\begin{code}
module TcType (
- TcTyVar, TcBox,
+ TcTyVar,
TcTyVarSet,
- newTcTyVar,
- newTyVarTy, -- Kind -> NF_TcM s (TcType s)
- newTyVarTys, -- Int -> Kind -> NF_TcM s [TcType s]
+ newTyVar,
+ newTyVarTy, -- Kind -> NF_TcM TcType
+ newTyVarTys, -- Int -> Kind -> NF_TcM [TcType]
-----------------------------------------
- TcType, TcMaybe(..),
- TcTauType, TcThetaType, TcRhoType,
+ TcType, TcTauType, TcThetaType, TcRhoType,
-- Find the type to which a type variable is bound
- tcWriteTyVar, -- :: TcTyVar s -> TcType s -> NF_TcM (TcType s)
- tcReadTyVar, -- :: TcTyVar s -> NF_TcM (TcMaybe s)
+ tcPutTyVar, -- :: TcTyVar -> TcType -> NF_TcM TcType
+ tcGetTyVar, -- :: TcTyVar -> NF_TcM (Maybe TcType) does shorting out
tcSplitRhoTy,
- tcInstTyVars,
- tcInstTcType,
-
- typeToTcType,
+ tcInstTyVar, tcInstTyVars,
+ tcInstSigVars,
+ tcInstType,
--------------------------------
TcKind,
- newKindVar, newKindVars,
- kindToTcKind,
- zonkTcKind,
+ newKindVar, newKindVars, newBoxityVar,
--------------------------------
- zonkTcTyVar, zonkTcTyVars, zonkTcTyVarBndr,
- zonkTcType, zonkTcTypes, zonkTcThetaType,
+ zonkTcTyVar, zonkTcTyVars, zonkTcTyVarsAndFV, zonkTcSigTyVars,
+ zonkTcType, zonkTcTypes, zonkTcClassConstraints, zonkTcThetaType,
+ zonkTcPredType,
- zonkTcTypeToType, zonkTcTyVarToTyVar,
- zonkTcKindToKind
+ zonkTcTypeToType, zonkTcTyVarToTyVar, zonkKindEnv
) where
-- friends:
-import PprType ()
-import Type ( Type, Kind, ThetaType, GenType(..), TyNote(..),
- mkAppTy,
- splitDictTy_maybe, splitForAllTys,
- isTyVarTy, mkTyVarTys,
- fullSubstTy, substFlexiTy,
- boxedTypeKind, superKind
- )
-import VarEnv
-import VarSet ( emptyVarSet )
-import Var ( TyVar, GenTyVar, tyVarKind, tyVarFlexi, tyVarName,
- mkFlexiTyVar, removeTyVarFlexi, isFlexiTyVar, isTyVar
+import TypeRep ( Type(..), Kind, TyNote(..) ) -- friend
+import Type ( PredType(..),
+ getTyVar, mkAppTy, mkUTy,
+ splitPredTy_maybe, splitForAllTys,
+ isTyVarTy, mkTyVarTy, mkTyVarTys,
+ openTypeKind, liftedTypeKind,
+ superKind, superBoxity, tyVarsOfTypes,
+ defaultKind, liftedBoxity
)
+import Subst ( Subst, mkTopTyVarSubst, substTy )
+import TyCon ( mkPrimTyCon )
+import PrimRep ( PrimRep(VoidRep) )
+import Var ( TyVar, tyVarKind, tyVarName, isTyVar, isMutTyVar, mkTyVar )
-- others:
-import TcMonad
-import Name ( changeUnique )
-
+import TcMonad -- TcType, amongst others
import TysWiredIn ( voidTy )
-import Name ( NamedThing(..), changeUnique, mkSysLocalName )
-import Unique ( Unique )
+import Name ( Name, NamedThing(..), setNameUnique, mkSysLocalName,
+ mkLocalName, mkDerivedTyConOcc
+ )
+import Unique ( Uniquable(..) )
+import SrcLoc ( noSrcLoc )
import Util ( nOfThem )
import Outputable
\end{code}
-
-Data types
-~~~~~~~~~~
-See TcMonad.lhs
-
-\begin{code}
-tcTyVarToTyVar :: TcTyVar s -> TyVar
-tcTyVarToTyVar = removeTyVarFlexi
-\end{code}
-
Utility functions
~~~~~~~~~~~~~~~~~
These tcSplit functions are like their non-Tc analogues, but they
to a for-all type.
\begin{code}
-tcSplitRhoTy :: TcType s -> NF_TcM s (TcThetaType s, TcType s)
+tcSplitRhoTy :: TcType -> NF_TcM (TcThetaType, TcType)
tcSplitRhoTy t
= go t t []
where
-- A type variable is never instantiated to a dictionary type,
-- so we don't need to do a tcReadVar on the "arg".
- go syn_t (FunTy arg res) ts = case splitDictTy_maybe arg of
+ go syn_t (FunTy arg res) ts = case splitPredTy_maybe arg of
Just pair -> go res res (pair:ts)
Nothing -> returnNF_Tc (reverse ts, syn_t)
go syn_t (NoteTy _ t) ts = go syn_t t ts
- go syn_t (TyVarTy tv) ts = tcReadTyVar tv `thenNF_Tc` \ maybe_ty ->
+ go syn_t (TyVarTy tv) ts = tcGetTyVar tv `thenNF_Tc` \ maybe_ty ->
case maybe_ty of
- BoundTo ty | not (isTyVarTy ty) -> go syn_t ty ts
- other -> returnNF_Tc (reverse ts, syn_t)
+ Just ty | not (isTyVarTy ty) -> go syn_t ty ts
+ other -> returnNF_Tc (reverse ts, syn_t)
+ go syn_t (UsageTy _ t) ts = go syn_t t ts
go syn_t t ts = returnNF_Tc (reverse ts, syn_t)
\end{code}
-New type variables
-~~~~~~~~~~~~~~~~~~
+%************************************************************************
+%* *
+\subsection{New type variables}
+%* *
+%************************************************************************
\begin{code}
-newTcTyVar :: Kind -> NF_TcM s (TcTyVar s)
-newTcTyVar kind
+newTyVar :: Kind -> NF_TcM TcTyVar
+newTyVar kind
= tcGetUnique `thenNF_Tc` \ uniq ->
- tcNewMutVar UnBound `thenNF_Tc` \ box ->
- let
- name = mkSysLocalName uniq
- in
- returnNF_Tc (mkFlexiTyVar name kind box)
+ tcNewMutTyVar (mkSysLocalName uniq SLIT("t")) kind
-newTyVarTy :: Kind -> NF_TcM s (TcType s)
+newTyVarTy :: Kind -> NF_TcM TcType
newTyVarTy kind
- = newTcTyVar kind `thenNF_Tc` \ tc_tyvar ->
+ = newTyVar kind `thenNF_Tc` \ tc_tyvar ->
returnNF_Tc (TyVarTy tc_tyvar)
-newTyVarTys :: Int -> Kind -> NF_TcM s [TcType s]
+newTyVarTys :: Int -> Kind -> NF_TcM [TcType]
newTyVarTys n kind = mapNF_Tc newTyVarTy (nOfThem n kind)
-newKindVar :: NF_TcM s (TcKind s)
-newKindVar = newTyVarTy superKind
+newKindVar :: NF_TcM TcKind
+newKindVar
+ = tcGetUnique `thenNF_Tc` \ uniq ->
+ tcNewMutTyVar (mkSysLocalName uniq SLIT("k")) superKind `thenNF_Tc` \ kv ->
+ returnNF_Tc (TyVarTy kv)
-newKindVars :: Int -> NF_TcM s [TcKind s]
+newKindVars :: Int -> NF_TcM [TcKind]
newKindVars n = mapNF_Tc (\ _ -> newKindVar) (nOfThem n ())
+
+newBoxityVar :: NF_TcM TcKind
+newBoxityVar
+ = tcGetUnique `thenNF_Tc` \ uniq ->
+ tcNewMutTyVar (mkSysLocalName uniq SLIT("bx")) superBoxity `thenNF_Tc` \ kv ->
+ returnNF_Tc (TyVarTy kv)
\end{code}
-Type instantiation
-~~~~~~~~~~~~~~~~~~
+
+%************************************************************************
+%* *
+\subsection{Type instantiation}
+%* *
+%************************************************************************
Instantiating a bunch of type variables
\begin{code}
-tcInstTyVars :: [GenTyVar flexi]
- -> NF_TcM s ([TcTyVar s], [TcType s], TyVarEnv (TcType s))
+tcInstTyVars :: [TyVar]
+ -> NF_TcM ([TcTyVar], [TcType], Subst)
tcInstTyVars tyvars
- = mapNF_Tc inst_tyvar tyvars `thenNF_Tc` \ tc_tyvars ->
+ = mapNF_Tc tcInstTyVar tyvars `thenNF_Tc` \ tc_tyvars ->
let
tys = mkTyVarTys tc_tyvars
in
- returnNF_Tc (tc_tyvars, tys, zipVarEnv tyvars tys)
+ returnNF_Tc (tc_tyvars, tys, mkTopTyVarSubst tyvars tys)
+ -- Since the tyvars are freshly made,
+ -- they cannot possibly be captured by
+ -- any existing for-alls. Hence mkTopTyVarSubst
-inst_tyvar tyvar -- Could use the name from the tyvar?
+tcInstTyVar tyvar
= tcGetUnique `thenNF_Tc` \ uniq ->
- tcNewMutVar UnBound `thenNF_Tc` \ box ->
let
- name = changeUnique (tyVarName tyvar) uniq
+ name = setNameUnique (tyVarName tyvar) uniq
-- Note that we don't change the print-name
-- This won't confuse the type checker but there's a chance
-- that two different tyvars will print the same way
-- Better watch out for this. If worst comes to worst, just
-- use mkSysLocalName.
in
- returnNF_Tc (mkFlexiTyVar name (tyVarKind tyvar) box)
+ tcNewMutTyVar name (tyVarKind tyvar)
+
+tcInstSigVars tyvars -- Very similar to tcInstTyVar
+ = tcGetUniques `thenNF_Tc` \ uniqs ->
+ listTc [ ASSERT( not (kind == openTypeKind) ) -- Shouldn't happen
+ tcNewSigTyVar name kind
+ | (tyvar, uniq) <- tyvars `zip` uniqs,
+ let name = setNameUnique (tyVarName tyvar) uniq,
+ let kind = tyVarKind tyvar
+ ]
\end{code}
-@tcInstTcType@ instantiates the outer-level for-alls of a TcType with
-fresh type variables, returning them and the instantiated body of the for-all.
-
+@tcInstType@ instantiates the outer-level for-alls of a TcType with
+fresh type variables, splits off the dictionary part, and returns the results.
\begin{code}
-tcInstTcType :: TcType s -> NF_TcM s ([TcTyVar s], TcType s)
-tcInstTcType ty
- = let
- (tyvars, rho) = splitForAllTys ty
- in
- case tyvars of
- [] -> returnNF_Tc ([], ty) -- Nothing to do
- other -> tcInstTyVars tyvars `thenNF_Tc` \ (tyvars', _, tenv) ->
- returnNF_Tc (tyvars', fullSubstTy tenv emptyVarSet rho)
- -- Since the tyvars are freshly made,
- -- they cannot possibly be captured by
- -- any existing for-alls. Hence emptyVarSet
+tcInstType :: TcType -> NF_TcM ([TcTyVar], TcThetaType, TcType)
+tcInstType ty
+ = case splitForAllTys ty of
+ ([], rho) -> -- There may be overloading but no type variables;
+ -- (?x :: Int) => Int -> Int
+ tcSplitRhoTy rho `thenNF_Tc` \ (theta, tau) ->
+ returnNF_Tc ([], theta, tau)
+
+ (tyvars, rho) -> tcInstTyVars tyvars `thenNF_Tc` \ (tyvars', _, tenv) ->
+ tcSplitRhoTy (substTy tenv rho) `thenNF_Tc` \ (theta, tau) ->
+ returnNF_Tc (tyvars', theta, tau)
\end{code}
-Sometimes we have to convert a Type to a TcType. I wonder whether we could
-do this less than we do?
-\begin{code}
-typeToTcType :: Type -> TcType s
-typeToTcType t = substFlexiTy emptyVarEnv t
-
-kindToTcKind :: Kind -> TcKind s
-kindToTcKind = typeToTcType
-\end{code}
+%************************************************************************
+%* *
+\subsection{Putting and getting mutable type variables}
+%* *
+%************************************************************************
-Reading and writing TcTyVars
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~
\begin{code}
-tcWriteTyVar :: TcTyVar s -> TcType s -> NF_TcM s ()
-tcReadTyVar :: TcTyVar s -> NF_TcM s (TcMaybe s)
+tcPutTyVar :: TcTyVar -> TcType -> NF_TcM TcType
+tcGetTyVar :: TcTyVar -> NF_TcM (Maybe TcType)
\end{code}
-Writing is easy:
+Putting is easy:
\begin{code}
-tcWriteTyVar tyvar ty = tcWriteMutVar (tyVarFlexi tyvar) (BoundTo ty)
+tcPutTyVar tyvar ty
+ | not (isMutTyVar tyvar)
+ = pprTrace "tcPutTyVar" (ppr tyvar) $
+ returnNF_Tc ty
+
+ | otherwise
+ = ASSERT( isMutTyVar tyvar )
+ UASSERT2( not (isUTy ty), ppr tyvar <+> ppr ty )
+ tcWriteMutTyVar tyvar (Just ty) `thenNF_Tc_`
+ returnNF_Tc ty
\end{code}
-Reading is more interesting. The easy thing to do is just to read, thus:
+Getting is more interesting. The easy thing to do is just to read, thus:
+
\begin{verbatim}
-tcReadTyVar tyvar = tcReadMutVar (tyVarFlexi tyvar)
+tcGetTyVar tyvar = tcReadMutTyVar tyvar
\end{verbatim}
But it's more fun to short out indirections on the way: If this
We return Nothing iff the original box was unbound.
\begin{code}
-tcReadTyVar tyvar
- = tcReadMutVar box `thenNF_Tc` \ maybe_ty ->
+tcGetTyVar tyvar
+ | not (isMutTyVar tyvar)
+ = pprTrace "tcGetTyVar" (ppr tyvar) $
+ returnNF_Tc (Just (mkTyVarTy tyvar))
+
+ | otherwise
+ = ASSERT2( isMutTyVar tyvar, ppr tyvar )
+ tcReadMutTyVar tyvar `thenNF_Tc` \ maybe_ty ->
case maybe_ty of
- BoundTo ty -> short_out ty `thenNF_Tc` \ ty' ->
- tcWriteMutVar box (BoundTo ty') `thenNF_Tc_`
- returnNF_Tc (BoundTo ty')
+ Just ty -> short_out ty `thenNF_Tc` \ ty' ->
+ tcWriteMutTyVar tyvar (Just ty') `thenNF_Tc_`
+ returnNF_Tc (Just ty')
- other -> returnNF_Tc other
- where
- box = tyVarFlexi tyvar
+ Nothing -> returnNF_Tc Nothing
-short_out :: TcType s -> NF_TcM s (TcType s)
+short_out :: TcType -> NF_TcM TcType
short_out ty@(TyVarTy tyvar)
- = tcReadMutVar box `thenNF_Tc` \ maybe_ty ->
+ | not (isMutTyVar tyvar)
+ = returnNF_Tc ty
+
+ | otherwise
+ = tcReadMutTyVar tyvar `thenNF_Tc` \ maybe_ty ->
case maybe_ty of
- BoundTo ty' -> short_out ty' `thenNF_Tc` \ ty' ->
- tcWriteMutVar box (BoundTo ty') `thenNF_Tc_`
- returnNF_Tc ty'
+ Just ty' -> short_out ty' `thenNF_Tc` \ ty' ->
+ tcWriteMutTyVar tyvar (Just ty') `thenNF_Tc_`
+ returnNF_Tc ty'
- other -> returnNF_Tc ty
- where
- box = tyVarFlexi tyvar
+ other -> returnNF_Tc ty
short_out other_ty = returnNF_Tc other_ty
\end{code}
-Zonking Tc types to Tc types
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+%************************************************************************
+%* *
+\subsection{Zonking -- the exernal interfaces}
+%* *
+%************************************************************************
+
+----------------- Type variables
+
\begin{code}
-zonkTcTyVars :: [TcTyVar s] -> NF_TcM s [TcType s]
+zonkTcTyVars :: [TcTyVar] -> NF_TcM [TcType]
zonkTcTyVars tyvars = mapNF_Tc zonkTcTyVar tyvars
-zonkTcTyVar :: TcTyVar s -> NF_TcM s (TcType s)
-zonkTcTyVar tyvar
- | not (isFlexiTyVar tyvar) -- Not a flexi tyvar. This can happen when
- -- zonking a forall type, when the bound type variable
- -- needn't be a flexi.
- = ASSERT( isTyVar tyvar )
- returnNF_Tc (TyVarTy tyvar)
+zonkTcTyVarsAndFV :: [TcTyVar] -> NF_TcM TcTyVarSet
+zonkTcTyVarsAndFV tyvars = mapNF_Tc zonkTcTyVar tyvars `thenNF_Tc` \ tys ->
+ returnNF_Tc (tyVarsOfTypes tys)
- | otherwise -- Is a flexi tyvar
- = tcReadTyVar tyvar `thenNF_Tc` \ maybe_ty ->
- case maybe_ty of
- BoundTo ty@(TyVarTy tyvar') -> returnNF_Tc ty -- tcReadTyVar never returns a bound tyvar
- BoundTo other -> zonkTcType other
- other -> returnNF_Tc (TyVarTy tyvar)
-
-zonkTcTyVarBndr :: TcTyVar s -> NF_TcM s (TcTyVar s)
-zonkTcTyVarBndr tyvar
- = zonkTcTyVar tyvar `thenNF_Tc` \ (TyVarTy tyvar') ->
- returnNF_Tc tyvar'
-
-zonkTcTypes :: [TcType s] -> NF_TcM s [TcType s]
-zonkTcTypes tys = mapNF_Tc zonkTcType tys
+zonkTcTyVar :: TcTyVar -> NF_TcM TcType
+zonkTcTyVar tyvar = zonkTyVar (\ tv -> returnNF_Tc (TyVarTy tv)) tyvar
-zonkTcThetaType :: TcThetaType s -> NF_TcM s (TcThetaType s)
-zonkTcThetaType theta = mapNF_Tc zonk theta
- where
- zonk (c,ts) = zonkTcTypes ts `thenNF_Tc` \ new_ts ->
- returnNF_Tc (c, new_ts)
+zonkTcSigTyVars :: [TcTyVar] -> NF_TcM [TcTyVar]
+-- This guy is to zonk the tyvars we're about to feed into tcSimplify
+-- Usually this job is done by checkSigTyVars, but in a couple of places
+-- that is overkill, so we use this simpler chap
+zonkTcSigTyVars tyvars
+ = zonkTcTyVars tyvars `thenNF_Tc` \ tys ->
+ returnNF_Tc (map (getTyVar "zonkTcSigTyVars") tys)
+\end{code}
-zonkTcKind :: TcKind s -> NF_TcM s (TcKind s)
-zonkTcKind = zonkTcType
+----------------- Types
-zonkTcType :: TcType s -> NF_TcM s (TcType s)
+\begin{code}
+zonkTcType :: TcType -> NF_TcM TcType
+zonkTcType ty = zonkType (\ tv -> returnNF_Tc (TyVarTy tv)) ty
-zonkTcType (TyVarTy tyvar) = zonkTcTyVar tyvar
+zonkTcTypes :: [TcType] -> NF_TcM [TcType]
+zonkTcTypes tys = mapNF_Tc zonkTcType tys
-zonkTcType (AppTy ty1 ty2)
- = zonkTcType ty1 `thenNF_Tc` \ ty1' ->
- zonkTcType ty2 `thenNF_Tc` \ ty2' ->
- returnNF_Tc (mkAppTy ty1' ty2')
+zonkTcClassConstraints cts = mapNF_Tc zonk cts
+ where zonk (clas, tys)
+ = zonkTcTypes tys `thenNF_Tc` \ new_tys ->
+ returnNF_Tc (clas, new_tys)
+
+zonkTcThetaType :: TcThetaType -> NF_TcM TcThetaType
+zonkTcThetaType theta = mapNF_Tc zonkTcPredType theta
+
+zonkTcPredType :: TcPredType -> NF_TcM TcPredType
+zonkTcPredType (ClassP c ts) =
+ zonkTcTypes ts `thenNF_Tc` \ new_ts ->
+ returnNF_Tc (ClassP c new_ts)
+zonkTcPredType (IParam n t) =
+ zonkTcType t `thenNF_Tc` \ new_t ->
+ returnNF_Tc (IParam n new_t)
+\end{code}
-zonkTcType (TyConApp tc tys)
- = mapNF_Tc zonkTcType tys `thenNF_Tc` \ tys' ->
- returnNF_Tc (TyConApp tc tys')
+------------------- These ...ToType, ...ToKind versions
+ are used at the end of type checking
-zonkTcType (NoteTy (SynNote ty1) ty2)
- = zonkTcType ty1 `thenNF_Tc` \ ty1' ->
- zonkTcType ty2 `thenNF_Tc` \ ty2' ->
- returnNF_Tc (NoteTy (SynNote ty1') ty2')
+\begin{code}
+zonkKindEnv :: [(Name, TcKind)] -> NF_TcM [(Name, Kind)]
+zonkKindEnv pairs
+ = mapNF_Tc zonk_it pairs
+ where
+ zonk_it (name, tc_kind) = zonkType zonk_unbound_kind_var tc_kind `thenNF_Tc` \ kind ->
+ returnNF_Tc (name, kind)
+
+ -- When zonking a kind, we want to
+ -- zonk a *kind* variable to (Type *)
+ -- zonk a *boxity* variable to *
+ zonk_unbound_kind_var kv | tyVarKind kv == superKind = tcPutTyVar kv liftedTypeKind
+ | tyVarKind kv == superBoxity = tcPutTyVar kv liftedBoxity
+ | otherwise = pprPanic "zonkKindEnv" (ppr kv)
+
+zonkTcTypeToType :: TcType -> NF_TcM Type
+zonkTcTypeToType ty = zonkType zonk_unbound_tyvar ty
+ where
+ -- Zonk a mutable but unbound type variable to
+ -- Void if it has kind Lifted
+ -- :Void otherwise
+ zonk_unbound_tyvar tv
+ | kind == liftedTypeKind || kind == openTypeKind
+ = tcPutTyVar tv voidTy -- Just to avoid creating a new tycon in
+ -- this vastly common case
+ | otherwise
+ = tcPutTyVar tv (TyConApp (mk_void_tycon tv kind) [])
+ where
+ kind = tyVarKind tv
+
+ mk_void_tycon tv kind -- Make a new TyCon with the same kind as the
+ -- type variable tv. Same name too, apart from
+ -- making it start with a colon (sigh)
+ -- I dread to think what will happen if this gets out into an
+ -- interface file. Catastrophe likely. Major sigh.
+ = pprTrace "Urk! Inventing strangely-kinded void TyCon" (ppr tc_name) $
+ mkPrimTyCon tc_name kind 0 [] VoidRep
+ where
+ tc_name = mkLocalName (getUnique tv) (mkDerivedTyConOcc (getOccName tv)) noSrcLoc
+
+-- zonkTcTyVarToTyVar is applied to the *binding* occurrence
+-- of a type variable, at the *end* of type checking. It changes
+-- the *mutable* type variable into an *immutable* one.
+--
+-- It does this by making an immutable version of tv and binds tv to it.
+-- Now any bound occurences of the original type variable will get
+-- zonked to the immutable version.
+
+zonkTcTyVarToTyVar :: TcTyVar -> NF_TcM TyVar
+zonkTcTyVarToTyVar tv
+ = let
+ -- Make an immutable version, defaulting
+ -- the kind to lifted if necessary
+ immut_tv = mkTyVar (tyVarName tv) (defaultKind (tyVarKind tv))
+ immut_tv_ty = mkTyVarTy immut_tv
-zonkTcType (NoteTy (FTVNote _) ty2) = zonkTcType ty2
+ zap tv = tcPutTyVar tv immut_tv_ty
+ -- Bind the mutable version to the immutable one
+ in
+ -- If the type variable is mutable, then bind it to immut_tv_ty
+ -- so that all other occurrences of the tyvar will get zapped too
+ zonkTyVar zap tv `thenNF_Tc` \ ty2 ->
-zonkTcType (ForAllTy tv ty)
- = zonkTcTyVar tv `thenNF_Tc` \ tv_ty ->
- zonkTcType ty `thenNF_Tc` \ ty' ->
- case tv_ty of -- Should be a tyvar!
- TyVarTy tv' -> returnNF_Tc (ForAllTy tv' ty')
- _ -> panic "zonkTcType"
- -- pprTrace "zonkTcType:ForAllTy:" (hsep [ppr tv, ppr tv_ty]) $
- -- returnNF_Tc (ForAllTy tv{-(tcTyVarToTyVar tv)-} ty')
+ WARN( immut_tv_ty /= ty2, ppr tv $$ ppr immut_tv $$ ppr ty2 )
-zonkTcType (FunTy ty1 ty2)
- = zonkTcType ty1 `thenNF_Tc` \ ty1' ->
- zonkTcType ty2 `thenNF_Tc` \ ty2' ->
- returnNF_Tc (FunTy ty1' ty2')
+ returnNF_Tc immut_tv
\end{code}
-Zonking Tc types to Type/Kind
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-\begin{code}
-zonkTcKindToKind :: TcKind s -> NF_TcM s Kind
-zonkTcKindToKind kind = zonkTcToType boxedTypeKind emptyVarEnv kind
-zonkTcTypeToType :: TyVarEnv Type -> TcType s -> NF_TcM s Type
-zonkTcTypeToType env ty = zonkTcToType voidTy env ty
+%************************************************************************
+%* *
+\subsection{Zonking -- the main work-horses: zonkType, zonkTyVar}
+%* *
+%* For internal use only! *
+%* *
+%************************************************************************
-zonkTcTyVarToTyVar :: TcTyVar s -> NF_TcM s TyVar
-zonkTcTyVarToTyVar tv
- = zonkTcTyVarBndr tv `thenNF_Tc` \ tv' ->
- returnNF_Tc (tcTyVarToTyVar tv')
+\begin{code}
+-- zonkType is used for Kinds as well
+
+-- For unbound, mutable tyvars, zonkType uses the function given to it
+-- For tyvars bound at a for-all, zonkType zonks them to an immutable
+-- type variable and zonks the kind too
--- zonkTcToType is used for Kinds as well
-zonkTcToType :: Type -> TyVarEnv Type -> TcType s -> NF_TcM s Type
-zonkTcToType unbound_var_ty env ty
+zonkType :: (TcTyVar -> NF_TcM Type) -- What to do with unbound mutable type variables
+ -- see zonkTcType, and zonkTcTypeToType
+ -> TcType
+ -> NF_TcM Type
+zonkType unbound_var_fn ty
= go ty
where
go (TyConApp tycon tys) = mapNF_Tc go tys `thenNF_Tc` \ tys' ->
go (NoteTy (FTVNote _) ty2) = go ty2 -- Discard free-tyvar annotations
+ go (PredTy p) = go_pred p `thenNF_Tc` \ p' ->
+ returnNF_Tc (PredTy p')
+
go (FunTy arg res) = go arg `thenNF_Tc` \ arg' ->
go res `thenNF_Tc` \ res' ->
returnNF_Tc (FunTy arg' res')
go arg `thenNF_Tc` \ arg' ->
returnNF_Tc (mkAppTy fun' arg')
+ go (UsageTy u ty) = go u `thenNF_Tc` \ u' ->
+ go ty `thenNF_Tc` \ ty' ->
+ returnNF_Tc (mkUTy u' ty')
+
-- The two interesting cases!
- -- c.f. zonkTcTyVar
- go (TyVarTy tyvar)
- | not (isFlexiTyVar tyvar) = lookup env tyvar
-
- | otherwise = tcReadTyVar tyvar `thenNF_Tc` \ maybe_ty ->
- case maybe_ty of
- BoundTo (TyVarTy tyvar') -> lookup env tyvar'
- BoundTo other_ty -> go other_ty
- other -> lookup env tyvar
-
- go (ForAllTy tyvar ty)
- = zonkTcTyVarToTyVar tyvar `thenNF_Tc` \ tyvar' ->
- let
- new_env = extendVarEnv env tyvar (TyVarTy tyvar')
- in
- zonkTcToType unbound_var_ty new_env ty `thenNF_Tc` \ ty' ->
- returnNF_Tc (ForAllTy tyvar' ty')
-
-
- lookup env tyvar = returnNF_Tc (case lookupVarEnv env tyvar of
- Just ty -> ty
- Nothing -> unbound_var_ty)
-\end{code}
+ go (TyVarTy tyvar) = zonkTyVar unbound_var_fn tyvar
+ go (ForAllTy tyvar ty) = zonkTcTyVarToTyVar tyvar `thenNF_Tc` \ tyvar' ->
+ go ty `thenNF_Tc` \ ty' ->
+ returnNF_Tc (ForAllTy tyvar' ty')
+
+ go_pred (ClassP c tys) = mapNF_Tc go tys `thenNF_Tc` \ tys' ->
+ returnNF_Tc (ClassP c tys')
+ go_pred (IParam n ty) = go ty `thenNF_Tc` \ ty' ->
+ returnNF_Tc (IParam n ty')
+
+zonkTyVar :: (TcTyVar -> NF_TcM Type) -- What to do for an unbound mutable variable
+ -> TcTyVar -> NF_TcM TcType
+zonkTyVar unbound_var_fn tyvar
+ | not (isMutTyVar tyvar) -- Not a mutable tyvar. This can happen when
+ -- zonking a forall type, when the bound type variable
+ -- needn't be mutable
+ = ASSERT( isTyVar tyvar ) -- Should not be any immutable kind vars
+ returnNF_Tc (TyVarTy tyvar)
+
+ | otherwise
+ = tcGetTyVar tyvar `thenNF_Tc` \ maybe_ty ->
+ case maybe_ty of
+ Nothing -> unbound_var_fn tyvar -- Mutable and unbound
+ Just other_ty -> zonkType unbound_var_fn other_ty -- Bound
+\end{code}
projects / ghc-hetmet.git / blobdiff