+++ /dev/null
-%
-% (c) The AQUA Project, Glasgow University, 1996-1998
-%
-\section[TcTyClsDecls]{Typecheck type and class declarations}
-
-\begin{code}
-module TcTyClsDecls (
- tcTyAndClassDecls
- ) where
-
-#include "HsVersions.h"
-
-import HsSyn ( TyClDecl(..), HsConDetails(..), HsTyVarBndr(..),
- ConDecl(..), Sig(..), , NewOrData(..), ResType(..),
- tyClDeclTyVars, isSynDecl, hsConArgs,
- LTyClDecl, tcdName, hsTyVarName, LHsTyVarBndr
- )
-import HsTypes ( HsBang(..), getBangStrictness )
-import BasicTypes ( RecFlag(..), StrictnessMark(..) )
-import HscTypes ( implicitTyThings, ModDetails )
-import BuildTyCl ( buildClass, buildAlgTyCon, buildSynTyCon, buildDataCon,
- mkDataTyConRhs, mkNewTyConRhs )
-import TcRnMonad
-import TcEnv ( TyThing(..),
- tcLookupLocated, tcLookupLocatedGlobal,
- tcExtendGlobalEnv, tcExtendKindEnv, tcExtendKindEnvTvs,
- tcExtendRecEnv, tcLookupTyVar )
-import TcTyDecls ( calcTyConArgVrcs, calcRecFlags, calcClassCycles, calcSynCycles )
-import TcClassDcl ( tcClassSigs, tcAddDeclCtxt )
-import TcHsType ( kcHsTyVars, kcHsLiftedSigType, kcHsType,
- kcHsContext, tcTyVarBndrs, tcHsKindedType, tcHsKindedContext,
- kcHsSigType, tcHsBangType, tcLHsConResTy, tcDataKindSig )
-import TcMType ( newKindVar, checkValidTheta, checkValidType,
- -- checkFreeness,
- UserTypeCtxt(..), SourceTyCtxt(..) )
-import TcType ( TcKind, TcType, tyVarsOfType, mkPhiTy,
- mkArrowKind, liftedTypeKind, mkTyVarTys,
- tcSplitSigmaTy, tcEqTypes, tcGetTyVar_maybe )
-import Type ( splitTyConApp_maybe,
- -- pprParendType, pprThetaArrow
- )
-import Kind ( mkArrowKinds, splitKindFunTys )
-import Generics ( validGenericMethodType, canDoGenerics )
-import Class ( Class, className, classTyCon, DefMeth(..), classBigSig, classTyVars )
-import TyCon ( TyCon, ArgVrcs, AlgTyConRhs( AbstractTyCon ),
- tyConDataCons, mkForeignTyCon, isProductTyCon, isRecursiveTyCon,
- tyConStupidTheta, synTyConRhs, isSynTyCon, tyConName )
-import DataCon ( DataCon, dataConWrapId, dataConName,
- dataConFieldLabels, dataConTyCon,
- dataConTyVars, dataConFieldType, dataConResTys )
-import Var ( TyVar, idType, idName )
-import VarSet ( elemVarSet, mkVarSet )
-import Name ( Name, getSrcLoc )
-import Outputable
-import Maybe ( isJust )
-import Maybes ( expectJust )
-import Unify ( tcMatchTys, tcMatchTyX )
-import Util ( zipLazy, isSingleton, notNull, sortLe )
-import List ( partition )
-import SrcLoc ( Located(..), unLoc, getLoc, srcLocSpan )
-import ListSetOps ( equivClasses )
-import List ( delete )
-import Digraph ( SCC(..) )
-import DynFlags ( DynFlag( Opt_GlasgowExts, Opt_Generics,
- Opt_UnboxStrictFields ) )
-\end{code}
-
-
-%************************************************************************
-%* *
-\subsection{Type checking for type and class declarations}
-%* *
-%************************************************************************
-
-Dealing with a group
-~~~~~~~~~~~~~~~~~~~~
-Consider a mutually-recursive group, binding
-a type constructor T and a class C.
-
-Step 1: getInitialKind
- Construct a KindEnv by binding T and C to a kind variable
-
-Step 2: kcTyClDecl
- In that environment, do a kind check
-
-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
-
-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.
-
-
-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
-
-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.
-
-
-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.
-
-\begin{code}
-tcTyAndClassDecls :: ModDetails -> [LTyClDecl Name]
- -> TcM TcGblEnv -- Input env extended by types and classes
- -- and their implicit Ids,DataCons
-tcTyAndClassDecls boot_details decls
- = do { -- First check for cyclic type synonysm or classes
- -- See notes with checkCycleErrs
- checkCycleErrs decls
- ; mod <- getModule
- ; traceTc (text "tcTyAndCl" <+> ppr mod)
- ; (syn_tycons, alg_tyclss) <- fixM (\ ~(rec_syn_tycons, rec_alg_tyclss) ->
- do { let { -- Calculate variances and rec-flag
- ; (syn_decls, alg_decls) = partition (isSynDecl . unLoc) decls }
-
- -- Extend the global env with the knot-tied results
- -- for data types and classes
- --
- -- 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
- ; let { gbl_things = mkGlobalThings alg_decls rec_alg_tyclss }
- ; tcExtendRecEnv gbl_things $ do
-
- -- Kind-check the declarations
- { (kc_syn_decls, kc_alg_decls) <- kcTyClDecls syn_decls alg_decls
-
- ; let { calc_vrcs = calcTyConArgVrcs (rec_syn_tycons ++ rec_alg_tyclss)
- ; calc_rec = calcRecFlags boot_details rec_alg_tyclss
- ; tc_decl = addLocM (tcTyClDecl calc_vrcs calc_rec) }
- -- Type-check the type synonyms, and extend the envt
- ; syn_tycons <- tcSynDecls calc_vrcs kc_syn_decls
- ; tcExtendGlobalEnv syn_tycons $ do
-
- -- Type-check the data types and classes
- { alg_tyclss <- mappM tc_decl kc_alg_decls
- ; return (syn_tycons, alg_tyclss)
- }}})
- -- Finished with knot-tying now
- -- Extend the environment with the finished things
- ; tcExtendGlobalEnv (syn_tycons ++ alg_tyclss) $ do
-
- -- Perform the validity check
- { traceTc (text "ready for validity check")
- ; mappM_ (addLocM 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 alg_tyclss }
- ; traceTc ((text "Adding" <+> ppr alg_tyclss) $$ (text "and" <+> ppr implicit_things))
- ; tcExtendGlobalEnv implicit_things getGblEnv
- }}
-
-mkGlobalThings :: [LTyClDecl Name] -- 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
- mk_thing (L _ (ClassDecl {tcdLName = L _ name}), ~(AClass cl))
- = (name, AClass cl)
- mk_thing (L _ decl, ~(ATyCon tc))
- = (tcdName decl, ATyCon tc)
-\end{code}
-
-
-%************************************************************************
-%* *
- Kind checking
-%* *
-%************************************************************************
-
-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
-
-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.
-
-However type synonyms work differently. They can have kinds which don't
-just involve (->) and *:
- type R = Int# -- Kind #
- type S a = Array# a -- Kind * -> #
- type T a b = (# a,b #) -- Kind * -> * -> (# a,b #)
-So we must infer their kinds from their right-hand sides *first* and then
-use them, whereas for the mutually recursive data types D we bring into
-scope kind bindings D -> k, where k is a kind variable, and do inference.
-
-\begin{code}
-kcTyClDecls syn_decls alg_decls
- = do { -- First extend the kind env with each data
- -- type and class, mapping them to a type variable
- alg_kinds <- mappM getInitialKind alg_decls
- ; tcExtendKindEnv alg_kinds $ do
-
- -- Now kind-check the type synonyms, in dependency order
- -- We do these differently to data type and classes,
- -- because a type synonym can be an unboxed type
- -- type Foo = Int#
- -- and a kind variable can't unify with UnboxedTypeKind
- -- So we infer their kinds in dependency order
- { (kc_syn_decls, syn_kinds) <- kcSynDecls (calcSynCycles syn_decls)
- ; tcExtendKindEnv syn_kinds $ do
-
- -- Now kind-check the data type and class declarations,
- -- returning kind-annotated decls
- { kc_alg_decls <- mappM (wrapLocM kcTyClDecl) alg_decls
-
- ; return (kc_syn_decls, kc_alg_decls) }}}
-
-------------------------------------------------------------------------
-getInitialKind :: LTyClDecl Name -> TcM (Name, TcKind)
--- Only for data type and class declarations
--- Get as much info as possible from the data or class decl,
--- so as to maximise usefulness of error messages
-getInitialKind (L _ decl)
- = do { arg_kinds <- mapM (mk_arg_kind . unLoc) (tyClDeclTyVars decl)
- ; res_kind <- mk_res_kind decl
- ; return (tcdName decl, mkArrowKinds arg_kinds res_kind) }
- where
- mk_arg_kind (UserTyVar _) = newKindVar
- mk_arg_kind (KindedTyVar _ kind) = return kind
-
- mk_res_kind (TyData { tcdKindSig = Just kind }) = return kind
- -- On GADT-style declarations we allow a kind signature
- -- data T :: *->* where { ... }
- mk_res_kind other = return liftedTypeKind
-
-
-----------------
-kcSynDecls :: [SCC (LTyClDecl Name)]
- -> TcM ([LTyClDecl Name], -- Kind-annotated decls
- [(Name,TcKind)]) -- Kind bindings
-kcSynDecls []
- = return ([], [])
-kcSynDecls (group : groups)
- = do { (decl, nk) <- kcSynDecl group
- ; (decls, nks) <- tcExtendKindEnv [nk] (kcSynDecls groups)
- ; return (decl:decls, nk:nks) }
-
-----------------
-kcSynDecl :: SCC (LTyClDecl Name)
- -> TcM (LTyClDecl Name, -- Kind-annotated decls
- (Name,TcKind)) -- Kind bindings
-kcSynDecl (AcyclicSCC ldecl@(L loc decl))
- = tcAddDeclCtxt decl $
- kcHsTyVars (tcdTyVars decl) (\ k_tvs ->
- do { traceTc (text "kcd1" <+> ppr (unLoc (tcdLName decl)) <+> brackets (ppr (tcdTyVars decl))
- <+> brackets (ppr k_tvs))
- ; (k_rhs, rhs_kind) <- kcHsType (tcdSynRhs decl)
- ; traceTc (text "kcd2" <+> ppr (unLoc (tcdLName decl)))
- ; let tc_kind = foldr (mkArrowKind . kindedTyVarKind) rhs_kind k_tvs
- ; return (L loc (decl { tcdTyVars = k_tvs, tcdSynRhs = k_rhs }),
- (unLoc (tcdLName decl), tc_kind)) })
-
-kcSynDecl (CyclicSCC decls)
- = do { recSynErr decls; failM } -- Fail here to avoid error cascade
- -- of out-of-scope tycons
-
-kindedTyVarKind (L _ (KindedTyVar _ k)) = k
-
-------------------------------------------------------------------------
-kcTyClDecl :: TyClDecl Name -> TcM (TyClDecl Name)
- -- Not used for type synonyms (see kcSynDecl)
-
-kcTyClDecl decl@(TyData {tcdND = new_or_data, tcdCtxt = ctxt, tcdCons = cons})
- = kcTyClDeclBody decl $ \ tvs' ->
- do { ctxt' <- kcHsContext ctxt
- ; cons' <- mappM (wrapLocM kc_con_decl) cons
- ; return (decl {tcdTyVars = tvs', tcdCtxt = ctxt', tcdCons = cons'}) }
- where
- kc_con_decl (ConDecl name expl ex_tvs ex_ctxt details res) = do
- kcHsTyVars ex_tvs $ \ex_tvs' -> do
- ex_ctxt' <- kcHsContext ex_ctxt
- details' <- kc_con_details details
- res' <- case res of
- ResTyH98 -> return ResTyH98
- ResTyGADT ty -> return . ResTyGADT =<< kcHsSigType ty
- return (ConDecl name expl ex_tvs' ex_ctxt' details' res')
-
- kc_con_details (PrefixCon btys)
- = do { btys' <- mappM kc_larg_ty btys ; return (PrefixCon btys') }
- kc_con_details (InfixCon bty1 bty2)
- = do { bty1' <- kc_larg_ty bty1; bty2' <- kc_larg_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_larg_ty bty ; return (fld, bty') }
-
- kc_larg_ty bty = case new_or_data of
- DataType -> kcHsSigType bty
- NewType -> kcHsLiftedSigType bty
- -- Can't allow an unlifted type for newtypes, because we're effectively
- -- going to remove the constructor while coercing it to a lifted type.
- -- And newtypes can't be bang'd
-
-kcTyClDecl decl@(ClassDecl {tcdCtxt = ctxt, tcdSigs = sigs})
- = kcTyClDeclBody decl $ \ tvs' ->
- do { is_boot <- tcIsHsBoot
- ; checkTc (not is_boot) badBootClassDeclErr
- ; ctxt' <- kcHsContext ctxt
- ; sigs' <- mappM (wrapLocM kc_sig) sigs
- ; return (decl {tcdTyVars = tvs', tcdCtxt = ctxt', tcdSigs = sigs'}) }
- where
- kc_sig (TypeSig nm op_ty) = do { op_ty' <- kcHsLiftedSigType op_ty
- ; return (TypeSig nm op_ty') }
- kc_sig other_sig = return other_sig
-
-kcTyClDecl decl@(ForeignType {})
- = return decl
-
-kcTyClDeclBody :: TyClDecl Name
- -> ([LHsTyVarBndr Name] -> TcM a)
- -> TcM a
--- getInitialKind has made a suitably-shaped kind for the type or class
--- Unpack it, and attribute those kinds to the type variables
--- 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 thing_inside
- = tcAddDeclCtxt decl $
- do { tc_ty_thing <- tcLookupLocated (tcdLName decl)
- ; let tc_kind = case tc_ty_thing of { AThing k -> k }
- (kinds, _) = splitKindFunTys tc_kind
- hs_tvs = tcdTyVars decl
- kinded_tvs = ASSERT( length kinds >= length hs_tvs )
- [ L loc (KindedTyVar (hsTyVarName tv) k)
- | (L loc tv, k) <- zip hs_tvs kinds]
- ; tcExtendKindEnvTvs kinded_tvs (thing_inside kinded_tvs) }
-\end{code}
-
-
-%************************************************************************
-%* *
-\subsection{Type checking}
-%* *
-%************************************************************************
-
-\begin{code}
-tcSynDecls :: (Name -> ArgVrcs) -> [LTyClDecl Name] -> TcM [TyThing]
-tcSynDecls calc_vrcs [] = return []
-tcSynDecls calc_vrcs (decl : decls)
- = do { syn_tc <- addLocM (tcSynDecl calc_vrcs) decl
- ; syn_tcs <- tcExtendGlobalEnv [syn_tc] (tcSynDecls calc_vrcs decls)
- ; return (syn_tc : syn_tcs) }
-
-tcSynDecl calc_vrcs
- (TySynonym {tcdLName = L _ tc_name, tcdTyVars = tvs, tcdSynRhs = rhs_ty})
- = tcTyVarBndrs tvs $ \ tvs' -> do
- { traceTc (text "tcd1" <+> ppr tc_name)
- ; rhs_ty' <- tcHsKindedType rhs_ty
- ; return (ATyCon (buildSynTyCon tc_name tvs' rhs_ty' (calc_vrcs tc_name))) }
-
---------------------
-tcTyClDecl :: (Name -> ArgVrcs) -> (Name -> RecFlag)
- -> TyClDecl Name -> TcM TyThing
-
-tcTyClDecl calc_vrcs calc_isrec decl
- = tcAddDeclCtxt decl (tcTyClDecl1 calc_vrcs calc_isrec decl)
-
-tcTyClDecl1 calc_vrcs calc_isrec
- (TyData {tcdND = new_or_data, tcdCtxt = ctxt, tcdTyVars = tvs,
- tcdLName = L _ tc_name, tcdKindSig = mb_ksig, tcdCons = cons})
- = tcTyVarBndrs tvs $ \ tvs' -> do
- { extra_tvs <- tcDataKindSig mb_ksig
- ; let final_tvs = tvs' ++ extra_tvs
- ; stupid_theta <- tcHsKindedContext ctxt
- ; want_generic <- doptM Opt_Generics
- ; unbox_strict <- doptM Opt_UnboxStrictFields
- ; gla_exts <- doptM Opt_GlasgowExts
- ; is_boot <- tcIsHsBoot -- Are we compiling an hs-boot file?
-
- -- Check that we don't use GADT syntax in H98 world
- ; checkTc (gla_exts || h98_syntax) (badGadtDecl tc_name)
-
- -- Check that there's at least one condecl,
- -- or else we're reading an interface file, or -fglasgow-exts
- ; checkTc (not (null cons) || gla_exts || is_boot)
- (emptyConDeclsErr tc_name)
-
- -- Check that a newtype has exactly one constructor
- ; checkTc (new_or_data == DataType || isSingleton cons)
- (newtypeConError tc_name (length cons))
-
- ; tycon <- fixM (\ tycon -> do
- { data_cons <- mappM (addLocM (tcConDecl unbox_strict new_or_data
- tycon final_tvs))
- cons
- ; let tc_rhs
- | null cons && is_boot -- In a hs-boot file, empty cons means
- = AbstractTyCon -- "don't know"; hence Abstract
- | otherwise
- = case new_or_data of
- DataType -> mkDataTyConRhs data_cons
- NewType -> ASSERT( isSingleton data_cons )
- mkNewTyConRhs tycon (head data_cons)
- ; buildAlgTyCon tc_name final_tvs stupid_theta tc_rhs arg_vrcs is_rec
- (want_generic && canDoGenerics data_cons)
- })
- ; return (ATyCon tycon)
- }
- where
- arg_vrcs = calc_vrcs tc_name
- is_rec = calc_isrec tc_name
- h98_syntax = case cons of -- All constructors have same shape
- L _ (ConDecl { con_res = ResTyGADT _ }) : _ -> False
- other -> True
-
-tcTyClDecl1 calc_vrcs calc_isrec
- (ClassDecl {tcdLName = L _ class_name, tcdTyVars = tvs,
- tcdCtxt = ctxt, tcdMeths = meths,
- tcdFDs = fundeps, tcdSigs = sigs} )
- = tcTyVarBndrs tvs $ \ tvs' -> do
- { ctxt' <- tcHsKindedContext ctxt
- ; fds' <- mappM (addLocM 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 {tcdLName = L _ tc_name, tcdExtName = tc_ext_name})
- = returnM (ATyCon (mkForeignTyCon tc_name tc_ext_name liftedTypeKind 0 []))
-
------------------------------------
-tcConDecl :: Bool -- True <=> -funbox-strict_fields
- -> NewOrData -> TyCon -> [TyVar]
- -> ConDecl Name -> TcM DataCon
-
-tcConDecl unbox_strict NewType tycon tc_tvs -- Newtypes
- (ConDecl name _ ex_tvs ex_ctxt details ResTyH98)
- = do { let tc_datacon field_lbls arg_ty
- = do { arg_ty' <- tcHsKindedType arg_ty -- No bang on newtype
- ; buildDataCon (unLoc name) False {- Prefix -}
- True {- Vanilla -} [NotMarkedStrict]
- (map unLoc field_lbls)
- tc_tvs [] [arg_ty']
- tycon (mkTyVarTys tc_tvs) }
-
- -- Check that a newtype has no existential stuff
- ; checkTc (null ex_tvs && null (unLoc ex_ctxt)) (newtypeExError name)
-
- ; case details of
- PrefixCon [arg_ty] -> tc_datacon [] arg_ty
- RecCon [(field_lbl, arg_ty)] -> tc_datacon [field_lbl] arg_ty
- other -> failWithTc (newtypeFieldErr name (length (hsConArgs details)))
- -- Check that the constructor has exactly one field
- }
-
-tcConDecl unbox_strict DataType tycon tc_tvs -- Data types
- (ConDecl name _ tvs ctxt details res_ty)
- = tcTyVarBndrs tvs $ \ tvs' -> do
- { ctxt' <- tcHsKindedContext ctxt
- ; (data_tc, res_ty_args) <- tcResultType tycon tc_tvs res_ty
- ; let
- con_tvs = case res_ty of
- ResTyH98 -> tc_tvs ++ tvs'
- ResTyGADT _ -> tryVanilla tvs' res_ty_args
-
- -- Vanilla iff result type matches the quantified vars exactly,
- -- and there is no existential context
- -- Must check the context too because of implicit params; e.g.
- -- data T = (?x::Int) => MkT Int
- is_vanilla = res_ty_args `tcEqTypes` mkTyVarTys con_tvs
- && null (unLoc ctxt)
-
- tc_datacon is_infix field_lbls btys
- = do { let bangs = map getBangStrictness btys
- ; arg_tys <- mappM tcHsBangType btys
- ; buildDataCon (unLoc name) is_infix is_vanilla
- (argStrictness unbox_strict tycon bangs arg_tys)
- (map unLoc field_lbls)
- con_tvs ctxt' arg_tys
- data_tc res_ty_args }
- -- NB: we put data_tc, the type constructor gotten from the constructor
- -- type signature into the data constructor; that way
- -- checkValidDataCon can complain if it's wrong.
-
- ; case details of
- PrefixCon btys -> tc_datacon False [] btys
- InfixCon bty1 bty2 -> tc_datacon True [] [bty1,bty2]
- RecCon fields -> tc_datacon False field_names btys
- where
- (field_names, btys) = unzip fields
-
- }
-
-tcResultType :: TyCon -> [TyVar] -> ResType Name -> TcM (TyCon, [TcType])
-tcResultType tycon tvs ResTyH98 = return (tycon, mkTyVarTys tvs)
-tcResultType _ _ (ResTyGADT res_ty) = tcLHsConResTy res_ty
-
-tryVanilla :: [TyVar] -> [TcType] -> [TyVar]
--- (tryVanilla tvs tys) returns a permutation of tvs.
--- It tries to re-order the tvs so that it exactly
--- matches the [Type], if that is possible
-tryVanilla tvs (ty:tys) | Just tv <- tcGetTyVar_maybe ty -- The type is a tyvar
- , tv `elem` tvs -- That tyvar is in the list
- = tv : tryVanilla (delete tv tvs) tys
-tryVanilla tvs tys = tvs -- Fall through case
-
-
--------------------
-argStrictness :: Bool -- True <=> -funbox-strict_fields
- -> TyCon -> [HsBang]
- -> [TcType] -> [StrictnessMark]
-argStrictness unbox_strict tycon bangs arg_tys
- = ASSERT( length bangs == length arg_tys )
- zipWith (chooseBoxingStrategy unbox_strict tycon) arg_tys bangs
-
--- 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}
-%* *
-%************************************************************************
-
-Validity checking is done once the mutually-recursive knot has been
-tied, so we can look at things freely.
-
-\begin{code}
-checkCycleErrs :: [LTyClDecl Name] -> TcM ()
-checkCycleErrs tyclss
- | null cls_cycles
- = return ()
- | otherwise
- = do { mappM_ recClsErr cls_cycles
- ; failM } -- Give up now, because later checkValidTyCl
- -- will loop if the synonym is recursive
- where
- cls_cycles = calcClassCycles tyclss
-
-checkValidTyCl :: TyClDecl Name -> 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 <- tcLookupLocatedGlobal (tcdLName 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)
- }
-
--------------------------
--- For data types declared with record syntax, we require
--- that each constructor that has a field 'f'
--- (a) has the same result type
--- (b) has the same type for 'f'
--- module alpha conversion of the quantified type variables
--- of the constructor.
-
-checkValidTyCon :: TyCon -> TcM ()
-checkValidTyCon tc
- | isSynTyCon tc
- = checkValidType syn_ctxt syn_rhs
- | otherwise
- = -- Check the context on the data decl
- checkValidTheta (DataTyCtxt name) (tyConStupidTheta tc) `thenM_`
-
- -- Check arg types of data constructors
- mappM_ (checkValidDataCon tc) data_cons `thenM_`
-
- -- Check that fields with the same name share a type
- mappM_ check_fields groups
-
- where
- syn_ctxt = TySynCtxt name
- name = tyConName tc
- syn_rhs = synTyConRhs tc
- data_cons = tyConDataCons tc
-
- groups = equivClasses cmp_fld (concatMap get_fields data_cons)
- cmp_fld (f1,_) (f2,_) = f1 `compare` f2
- get_fields con = dataConFieldLabels con `zip` repeat con
- -- dataConFieldLabels may return the empty list, which is fine
-
- -- XXX - autrijus - Make this far more complex to acommodate
- -- for different return types. Add res_ty to the mix,
- -- comparing them in two steps, all for good error messages.
- -- Plan: Use Unify.tcMatchTys to compare the first candidate's
- -- result type against other candidates' types (check bothways).
- -- If they magically agrees, take the substitution and
- -- apply them to the latter ones, and see if they match perfectly.
- -- check_fields fields@((first_field_label, field_ty) : other_fields)
- check_fields fields@((label, con1) : other_fields)
- -- These fields all have the same name, but are from
- -- different constructors in the data type
- = recoverM (return ()) $ mapM_ checkOne other_fields
- -- 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
- where
- tvs1 = mkVarSet (dataConTyVars con1)
- res1 = dataConResTys con1
- fty1 = dataConFieldType con1 label
-
- checkOne (_, con2) -- Do it bothways to ensure they are structurally identical
- = do { checkFieldCompat label con1 con2 tvs1 res1 res2 fty1 fty2
- ; checkFieldCompat label con2 con1 tvs2 res2 res1 fty2 fty1 }
- where
- tvs2 = mkVarSet (dataConTyVars con2)
- res2 = dataConResTys con2
- fty2 = dataConFieldType con2 label
-
-checkFieldCompat fld con1 con2 tvs1 res1 res2 fty1 fty2
- = do { checkTc (isJust mb_subst1) (resultTypeMisMatch fld con1 con2)
- ; checkTc (isJust mb_subst2) (fieldTypeMisMatch fld con1 con2) }
- where
- mb_subst1 = tcMatchTys tvs1 res1 res2
- mb_subst2 = tcMatchTyX tvs1 (expectJust "checkFieldCompat" mb_subst1) fty1 fty2
-
--------------------------------
-checkValidDataCon :: TyCon -> DataCon -> TcM ()
-checkValidDataCon tc con
- = setSrcSpan (srcLocSpan (getSrcLoc con)) $
- addErrCtxt (dataConCtxt con) $
- do { checkTc (dataConTyCon con == tc) (badDataConTyCon con)
- ; checkValidType ctxt (idType (dataConWrapId con)) }
-
- -- This checks the argument types and
- -- ambiguity of the existential context (if any)
- --
- -- Note [Sept 04] Now that tvs is all the tvs, this
- -- test doesn't actually check anything
--- ; checkFreeness tvs ex_theta }
- where
- ctxt = ConArgCtxt (dataConName con)
--- (tvs, ex_theta, _, _, _) = dataConSig con
-
-
--------------------------------
-checkValidClass :: Class -> TcM ()
-checkValidClass cls
- = do { -- CHECK ARITY 1 FOR HASKELL 1.4
- gla_exts <- doptM Opt_GlasgowExts
-
- -- 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
-
- -- Check the class operations
- ; mappM_ (check_op gla_exts) op_stuff
-
- -- 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
- (tyvars, theta, _, op_stuff) = classBigSig cls
- unary = isSingleton tyvars
- no_generics = null [() | (_, GenDefMeth) <- op_stuff]
-
- check_op gla_exts (sel_id, dm)
- = addErrCtxt (classOpCtxt sel_id tau) $ do
- { checkValidTheta SigmaCtxt (tail theta)
- -- The 'tail' removes the initial (C a) from the
- -- class itself, leaving just the method type
-
- ; checkValidType (FunSigCtxt op_name) tau
-
- -- Check that the type mentions at least one of
- -- the class type variables
- ; checkTc (any (`elemVarSet` tyVarsOfType tau) tyvars)
- (noClassTyVarErr cls sel_id)
-
- -- Check that for a generic method, the type of
- -- the method is sufficiently simple
- ; checkTc (dm /= GenDefMeth || validGenericMethodType tau)
- (badGenericMethodType op_name op_ty)
- }
- where
- op_name = idName sel_id
- op_ty = idType sel_id
- (_,theta1,tau1) = tcSplitSigmaTy op_ty
- (_,theta2,tau2) = tcSplitSigmaTy tau1
- (theta,tau) | gla_exts = (theta1 ++ theta2, tau2)
- | otherwise = (theta1, mkPhiTy (tail theta1) tau1)
- -- Ugh! The function might have a type like
- -- op :: forall a. C a => forall b. (Eq b, Eq a) => tau2
- -- With -fglasgow-exts, we want to allow this, even though the inner
- -- forall has an (Eq a) constraint. Whereas in general, each constraint
- -- in the context of a for-all must mention at least one quantified
- -- type variable. What a mess!
-
-
----------------------------------------------------------------------
-resultTypeMisMatch field_name con1 con2
- = vcat [sep [ptext SLIT("Constructors") <+> ppr con1 <+> ptext SLIT("and") <+> ppr con2,
- ptext SLIT("have a common field") <+> quotes (ppr field_name) <> comma],
- nest 2 $ ptext SLIT("but have different result types")]
-fieldTypeMisMatch field_name con1 con2
- = sep [ptext SLIT("Constructors") <+> ppr con1 <+> ptext SLIT("and") <+> ppr con2,
- ptext SLIT("give different types for field"), quotes (ppr field_name)]
-
-dataConCtxt con = ptext SLIT("In the definition of data constructor") <+> quotes (ppr con)
-
-classOpCtxt sel_id tau = sep [ptext SLIT("When checking the class method:"),
- nest 2 (ppr sel_id <+> dcolon <+> ppr tau)]
-
-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"))]
-
-noClassTyVarErr clas op
- = sep [ptext SLIT("The class method") <+> quotes (ppr op),
- ptext SLIT("mentions none of the type variables of the class") <+>
- ppr clas <+> hsep (map ppr (classTyVars clas))]
-
-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, lists, and tuples")])
-
-recSynErr syn_decls
- = setSrcSpan (getLoc (head sorted_decls)) $
- addErr (sep [ptext SLIT("Cycle in type synonym declarations:"),
- nest 2 (vcat (map ppr_decl sorted_decls))])
- where
- sorted_decls = sortLocated syn_decls
- ppr_decl (L loc decl) = ppr loc <> colon <+> ppr decl
-
-recClsErr cls_decls
- = setSrcSpan (getLoc (head sorted_decls)) $
- addErr (sep [ptext SLIT("Cycle in class declarations (via superclasses):"),
- nest 2 (vcat (map ppr_decl sorted_decls))])
- where
- sorted_decls = sortLocated cls_decls
- ppr_decl (L loc decl) = ppr loc <> colon <+> ppr (decl { tcdSigs = [] })
-
-sortLocated :: [Located a] -> [Located a]
-sortLocated things = sortLe le things
- where
- le (L l1 _) (L l2 _) = l1 <= l2
-
-badDataConTyCon data_con
- = hang (ptext SLIT("Data constructor") <+> quotes (ppr data_con) <+>
- ptext SLIT("returns type") <+> quotes (ppr (dataConTyCon data_con)))
- 2 (ptext SLIT("instead of its parent type"))
-
-badGadtDecl tc_name
- = vcat [ ptext SLIT("Illegal generalised algebraic data declaration for") <+> quotes (ppr tc_name)
- , nest 2 (parens $ ptext SLIT("Use -fglasgow-exts to allow GADTs")) ]
-
-newtypeConError tycon n
- = sep [ptext SLIT("A newtype must have exactly one constructor,"),
- nest 2 $ ptext SLIT("but") <+> quotes (ppr tycon) <+> ptext SLIT("has") <+> speakN n ]
-
-newtypeExError con
- = sep [ptext SLIT("A newtype constructor cannot have an existential context,"),
- nest 2 $ ptext SLIT("but") <+> quotes (ppr con) <+> ptext SLIT("does")]
-
-newtypeFieldErr con_name n_flds
- = sep [ptext SLIT("The constructor of a newtype must have exactly one field"),
- nest 2 $ ptext SLIT("but") <+> quotes (ppr con_name) <+> ptext SLIT("has") <+> speakN n_flds]
-
-emptyConDeclsErr tycon
- = sep [quotes (ppr tycon) <+> ptext SLIT("has no constructors"),
- nest 2 $ ptext SLIT("(-fglasgow-exts permits this)")]
-
-badBootClassDeclErr = ptext SLIT("Illegal class declaration in hs-boot file")
-\end{code}
projects / ghc-hetmet.git / blobdiff