in the class op sigs.
- *and* the existentially quantified contexts in datacon decls
+Validity checking is done once the mutually-recursive knot has been
+tied, so we can look at things freely.
-Why do we need to grab all these type variables at once, including
-those locally-quantified type variables in class op signatures?
+\begin{code}
+checkCycleErrs :: [TyClDecl Name] -> TcM ()
+checkCycleErrs tyclss
+ | null syn_cycles && null cls_cycles
+ = return ()
+ | otherwise
+ = do { mappM_ recSynErr syn_cycles
+ ; mappM_ recClsErr cls_cycles
+ ; failM } -- Give up now, because later checkValidTyCl
+ -- will loop if the synonym is recursive
+ where
+ (syn_cycles, cls_cycles) = calcCycleErrs tyclss
+
+checkValidTyCl :: RenamedTyClDecl -> TcM ()
+-- We do the validity check over declarations, rather than TyThings
+-- only so that we can add a nice context with tcAddDeclCtxt
+checkValidTyCl decl
+ = tcAddDeclCtxt decl $
+ do { thing <- tcLookupGlobal (tcdName decl)
+ ; traceTc (text "Validity of" <+> ppr thing)
+ ; case thing of
+ ATyCon tc -> checkValidTyCon tc
+ AClass cl -> checkValidClass cl
+ ; traceTc (text "Done validity of" <+> ppr thing)
+ }
+
+-------------------------
+checkValidTyCon :: TyCon -> TcM ()
+checkValidTyCon tc
+ | isSynTyCon tc
+ = checkValidType syn_ctxt syn_rhs
+ | otherwise
+ = -- Check the context on the data decl
+ checkValidTheta (DataTyCtxt name) (tyConTheta tc) `thenM_`
+
+ -- Check arg types of data constructors
+ mappM_ checkValidDataCon data_cons `thenM_`
+
+ -- Check that fields with the same name share a type
+ mappM_ check_fields groups
- [Incidentally, this only works because the names are all unique by now.]
+ where
+ syn_ctxt = TySynCtxt name
+ name = tyConName tc
+ (_, syn_rhs) = getSynTyConDefn tc
+ data_cons = tyConDataCons tc
+
+ fields = [field | con <- data_cons, field <- dataConFieldLabels con]
+ groups = equivClasses cmp_name fields
+ cmp_name field1 field2 = fieldLabelName field1 `compare` fieldLabelName field2
+
+ check_fields fields@(first_field_label : other_fields)
+ -- These fields all have the same name, but are from
+ -- different constructors in the data type
+ = -- Check that all the fields in the group have the same type
+ -- NB: this check assumes that all the constructors of a given
+ -- data type use the same type variables
+ checkTc (all (tcEqType field_ty) other_tys) (fieldTypeMisMatch field_name)
+ where
+ field_ty = fieldLabelType first_field_label
+ field_name = fieldLabelName first_field_label
+ other_tys = map fieldLabelType other_fields
+
+-------------------------------
+checkValidDataCon :: DataCon -> TcM ()
+checkValidDataCon con
+ = addErrCtxt (dataConCtxt con) (
+ checkValidType ctxt (idType (dataConWrapId con)) `thenM_`
+ -- This checks the argument types and
+ -- ambiguity of the existential context (if any)
+ checkFreeness ex_tvs ex_theta)
+ where
+ ctxt = ConArgCtxt (dataConName con)
+ (_, _, ex_tvs, ex_theta, _, _) = dataConSig con
-Because we can only commit to the final kind of a type variable when
-we've completed the mutually recursive group. For example:
-class C a where
- op :: D b => a -> b -> b
+-------------------------------
+checkValidClass :: Class -> TcM ()
+checkValidClass cls
+ = do { -- CHECK ARITY 1 FOR HASKELL 1.4
+ gla_exts <- doptM Opt_GlasgowExts
-class D c where
- bop :: (Monad c) => ...
-
-Here, the kind of the locally-polymorphic type variable "b"
-depends on *all the uses of class D*. For example, the use of
-Monad c in bop's type signature means that D must have kind Type->Type.
+ -- Check that the class is unary, unless GlaExs
+ ; checkTc (notNull tyvars) (nullaryClassErr cls)
+ ; checkTc (gla_exts || unary) (classArityErr cls)
+ -- Check the super-classes
+ ; checkValidTheta (ClassSCCtxt (className cls)) theta
-\begin{code}
-get_binders :: [RenamedHsDecl]
- -> ([HsTyVar Name], -- TyVars; no dups
- [(Name, Maybe Arity)], -- Tycons; no dups; arities for synonyms
- [(Name, Arity)]) -- Classes; no dups; with their arities
+ -- Check the class operations
+ ; mappM_ check_op op_stuff
-get_binders decls = (bagToList tyvars, bagToList tycons, bagToList classes)
- where
- (tyvars, tycons, classes) = foldr (union3 . get_binders1)
- (emptyBag,emptyBag,emptyBag)
- decls
-
- union3 (a1,a2,a3) (b1,b2,b3)
- = (a1 `unionBags` b1, a2 `unionBags` b2, a3 `unionBags` b3)
-
-get_binders1 (TyD (TySynonym name tyvars _ _))
- = (listToBag tyvars, unitBag (name, Just (length tyvars)), emptyBag)
-get_binders1 (TyD (TyData _ _ name tyvars condecls _ _ _))
- = (listToBag tyvars `unionBags` cons_tvs condecls,
- unitBag (name,Nothing), emptyBag)
-get_binders1 (ClD (ClassDecl _ name tyvars sigs _ _ _ _ _))
- = (listToBag tyvars `unionBags` sigs_tvs sigs,
- emptyBag, unitBag (name, length tyvars))
-
-cons_tvs condecls = unionManyBags (map con_tvs condecls)
+ -- Check that if the class has generic methods, then the
+ -- class has only one parameter. We can't do generic
+ -- multi-parameter type classes!
+ ; checkTc (unary || no_generics) (genericMultiParamErr cls)
+ }
where
- con_tvs (ConDecl _ tvs _ _ _) = listToBag tvs
+ (tyvars, theta, _, op_stuff) = classBigSig cls
+ unary = isSingleton tyvars
+ no_generics = null [() | (_, GenDefMeth) <- op_stuff]
-sigs_tvs sigs = unionManyBags (map sig_tvs sigs)
- where
- sig_tvs (ClassOpSig _ _ ty _) = pty_tvs ty
- pty_tvs (HsForAllTy tvs _ _) = listToBag tvs -- tvs doesn't include the class tyvar
- pty_tvs other = emptyBag
-\end{code}
+ check_op (sel_id, dm)
+ = addErrCtxt (classOpCtxt sel_id) (
+ checkValidTheta SigmaCtxt (tail theta) `thenM_`
+ -- The 'tail' removes the initial (C a) from the
+ -- class itself, leaving just the method type
+
+ checkValidType (FunSigCtxt op_name) tau `thenM_`
+
+ -- Check that for a generic method, the type of
+ -- the method is sufficiently simple
+ checkTc (dm /= GenDefMeth || validGenericMethodType op_ty)
+ (badGenericMethodType op_name op_ty)
+ )
+ where
+ op_name = idName sel_id
+ op_ty = idType sel_id
+ (_,theta,tau) = tcSplitSigmaTy op_ty
-\begin{code}
-typeCycleErr syn_cycles
- = vcat (map (pp_cycle "Cycle in type declarations:") syn_cycles)
-classCycleErr cls_cycles
- = vcat (map (pp_cycle "Cycle in class declarations:") cls_cycles)
+---------------------------------------------------------------------
+fieldTypeMisMatch field_name
+ = sep [ptext SLIT("Different constructors give different types for field"), quotes (ppr field_name)]
-pp_cycle str decls
- = hang (text str)
- 4 (vcat (map pp_decl decls))
+dataConCtxt con = sep [ptext SLIT("When checking the data constructor:"),
+ nest 2 (ex_part <+> pprThetaArrow ex_theta <+> ppr con <+> arg_part)]
where
- pp_decl decl
- = hsep [quotes (ppr name), ptext SLIT("at"), ppr (getSrcLoc name)]
- where
- name = hsDeclName decl
+ (_, _, ex_tvs, ex_theta, arg_tys, _) = dataConSig con
+ ex_part | null ex_tvs = empty
+ | otherwise = ptext SLIT("forall") <+> hsep (map ppr ex_tvs) <> dot
+ -- The 'ex_theta' part could be non-empty, if the user (bogusly) wrote
+ -- data T a = Eq a => T a a
+ -- So we make sure to print it
+
+ fields = dataConFieldLabels con
+ arg_part | null fields = sep (map pprParendType arg_tys)
+ | otherwise = braces (sep (punctuate comma
+ [ ppr n <+> dcolon <+> ppr ty
+ | (n,ty) <- fields `zip` arg_tys]))
+
+classOpCtxt sel_id = sep [ptext SLIT("When checking the class method:"),
+ nest 2 (ppr sel_id <+> dcolon <+> ppr (idType sel_id))]
+
+nullaryClassErr cls
+ = ptext SLIT("No parameters for class") <+> quotes (ppr cls)
+
+classArityErr cls
+ = vcat [ptext SLIT("Too many parameters for class") <+> quotes (ppr cls),
+ parens (ptext SLIT("Use -fglasgow-exts to allow multi-parameter classes"))]
+
+genericMultiParamErr clas
+ = ptext SLIT("The multi-parameter class") <+> quotes (ppr clas) <+>
+ ptext SLIT("cannot have generic methods")
+
+badGenericMethodType op op_ty
+ = hang (ptext SLIT("Generic method type is too complex"))
+ 4 (vcat [ppr op <+> dcolon <+> ppr op_ty,
+ ptext SLIT("You can only use type variables, arrows, and tuples")])
+
+recSynErr tcs
+ = addSrcLoc (getSrcLoc (head tcs)) $
+ addErr (sep [ptext SLIT("Cycle in type synonym declarations:"),
+ nest 2 (vcat (map ppr_thing tcs))])
+
+recClsErr clss
+ = addSrcLoc (getSrcLoc (head clss)) $
+ addErr (sep [ptext SLIT("Cycle in class declarations (via superclasses):"),
+ nest 2 (vcat (map ppr_thing clss))])
+
+ppr_thing :: Name -> SDoc
+ppr_thing n = ppr n <+> parens (ppr (getSrcLoc n))
+
+
+exRecConErr name
+ = ptext SLIT("Can't combine named fields with locally-quantified type variables")
+ $$
+ (ptext SLIT("In the declaration of data constructor") <+> ppr name)
\end{code}