X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypes%2FType.lhs;h=5cf242c4050c0321ca23a50afcc732ad6e277ce6;hb=f714e6b642fd614a9971717045ae47c3d871275e;hp=4fdb337d2c091a2e55fbc5e3763d7fe88f58d57f;hpb=e4b0fab5a594c4ea29ddecdf216b4887420f26a4;p=ghc-hetmet.git diff --git a/ghc/compiler/types/Type.lhs b/ghc/compiler/types/Type.lhs index 4fdb337..5cf242c 100644 --- a/ghc/compiler/types/Type.lhs +++ b/ghc/compiler/types/Type.lhs @@ -5,69 +5,62 @@ \begin{code} module Type ( - -- re-exports from TypeRep: - Type, - Kind, TyVarSubst, - - superKind, superBoxity, -- :: SuperKind - - boxedKind, -- :: Kind :: BX - anyBoxKind, -- :: Kind :: BX - typeCon, -- :: KindCon :: BX -> KX - anyBoxCon, -- :: KindCon :: BX - - boxedTypeKind, unboxedTypeKind, openTypeKind, -- Kind :: superKind - - mkArrowKind, mkArrowKinds, -- mentioned below: hasMoreBoxityInfo, - + -- re-exports from TypeRep + TyThing(..), Type, PredType(..), ThetaType, TyVarSubst, funTyCon, - -- exports from this module: - hasMoreBoxityInfo, + -- Re-exports from Kind + module Kind, + mkTyVarTy, mkTyVarTys, getTyVar, getTyVar_maybe, isTyVarTy, mkAppTy, mkAppTys, splitAppTy, splitAppTys, splitAppTy_maybe, - mkFunTy, mkFunTys, splitFunTy, splitFunTy_maybe, splitFunTys, splitFunTysN, - funResultTy, funArgTy, zipFunTys, - - mkTyConApp, mkTyConTy, splitTyConApp_maybe, - splitAlgTyConApp_maybe, splitAlgTyConApp, - mkDictTy, mkPredTy, splitPredTy_maybe, splitDictTy_maybe, isDictTy, + mkFunTy, mkFunTys, splitFunTy, splitFunTy_maybe, splitFunTys, + funResultTy, funArgTy, zipFunTys, isFunTy, - mkSynTy, isSynTy, deNoteType, + mkGenTyConApp, mkTyConApp, mkTyConTy, + tyConAppTyCon, tyConAppArgs, + splitTyConApp_maybe, splitTyConApp, - repType, splitRepFunTys, splitNewType_maybe, typePrimRep, + mkSynTy, - UsageAnn(..), mkUsgTy, isUsgTy{- dont use -}, isNotUsgTy, splitUsgTy, unUsgTy, tyUsg, - mkUsForAllTy, mkUsForAllTys, splitUsForAllTys, substUsTy, + repType, typePrimRep, mkForAllTy, mkForAllTys, splitForAllTy_maybe, splitForAllTys, - isForAllTy, applyTy, applyTys, mkPiType, hoistForAllTys, + applyTy, applyTys, isForAllTy, dropForAlls, - TauType, RhoType, SigmaType, PredType(..), ThetaType, - ClassPred, ClassContext, mkClassPred, - getClassTys_maybe, ipName_maybe, classesToPreds, classesOfPreds, - isTauTy, mkRhoTy, splitRhoTy, - mkSigmaTy, splitSigmaTy, + -- Source types + predTypeRep, mkPredTy, mkPredTys, + + -- Newtypes + splitRecNewType_maybe, -- Lifting and boxity - isUnLiftedType, isUnboxedType, isUnboxedTupleType, isAlgType, isDataType, isNewType, + isUnLiftedType, isUnboxedTupleType, isAlgType, isPrimitiveType, + isStrictType, isStrictPred, -- Free variables tyVarsOfType, tyVarsOfTypes, tyVarsOfPred, tyVarsOfTheta, - namesOfType, typeKind, addFreeTyVars, + typeKind, addFreeTyVars, -- Tidying up for printing - tidyType, tidyTypes, - tidyOpenType, tidyOpenTypes, - tidyTyVar, tidyTyVars, - tidyTopType, + tidyType, tidyTypes, + tidyOpenType, tidyOpenTypes, + tidyTyVarBndr, tidyFreeTyVars, + tidyOpenTyVar, tidyOpenTyVars, + tidyTopType, tidyPred, + + -- Comparison + eqType, -- Seq - seqType, seqTypes + seqType, seqTypes, + -- Pretty-printing + pprType, pprParendType, + pprPred, pprTheta, pprThetaArrow, pprClassPred ) where #include "HsVersions.h" @@ -79,56 +72,33 @@ import TypeRep -- Other imports: -import {-# SOURCE #-} DataCon( DataCon, dataConRepType ) -import {-# SOURCE #-} PprType( pprType, pprPred ) -- Only called in debug messages -import {-# SOURCE #-} Subst ( mkTyVarSubst, substTy ) +import {-# SOURCE #-} Subst ( substTyWith ) -- friends: -import Var ( TyVar, Var, UVar, - tyVarKind, tyVarName, setTyVarName, isId, idType, - ) +import Kind +import Var ( TyVar, tyVarKind, tyVarName, setTyVarName ) import VarEnv import VarSet -import Name ( Name, NamedThing(..), mkLocalName, tidyOccName - ) -import NameSet -import Class ( classTyCon, Class ) -import TyCon ( TyCon, +import Name ( NamedThing(..), mkInternalName, tidyOccName ) +import Class ( Class, classTyCon ) +import TyCon ( TyCon, isRecursiveTyCon, isPrimTyCon, isUnboxedTupleTyCon, isUnLiftedTyCon, - isFunTyCon, isDataTyCon, isNewTyCon, newTyConRep, - isAlgTyCon, isSynTyCon, tyConArity, - tyConKind, tyConDataCons, getSynTyConDefn, - tyConPrimRep, tyConClass_maybe + isFunTyCon, isNewTyCon, newTyConRep, + isAlgTyCon, isSynTyCon, tyConArity, + tyConKind, getSynTyConDefn, + tyConPrimRep, ) -- others +import CmdLineOpts ( opt_DictsStrict ) import SrcLoc ( noSrcLoc ) -import Maybes ( maybeToBool ) -import PrimRep ( PrimRep(..), isFollowableRep ) +import PrimRep ( PrimRep(..) ) import Unique ( Uniquable(..) ) -import Util ( mapAccumL, seqList ) +import Util ( mapAccumL, seqList, lengthIs, snocView ) import Outputable import UniqSet ( sizeUniqSet ) -- Should come via VarSet -\end{code} - - -%************************************************************************ -%* * -\subsection{Stuff to do with kinds.} -%* * -%************************************************************************ - -\begin{code} -hasMoreBoxityInfo :: Kind -> Kind -> Bool -hasMoreBoxityInfo k1 k2 - | k2 == openTypeKind = ASSERT( is_type_kind k1) True - | otherwise = k1 == k2 - where - -- Returns true for things of form (Type x) - is_type_kind k = case splitTyConApp_maybe k of - Just (tc,[_]) -> tc == typeCon - Nothing -> False +import Maybe ( isJust ) \end{code} @@ -150,19 +120,19 @@ mkTyVarTys :: [TyVar] -> [Type] mkTyVarTys = map mkTyVarTy -- a common use of mkTyVarTy getTyVar :: String -> Type -> TyVar -getTyVar msg (TyVarTy tv) = tv -getTyVar msg (NoteTy _ t) = getTyVar msg t -getTyVar msg other = panic ("getTyVar: " ++ msg) - -getTyVar_maybe :: Type -> Maybe TyVar -getTyVar_maybe (TyVarTy tv) = Just tv -getTyVar_maybe (NoteTy _ t) = getTyVar_maybe t -getTyVar_maybe other = Nothing +getTyVar msg ty = case getTyVar_maybe ty of + Just tv -> tv + Nothing -> panic ("getTyVar: " ++ msg) isTyVarTy :: Type -> Bool -isTyVarTy (TyVarTy tv) = True -isTyVarTy (NoteTy _ ty) = isTyVarTy ty -isTyVarTy other = False +isTyVarTy ty = isJust (getTyVar_maybe ty) + +getTyVar_maybe :: Type -> Maybe TyVar +getTyVar_maybe (TyVarTy tv) = Just tv +getTyVar_maybe (NoteTy _ t) = getTyVar_maybe t +getTyVar_maybe (PredTy p) = getTyVar_maybe (predTypeRep p) +getTyVar_maybe (NewTcApp tc tys) = getTyVar_maybe (newTypeRep tc tys) +getTyVar_maybe other = Nothing \end{code} @@ -174,39 +144,50 @@ invariant that a TyConApp is always visibly so. mkAppTy maintains the invariant: use it. \begin{code} -mkAppTy orig_ty1 orig_ty2 = ASSERT2( isNotUsgTy orig_ty1 && isNotUsgTy orig_ty2, pprType orig_ty1 <+> text "to" <+> pprType orig_ty2 ) - mk_app orig_ty1 +mkAppTy orig_ty1 orig_ty2 + = mk_app orig_ty1 where mk_app (NoteTy _ ty1) = mk_app ty1 - mk_app (TyConApp tc tys) = mkTyConApp tc (tys ++ [orig_ty2]) + mk_app (NewTcApp tc tys) = NewTcApp tc (tys ++ [orig_ty2]) + mk_app (TyConApp tc tys) = mkGenTyConApp tc (tys ++ [orig_ty2]) mk_app ty1 = AppTy orig_ty1 orig_ty2 + -- We call mkGenTyConApp because the TyConApp could be an + -- under-saturated type synonym. GHC allows that; e.g. + -- type Foo k = k a -> k a + -- type Id x = x + -- foo :: Foo Id -> Foo Id + -- + -- Here Id is partially applied in the type sig for Foo, + -- but once the type synonyms are expanded all is well mkAppTys :: Type -> [Type] -> Type mkAppTys orig_ty1 [] = orig_ty1 -- This check for an empty list of type arguments - -- avoids the needless of a type synonym constructor. + -- avoids the needless loss of a type synonym constructor. -- For example: mkAppTys Rational [] -- returns to (Ratio Integer), which has needlessly lost -- the Rational part. -mkAppTys orig_ty1 orig_tys2 = ASSERT2( isNotUsgTy orig_ty1, pprType orig_ty1 ) - mk_app orig_ty1 +mkAppTys orig_ty1 orig_tys2 + = mk_app orig_ty1 where mk_app (NoteTy _ ty1) = mk_app ty1 + mk_app (NewTcApp tc tys) = NewTcApp tc (tys ++ orig_tys2) mk_app (TyConApp tc tys) = mkTyConApp tc (tys ++ orig_tys2) - mk_app ty1 = ASSERT2( all isNotUsgTy orig_tys2, pprType orig_ty1 <+> text "to" <+> hsep (map pprType orig_tys2) ) - foldl AppTy orig_ty1 orig_tys2 + -- Use mkTyConApp in case tc is (->) + mk_app ty1 = foldl AppTy orig_ty1 orig_tys2 splitAppTy_maybe :: Type -> Maybe (Type, Type) splitAppTy_maybe (FunTy ty1 ty2) = Just (TyConApp funTyCon [ty1], ty2) splitAppTy_maybe (AppTy ty1 ty2) = Just (ty1, ty2) splitAppTy_maybe (NoteTy _ ty) = splitAppTy_maybe ty -splitAppTy_maybe (TyConApp tc []) = Nothing -splitAppTy_maybe (TyConApp tc tys) = split tys [] - where - split [ty2] acc = Just (TyConApp tc (reverse acc), ty2) - split (ty:tys) acc = split tys (ty:acc) +splitAppTy_maybe (PredTy p) = splitAppTy_maybe (predTypeRep p) +splitAppTy_maybe (NewTcApp tc tys) = splitAppTy_maybe (newTypeRep tc tys) +splitAppTy_maybe (TyConApp tc tys) = case snocView tys of + Nothing -> Nothing + Just (tys',ty') -> Just (mkGenTyConApp tc tys', ty') + -- mkGenTyConApp just in case the tc is a newtype -splitAppTy_maybe other = Nothing +splitAppTy_maybe other = Nothing splitAppTy :: Type -> (Type, Type) splitAppTy ty = case splitAppTy_maybe ty of @@ -218,9 +199,12 @@ splitAppTys ty = split ty ty [] where split orig_ty (AppTy ty arg) args = split ty ty (arg:args) split orig_ty (NoteTy _ ty) args = split orig_ty ty args + split orig_ty (PredTy p) args = split orig_ty (predTypeRep p) args + split orig_ty (NewTcApp tc tc_args) args = split orig_ty (newTypeRep tc tc_args) args + split orig_ty (TyConApp tc tc_args) args = (mkGenTyConApp tc [], tc_args ++ args) + -- mkGenTyConApp just in case the tc is a newtype split orig_ty (FunTy ty1 ty2) args = ASSERT( null args ) (TyConApp funTyCon [], [ty1,ty2]) - split orig_ty (TyConApp tc tc_args) args = (TyConApp tc [], tc_args ++ args) split orig_ty ty args = (orig_ty, args) \end{code} @@ -236,176 +220,139 @@ mkFunTy arg res = FunTy arg res mkFunTys :: [Type] -> Type -> Type mkFunTys tys ty = foldr FunTy ty tys +isFunTy :: Type -> Bool +isFunTy ty = isJust (splitFunTy_maybe ty) + splitFunTy :: Type -> (Type, Type) -splitFunTy (FunTy arg res) = (arg, res) -splitFunTy (NoteTy _ ty) = splitFunTy ty +splitFunTy (FunTy arg res) = (arg, res) +splitFunTy (NoteTy _ ty) = splitFunTy ty +splitFunTy (PredTy p) = splitFunTy (predTypeRep p) +splitFunTy (NewTcApp tc tys) = splitFunTy (newTypeRep tc tys) +splitFunTy other = pprPanic "splitFunTy" (ppr other) splitFunTy_maybe :: Type -> Maybe (Type, Type) -splitFunTy_maybe (FunTy arg res) = Just (arg, res) -splitFunTy_maybe (NoteTy _ ty) = splitFunTy_maybe ty -splitFunTy_maybe other = Nothing +splitFunTy_maybe (FunTy arg res) = Just (arg, res) +splitFunTy_maybe (NoteTy _ ty) = splitFunTy_maybe ty +splitFunTy_maybe (PredTy p) = splitFunTy_maybe (predTypeRep p) +splitFunTy_maybe (NewTcApp tc tys) = splitFunTy_maybe (newTypeRep tc tys) +splitFunTy_maybe other = Nothing splitFunTys :: Type -> ([Type], Type) splitFunTys ty = split [] ty ty where - split args orig_ty (FunTy arg res) = split (arg:args) res res - split args orig_ty (NoteTy _ ty) = split args orig_ty ty - split args orig_ty ty = (reverse args, orig_ty) - -splitFunTysN :: String -> Int -> Type -> ([Type], Type) -splitFunTysN msg orig_n orig_ty = split orig_n [] orig_ty orig_ty - where - split 0 args syn_ty ty = (reverse args, syn_ty) - split n args syn_ty (FunTy arg res) = split (n-1) (arg:args) res res - split n args syn_ty (NoteTy _ ty) = split n args syn_ty ty - split n args syn_ty ty = pprPanic ("splitFunTysN: " ++ msg) (int orig_n <+> pprType orig_ty) + split args orig_ty (FunTy arg res) = split (arg:args) res res + split args orig_ty (NoteTy _ ty) = split args orig_ty ty + split args orig_ty (PredTy p) = split args orig_ty (predTypeRep p) + split args orig_ty (NewTcApp tc tys) = split args orig_ty (newTypeRep tc tys) + split args orig_ty ty = (reverse args, orig_ty) zipFunTys :: Outputable a => [a] -> Type -> ([(a,Type)], Type) zipFunTys orig_xs orig_ty = split [] orig_xs orig_ty orig_ty where - split acc [] nty ty = (reverse acc, nty) - split acc (x:xs) nty (FunTy arg res) = split ((x,arg):acc) xs res res - split acc xs nty (NoteTy _ ty) = split acc xs nty ty - split acc (x:xs) nty ty = pprPanic "zipFunTys" (ppr orig_xs <+> pprType orig_ty) + split acc [] nty ty = (reverse acc, nty) + split acc (x:xs) nty (FunTy arg res) = split ((x,arg):acc) xs res res + split acc xs nty (NoteTy _ ty) = split acc xs nty ty + split acc xs nty (PredTy p) = split acc xs nty (predTypeRep p) + split acc xs nty (NewTcApp tc tys) = split acc xs nty (newTypeRep tc tys) + split acc (x:xs) nty ty = pprPanic "zipFunTys" (ppr orig_xs <+> ppr orig_ty) funResultTy :: Type -> Type -funResultTy (FunTy arg res) = res -funResultTy (NoteTy _ ty) = funResultTy ty -funResultTy ty = pprPanic "funResultTy" (pprType ty) +funResultTy (FunTy arg res) = res +funResultTy (NoteTy _ ty) = funResultTy ty +funResultTy (PredTy p) = funResultTy (predTypeRep p) +funResultTy (NewTcApp tc tys) = funResultTy (newTypeRep tc tys) +funResultTy ty = pprPanic "funResultTy" (ppr ty) funArgTy :: Type -> Type -funArgTy (FunTy arg res) = arg -funArgTy (NoteTy _ ty) = funArgTy ty -funArgTy ty = pprPanic "funArgTy" (pprType ty) +funArgTy (FunTy arg res) = arg +funArgTy (NoteTy _ ty) = funArgTy ty +funArgTy (PredTy p) = funArgTy (predTypeRep p) +funArgTy (NewTcApp tc tys) = funArgTy (newTypeRep tc tys) +funArgTy ty = pprPanic "funArgTy" (ppr ty) \end{code} --------------------------------------------------------------------- TyConApp ~~~~~~~~ +@mkTyConApp@ is a key function, because it builds a TyConApp, FunTy or PredTy, +as apppropriate. \begin{code} +mkGenTyConApp :: TyCon -> [Type] -> Type +mkGenTyConApp tc tys + | isSynTyCon tc = mkSynTy tc tys + | otherwise = mkTyConApp tc tys + mkTyConApp :: TyCon -> [Type] -> Type +-- Assumes TyCon is not a SynTyCon; use mkSynTy instead for those mkTyConApp tycon tys - | isFunTyCon tycon && length tys == 2 - = case tys of - (ty1:ty2:_) -> FunTy ty1 ty2 + | isFunTyCon tycon, [ty1,ty2] <- tys + = FunTy ty1 ty2 + + | isNewTyCon tycon + = NewTcApp tycon tys | otherwise = ASSERT(not (isSynTyCon tycon)) TyConApp tycon tys mkTyConTy :: TyCon -> Type -mkTyConTy tycon = ASSERT( not (isSynTyCon tycon) ) - TyConApp tycon [] +mkTyConTy tycon = mkTyConApp tycon [] -- splitTyConApp "looks through" synonyms, because they don't -- mean a distinct type, but all other type-constructor applications -- including functions are returned as Just .. +tyConAppTyCon :: Type -> TyCon +tyConAppTyCon ty = fst (splitTyConApp ty) + +tyConAppArgs :: Type -> [Type] +tyConAppArgs ty = snd (splitTyConApp ty) + +splitTyConApp :: Type -> (TyCon, [Type]) +splitTyConApp ty = case splitTyConApp_maybe ty of + Just stuff -> stuff + Nothing -> pprPanic "splitTyConApp" (ppr ty) + splitTyConApp_maybe :: Type -> Maybe (TyCon, [Type]) splitTyConApp_maybe (TyConApp tc tys) = Just (tc, tys) splitTyConApp_maybe (FunTy arg res) = Just (funTyCon, [arg,res]) splitTyConApp_maybe (NoteTy _ ty) = splitTyConApp_maybe ty +splitTyConApp_maybe (PredTy p) = splitTyConApp_maybe (predTypeRep p) +splitTyConApp_maybe (NewTcApp tc tys) = splitTyConApp_maybe (newTypeRep tc tys) splitTyConApp_maybe other = Nothing - --- splitAlgTyConApp_maybe looks for --- *saturated* applications of *algebraic* data types --- "Algebraic" => newtype, data type, or dictionary (not function types) --- We return the constructors too. - -splitAlgTyConApp_maybe :: Type -> Maybe (TyCon, [Type], [DataCon]) -splitAlgTyConApp_maybe (TyConApp tc tys) - | isAlgTyCon tc && - tyConArity tc == length tys = Just (tc, tys, tyConDataCons tc) -splitAlgTyConApp_maybe (NoteTy _ ty) = splitAlgTyConApp_maybe ty -splitAlgTyConApp_maybe other = Nothing - -splitAlgTyConApp :: Type -> (TyCon, [Type], [DataCon]) - -- Here the "algebraic" property is an *assertion* -splitAlgTyConApp (TyConApp tc tys) = ASSERT( isAlgTyCon tc && tyConArity tc == length tys ) - (tc, tys, tyConDataCons tc) -splitAlgTyConApp (NoteTy _ ty) = splitAlgTyConApp ty \end{code} -"Dictionary" types are just ordinary data types, but you can -tell from the type constructor whether it's a dictionary or not. - -\begin{code} -mkDictTy :: Class -> [Type] -> Type -mkDictTy clas tys = TyConApp (classTyCon clas) tys - -mkPredTy :: PredType -> Type -mkPredTy (Class clas tys) = TyConApp (classTyCon clas) tys -mkPredTy (IParam n ty) = NoteTy (IPNote n) ty - -{- -splitDictTy_maybe :: Type -> Maybe (Class, [Type]) -splitDictTy_maybe (TyConApp tc tys) - | maybeToBool maybe_class - && tyConArity tc == length tys = Just (clas, tys) - where - maybe_class = tyConClass_maybe tc - Just clas = maybe_class - -splitDictTy_maybe (NoteTy _ ty) = splitDictTy_maybe ty -splitDictTy_maybe other = Nothing --} - -splitPredTy_maybe :: Type -> Maybe PredType -splitPredTy_maybe (TyConApp tc tys) - | maybeToBool maybe_class - && tyConArity tc == length tys = Just (Class clas tys) - where - maybe_class = tyConClass_maybe tc - Just clas = maybe_class - -splitPredTy_maybe (NoteTy (IPNote n) ty) - = Just (IParam n ty) -splitPredTy_maybe (NoteTy _ ty) = splitPredTy_maybe ty -splitPredTy_maybe other = Nothing - -splitDictTy_maybe :: Type -> Maybe (Class, [Type]) -splitDictTy_maybe ty - = case splitPredTy_maybe ty of - Just p -> getClassTys_maybe p - Nothing -> Nothing - -isDictTy :: Type -> Bool - -- This version is slightly more efficient than (maybeToBool . splitDictTy) -isDictTy (TyConApp tc tys) - | maybeToBool (tyConClass_maybe tc) - && tyConArity tc == length tys - = True -isDictTy (NoteTy _ ty) = isDictTy ty -isDictTy other = False -\end{code} --------------------------------------------------------------------- SynTy ~~~~~ \begin{code} -mkSynTy syn_tycon tys - = ASSERT( isSynTyCon syn_tycon ) - ASSERT( isNotUsgTy body ) - ASSERT( length tyvars == length tys ) - NoteTy (SynNote (TyConApp syn_tycon tys)) - (substTy (mkTyVarSubst tyvars tys) body) +mkSynTy tycon tys + | n_args == arity -- Exactly saturated + = mk_syn tys + | n_args > arity -- Over-saturated + = case splitAt arity tys of { (as,bs) -> mkAppTys (mk_syn as) bs } + -- Its important to use mkAppTys, rather than (foldl AppTy), + -- because (mk_syn as) might well return a partially-applied + -- type constructor; indeed, usually will! + | otherwise -- Un-saturated + = TyConApp tycon tys + -- For the un-saturated case we build TyConApp directly + -- (mkTyConApp ASSERTs that the tc isn't a SynTyCon). + -- Here we are relying on checkValidType to find + -- the error. What we can't do is use mkSynTy with + -- too few arg tys, because that is utterly bogus. + where - (tyvars, body) = getSynTyConDefn syn_tycon - -isSynTy (NoteTy (SynNote _) _) = True -isSynTy other = False - -deNoteType :: Type -> Type - -- Sorry for the cute name -deNoteType ty@(TyVarTy tyvar) = ty -deNoteType (TyConApp tycon tys) = TyConApp tycon (map deNoteType tys) -deNoteType (NoteTy _ ty) = deNoteType ty -deNoteType (AppTy fun arg) = AppTy (deNoteType fun) (deNoteType arg) -deNoteType (FunTy fun arg) = FunTy (deNoteType fun) (deNoteType arg) -deNoteType (ForAllTy tv ty) = ForAllTy tv (deNoteType ty) + mk_syn tys = NoteTy (SynNote (TyConApp tycon tys)) + (substTyWith tyvars tys body) + + (tyvars, body) = ASSERT( isSynTyCon tycon ) getSynTyConDefn tycon + arity = tyConArity tycon + n_args = length tys \end{code} Notes on type synonyms @@ -425,28 +372,24 @@ interfaces. Notably this plays a role in tcTySigs in TcBinds.lhs. Representation types ~~~~~~~~~~~~~~~~~~~~ - repType looks through (a) for-alls, and - (b) newtypes - (c) synonyms -It's useful in the back end where we're not -interested in newtypes anymore. + (b) synonyms + (c) predicates + (d) usage annotations + (e) [recursive] newtypes +It's useful in the back end. \begin{code} repType :: Type -> Type -repType (ForAllTy _ ty) = repType ty -repType (NoteTy _ ty) = repType ty -repType ty = case splitNewType_maybe ty of - Just ty' -> repType ty' -- Still re-apply repType in case of for-all - Nothing -> ty - -splitRepFunTys :: Type -> ([Type], Type) --- Like splitFunTys, but looks through newtypes and for-alls -splitRepFunTys ty = split [] (repType ty) - where - split args (FunTy arg res) = split (arg:args) (repType res) - split args ty = (reverse args, ty) +-- Only applied to types of kind *; hence tycons are saturated +repType (ForAllTy _ ty) = repType ty +repType (NoteTy _ ty) = repType ty +repType (PredTy p) = repType (predTypeRep p) +repType (NewTcApp tc tys) = ASSERT( tys `lengthIs` tyConArity tc ) + repType (new_type_rep tc tys) +repType ty = ty + typePrimRep :: Type -> PrimRep typePrimRep ty = case repType ty of @@ -454,314 +397,173 @@ typePrimRep ty = case repType ty of FunTy _ _ -> PtrRep AppTy _ _ -> PtrRep -- ?? TyVarTy _ -> PtrRep - -splitNewType_maybe :: Type -> Maybe Type --- Find the representation of a newtype, if it is one --- Looks through multiple levels of newtype, but does not look through for-alls -splitNewType_maybe (NoteTy _ ty) = splitNewType_maybe ty -splitNewType_maybe (TyConApp tc tys) = case newTyConRep tc of - Just rep_ty -> ASSERT( length tys == tyConArity tc ) - -- The assert should hold because repType should - -- only be applied to *types* (of kind *) - Just (applyTys rep_ty tys) - Nothing -> Nothing -splitNewType_maybe other = Nothing + other -> pprPanic "typePrimRep" (ppr ty) \end{code} --------------------------------------------------------------------- - UsgNote - ~~~~~~~ - -NB: Invariant: if present, usage note is at the very top of the type. -This should be carefully preserved. - -In some parts of the compiler, comments use the _Once Upon a -Polymorphic Type_ (POPL'99) usage of "rho = generalised -usage-annotated type; sigma = usage-annotated type; tau = -usage-annotated type except on top"; unfortunately this conflicts with -the rho/tau/theta/sigma usage in the rest of the compiler. (KSW -1999-07) - -\begin{code} -mkUsgTy :: UsageAnn -> Type -> Type -#ifndef USMANY -mkUsgTy UsMany ty = ASSERT2( isNotUsgTy ty, pprType ty ) - ty -#endif -mkUsgTy usg ty = ASSERT2( isNotUsgTy ty, pprType ty ) - NoteTy (UsgNote usg) ty - --- The isUsgTy function is utterly useless if UsManys are omitted. --- Be warned! KSW 1999-04. -isUsgTy :: Type -> Bool -#ifndef USMANY -isUsgTy _ = True -#else -isUsgTy (NoteTy (UsgForAll _) ty) = isUsgTy ty -isUsgTy (NoteTy (UsgNote _) _ ) = True -isUsgTy other = False -#endif - --- The isNotUsgTy function may return a false True if UsManys are omitted; --- in other words, A SSERT( isNotUsgTy ty ) may be useful but --- A SSERT( not (isNotUsg ty) ) is asking for trouble. KSW 1999-04. -isNotUsgTy :: Type -> Bool -isNotUsgTy (NoteTy (UsgForAll _) _) = False -isNotUsgTy (NoteTy (UsgNote _) _) = False -isNotUsgTy other = True - --- splitUsgTy_maybe is not exported, since it is meaningless if --- UsManys are omitted. It is used in several places in this module, --- however. KSW 1999-04. -splitUsgTy_maybe :: Type -> Maybe (UsageAnn,Type) -splitUsgTy_maybe (NoteTy (UsgNote usg) ty2) = ASSERT( isNotUsgTy ty2 ) - Just (usg,ty2) -splitUsgTy_maybe ty@(NoteTy (UsgForAll _) _) = pprPanic "splitUsgTy_maybe:" $ pprType ty -splitUsgTy_maybe ty = Nothing - -splitUsgTy :: Type -> (UsageAnn,Type) -splitUsgTy ty = case splitUsgTy_maybe ty of - Just ans -> ans - Nothing -> -#ifndef USMANY - (UsMany,ty) -#else - pprPanic "splitUsgTy: no usage annot:" $ pprType ty -#endif - -tyUsg :: Type -> UsageAnn -tyUsg = fst . splitUsgTy - -unUsgTy :: Type -> Type --- strip outer usage annotation if present -unUsgTy ty = case splitUsgTy_maybe ty of - Just (_,ty1) -> ASSERT2( isNotUsgTy ty1, pprType ty ) - ty1 - Nothing -> ty - -mkUsForAllTy :: UVar -> Type -> Type -mkUsForAllTy uv ty = NoteTy (UsgForAll uv) ty - -mkUsForAllTys :: [UVar] -> Type -> Type -mkUsForAllTys uvs ty = foldr (NoteTy . UsgForAll) ty uvs - -splitUsForAllTys :: Type -> ([UVar],Type) -splitUsForAllTys ty = split ty [] - where split (NoteTy (UsgForAll u) ty) uvs = split ty (u:uvs) - split other_ty uvs = (reverse uvs, other_ty) - -substUsTy :: VarEnv UsageAnn -> Type -> Type --- assumes range is fresh uvars, so no conflicts -substUsTy ve (NoteTy note@(UsgNote (UsVar u)) - ty ) = NoteTy (case lookupVarEnv ve u of - Just ua -> UsgNote ua - Nothing -> note) - (substUsTy ve ty) -substUsTy ve (NoteTy note@(UsgNote _) ty ) = NoteTy note (substUsTy ve ty) -substUsTy ve (NoteTy note@(UsgForAll _) ty ) = NoteTy note (substUsTy ve ty) -substUsTy ve (NoteTy (SynNote ty1) ty2) = NoteTy (SynNote (substUsTy ve ty1)) - (substUsTy ve ty2) -substUsTy ve (NoteTy note@(FTVNote _) ty ) = NoteTy note (substUsTy ve ty) -substUsTy ve ty@(TyVarTy _ ) = ty -substUsTy ve (AppTy ty1 ty2) = AppTy (substUsTy ve ty1) - (substUsTy ve ty2) -substUsTy ve (FunTy ty1 ty2) = FunTy (substUsTy ve ty1) - (substUsTy ve ty2) -substUsTy ve (TyConApp tyc tys) = TyConApp tyc (map (substUsTy ve) tys) -substUsTy ve (ForAllTy yv ty ) = ForAllTy yv (substUsTy ve ty) -\end{code} - - ---------------------------------------------------------------------- ForAllTy ~~~~~~~~ -We need to be clever here with usage annotations; they need to be -lifted or lowered through the forall as appropriate. - \begin{code} mkForAllTy :: TyVar -> Type -> Type -mkForAllTy tyvar ty = case splitUsgTy_maybe ty of - Just (usg,ty') -> NoteTy (UsgNote usg) - (ForAllTy tyvar ty') - Nothing -> ForAllTy tyvar ty +mkForAllTy tyvar ty + = mkForAllTys [tyvar] ty mkForAllTys :: [TyVar] -> Type -> Type -mkForAllTys tyvars ty = case splitUsgTy_maybe ty of - Just (usg,ty') -> NoteTy (UsgNote usg) - (foldr ForAllTy ty' tyvars) - Nothing -> foldr ForAllTy ty tyvars +mkForAllTys tyvars ty = foldr ForAllTy ty tyvars + +isForAllTy :: Type -> Bool +isForAllTy (NoteTy _ ty) = isForAllTy ty +isForAllTy (ForAllTy _ _) = True +isForAllTy other_ty = False splitForAllTy_maybe :: Type -> Maybe (TyVar, Type) -splitForAllTy_maybe ty = case splitUsgTy_maybe ty of - Just (usg,ty') -> do (tyvar,ty'') <- splitFAT_m ty' - return (tyvar, NoteTy (UsgNote usg) ty'') - Nothing -> splitFAT_m ty +splitForAllTy_maybe ty = splitFAT_m ty where - splitFAT_m (NoteTy _ ty) = splitFAT_m ty - splitFAT_m (ForAllTy tyvar ty) = Just(tyvar, ty) - splitFAT_m _ = Nothing - -isForAllTy :: Type -> Bool -isForAllTy (NoteTy _ ty) = isForAllTy ty -isForAllTy (ForAllTy tyvar ty) = True -isForAllTy _ = False + splitFAT_m (NoteTy _ ty) = splitFAT_m ty + splitFAT_m (PredTy p) = splitFAT_m (predTypeRep p) + splitFAT_m (NewTcApp tc tys) = splitFAT_m (newTypeRep tc tys) + splitFAT_m (ForAllTy tyvar ty) = Just(tyvar, ty) + splitFAT_m _ = Nothing splitForAllTys :: Type -> ([TyVar], Type) -splitForAllTys ty = case splitUsgTy_maybe ty of - Just (usg,ty') -> let (tvs,ty'') = split ty' ty' [] - in (tvs, NoteTy (UsgNote usg) ty'') - Nothing -> split ty ty [] +splitForAllTys ty = split ty ty [] where - split orig_ty (ForAllTy tv ty) tvs = split ty ty (tv:tvs) - split orig_ty (NoteTy _ ty) tvs = split orig_ty ty tvs - split orig_ty t tvs = (reverse tvs, orig_ty) + split orig_ty (ForAllTy tv ty) tvs = split ty ty (tv:tvs) + split orig_ty (NoteTy _ ty) tvs = split orig_ty ty tvs + split orig_ty (PredTy p) tvs = split orig_ty (predTypeRep p) tvs + split orig_ty (NewTcApp tc tys) tvs = split orig_ty (newTypeRep tc tys) tvs + split orig_ty t tvs = (reverse tvs, orig_ty) + +dropForAlls :: Type -> Type +dropForAlls ty = snd (splitForAllTys ty) \end{code} -@mkPiType@ makes a (->) type or a forall type, depending on whether -it is given a type variable or a term variable. - -\begin{code} -mkPiType :: Var -> Type -> Type -- The more polymorphic version doesn't work... -mkPiType v ty | isId v = mkFunTy (idType v) ty - | otherwise = mkForAllTy v ty -\end{code} +-- (mkPiType now in CoreUtils) -Applying a for-all to its arguments +applyTy, applyTys +~~~~~~~~~~~~~~~~~ +Instantiate a for-all type with one or more type arguments. +Used when we have a polymorphic function applied to type args: + f t1 t2 +Then we use (applyTys type-of-f [t1,t2]) to compute the type of +the expression. \begin{code} applyTy :: Type -> Type -> Type -applyTy (NoteTy note@(UsgNote _) fun) arg = NoteTy note (applyTy fun arg) -applyTy (NoteTy note@(UsgForAll _) fun) arg = NoteTy note (applyTy fun arg) -applyTy (NoteTy _ fun) arg = applyTy fun arg -applyTy (ForAllTy tv ty) arg = ASSERT( isNotUsgTy arg ) - substTy (mkTyVarSubst [tv] [arg]) ty -applyTy other arg = panic "applyTy" +applyTy (PredTy p) arg = applyTy (predTypeRep p) arg +applyTy (NewTcApp tc tys) arg = applyTy (newTypeRep tc tys) arg +applyTy (NoteTy _ fun) arg = applyTy fun arg +applyTy (ForAllTy tv ty) arg = substTyWith [tv] [arg] ty +applyTy other arg = panic "applyTy" applyTys :: Type -> [Type] -> Type -applyTys fun_ty arg_tys - = substTy (mkTyVarSubst tvs arg_tys) ty - where - (tvs, ty) = split fun_ty arg_tys - - split fun_ty [] = ([], fun_ty) - split (NoteTy note@(UsgNote _) fun_ty) - args = case split fun_ty args of - (tvs, ty) -> (tvs, NoteTy note ty) - split (NoteTy note@(UsgForAll _) fun_ty) - args = case split fun_ty args of - (tvs, ty) -> (tvs, NoteTy note ty) - split (NoteTy _ fun_ty) args = split fun_ty args - split (ForAllTy tv fun_ty) (arg:args) = ASSERT2( isNotUsgTy arg, vcat (map pprType arg_tys) $$ - text "in application of" <+> pprType fun_ty) - case split fun_ty args of - (tvs, ty) -> (tv:tvs, ty) - split other_ty args = panic "applyTys" -\end{code} - -Note that we allow applications to be of usage-annotated- types, as an -extension: we handle them by lifting the annotation outside. The -argument, however, must still be unannotated. - -\begin{code} -hoistForAllTys :: Type -> Type - -- Move all the foralls to the top - -- e.g. T -> forall a. a ==> forall a. T -> a -hoistForAllTys ty - = case hoist ty of { (tvs, body) -> mkForAllTys tvs body } +-- This function is interesting because +-- a) the function may have more for-alls than there are args +-- b) less obviously, it may have fewer for-alls +-- For case (b) think of +-- applyTys (forall a.a) [forall b.b, Int] +-- This really can happen, via dressing up polymorphic types with newtype +-- clothing. Here's an example: +-- newtype R = R (forall a. a->a) +-- foo = case undefined :: R of +-- R f -> f () + +applyTys orig_fun_ty [] = orig_fun_ty +applyTys orig_fun_ty arg_tys + | n_tvs == n_args -- The vastly common case + = substTyWith tvs arg_tys rho_ty + | n_tvs > n_args -- Too many for-alls + = substTyWith (take n_args tvs) arg_tys + (mkForAllTys (drop n_args tvs) rho_ty) + | otherwise -- Too many type args + = ASSERT2( n_tvs > 0, ppr orig_fun_ty ) -- Zero case gives infnite loop! + applyTys (substTyWith tvs (take n_tvs arg_tys) rho_ty) + (drop n_tvs arg_tys) where - hoist :: Type -> ([TyVar], Type) - hoist ty = case splitFunTys ty of { (args, res) -> - case splitForAllTys res of { - ([], body) -> ([], ty) ; - (tvs1, body1) -> case hoist body1 of { (tvs2,body2) -> - (tvs1 ++ tvs2, mkFunTys args body2) - }}} + (tvs, rho_ty) = splitForAllTys orig_fun_ty + n_tvs = length tvs + n_args = length arg_tys \end{code} %************************************************************************ %* * -\subsection{Stuff to do with the source-language types} - -PredType and ThetaType are used in types for expressions and bindings. -ClassPred and ClassContext are used in class and instance declarations. +\subsection{Source types} %* * %************************************************************************ -\begin{code} -type RhoType = Type -type TauType = Type -data PredType = Class Class [Type] - | IParam Name Type -type ThetaType = [PredType] -type ClassPred = (Class, [Type]) -type ClassContext = [ClassPred] -type SigmaType = Type -\end{code} +A "source type" is a type that is a separate type as far as the type checker is +concerned, but which has low-level representation as far as the back end is concerned. -\begin{code} -instance Outputable PredType where - ppr = pprPred -\end{code} +Source types are always lifted. -\begin{code} -mkClassPred clas tys = Class clas tys - -getClassTys_maybe :: PredType -> Maybe ClassPred -getClassTys_maybe (Class clas tys) = Just (clas, tys) -getClassTys_maybe _ = Nothing - -ipName_maybe :: PredType -> Maybe Name -ipName_maybe (IParam n _) = Just n -ipName_maybe _ = Nothing - -classesToPreds cts = map (uncurry Class) cts - -classesOfPreds theta = concatMap cvt theta - where cvt (Class clas tys) = [(clas, tys)] - cvt (IParam _ _ ) = [] -\end{code} - -@isTauTy@ tests for nested for-alls. +The key function is predTypeRep which gives the representation of a source type: \begin{code} -isTauTy :: Type -> Bool -isTauTy (TyVarTy v) = True -isTauTy (TyConApp _ tys) = all isTauTy tys -isTauTy (AppTy a b) = isTauTy a && isTauTy b -isTauTy (FunTy a b) = isTauTy a && isTauTy b -isTauTy (NoteTy _ ty) = isTauTy ty -isTauTy other = False -\end{code} - -\begin{code} -mkRhoTy :: [PredType] -> Type -> Type -mkRhoTy theta ty = foldr (\p r -> FunTy (mkPredTy p) r) ty theta - -splitRhoTy :: Type -> ([PredType], Type) -splitRhoTy ty = split ty ty [] - where - split orig_ty (FunTy arg res) ts = case splitPredTy_maybe arg of - Just p -> split res res (p:ts) - Nothing -> (reverse ts, orig_ty) - split orig_ty (NoteTy _ ty) ts = split orig_ty ty ts - split orig_ty ty ts = (reverse ts, orig_ty) +mkPredTy :: PredType -> Type +mkPredTy pred = PredTy pred + +mkPredTys :: ThetaType -> [Type] +mkPredTys preds = map PredTy preds + +predTypeRep :: PredType -> Type +-- Convert a PredType to its "representation type"; +-- the post-type-checking type used by all the Core passes of GHC. +predTypeRep (IParam _ ty) = ty +predTypeRep (ClassP clas tys) = mkTyConApp (classTyCon clas) tys + -- Result might be a NewTcApp, but the consumer will + -- look through that too if necessary \end{code} +%************************************************************************ +%* * + NewTypes +%* * +%************************************************************************ \begin{code} -mkSigmaTy tyvars theta tau = mkForAllTys tyvars (mkRhoTy theta tau) - -splitSigmaTy :: Type -> ([TyVar], [PredType], Type) -splitSigmaTy ty = - (tyvars, theta, tau) - where - (tyvars,rho) = splitForAllTys ty - (theta,tau) = splitRhoTy rho +splitRecNewType_maybe :: Type -> Maybe Type +-- Newtypes are always represented by a NewTcApp +-- Sometimes we want to look through a recursive newtype, and that's what happens here +-- Only applied to types of kind *, hence the newtype is always saturated +splitRecNewType_maybe (NoteTy _ ty) = splitRecNewType_maybe ty +splitRecNewType_maybe (NewTcApp tc tys) + | isRecursiveTyCon tc + = ASSERT( tys `lengthIs` tyConArity tc && isNewTyCon tc ) + -- The assert should hold because repType should + -- only be applied to *types* (of kind *) + Just (new_type_rep tc tys) +splitRecNewType_maybe other = Nothing + +----------------------------- +newTypeRep :: TyCon -> [Type] -> Type +-- A local helper function (not exported) +-- Expands a newtype application to +-- *either* a vanilla TyConApp (recursive newtype, or non-saturated) +-- *or* the newtype representation (otherwise) +-- Either way, the result is not a NewTcApp +-- +-- NB: the returned TyConApp is always deconstructed immediately by the +-- caller... a TyConApp with a newtype type constructor never lives +-- in an ordinary type +newTypeRep tc tys + | not (isRecursiveTyCon tc), -- Not recursive and saturated + tys `lengthIs` tyConArity tc -- treat as equivalent to expansion + = new_type_rep tc tys + | otherwise + = TyConApp tc tys + -- ToDo: Consider caching this substitution in a NType + +---------------------------- +-- new_type_rep doesn't ask any questions: +-- it just expands newtype, whether recursive or not +new_type_rep new_tycon tys = ASSERT( tys `lengthIs` tyConArity new_tycon ) + case newTyConRep new_tycon of + (tvs, rep_ty) -> substTyWith tvs tys rep_ty \end{code} @@ -778,14 +580,13 @@ splitSigmaTy ty = typeKind :: Type -> Kind typeKind (TyVarTy tyvar) = tyVarKind tyvar -typeKind (TyConApp tycon tys) = foldr (\_ k -> funResultTy k) (tyConKind tycon) tys +typeKind (TyConApp tycon tys) = foldr (\_ k -> kindFunResult k) (tyConKind tycon) tys +typeKind (NewTcApp tycon tys) = foldr (\_ k -> kindFunResult k) (tyConKind tycon) tys typeKind (NoteTy _ ty) = typeKind ty -typeKind (AppTy fun arg) = funResultTy (typeKind fun) - -typeKind (FunTy arg res) = boxedTypeKind -- A function is boxed regardless of its result type - -- No functions at the type level, hence we don't need - -- to say (typeKind res). - +typeKind (PredTy _) = liftedTypeKind -- Predicates are always + -- represented by lifted types +typeKind (AppTy fun arg) = kindFunResult (typeKind fun) +typeKind (FunTy arg res) = liftedTypeKind typeKind (ForAllTy tv ty) = typeKind ty \end{code} @@ -795,51 +596,47 @@ typeKind (ForAllTy tv ty) = typeKind ty ~~~~~~~~~~~~~~~~~~~~~~~~ \begin{code} tyVarsOfType :: Type -> TyVarSet - tyVarsOfType (TyVarTy tv) = unitVarSet tv tyVarsOfType (TyConApp tycon tys) = tyVarsOfTypes tys +tyVarsOfType (NewTcApp tycon tys) = tyVarsOfTypes tys tyVarsOfType (NoteTy (FTVNote tvs) ty2) = tvs -tyVarsOfType (NoteTy (SynNote ty1) ty2) = tyVarsOfType ty1 -tyVarsOfType (NoteTy (UsgNote _) ty) = tyVarsOfType ty -tyVarsOfType (NoteTy (UsgForAll _) ty) = tyVarsOfType ty -tyVarsOfType (NoteTy (IPNote _) ty) = tyVarsOfType ty +tyVarsOfType (NoteTy (SynNote ty1) ty2) = tyVarsOfType ty2 -- See note [Syn] below +tyVarsOfType (PredTy sty) = tyVarsOfPred sty tyVarsOfType (FunTy arg res) = tyVarsOfType arg `unionVarSet` tyVarsOfType res tyVarsOfType (AppTy fun arg) = tyVarsOfType fun `unionVarSet` tyVarsOfType arg tyVarsOfType (ForAllTy tyvar ty) = tyVarsOfType ty `minusVarSet` unitVarSet tyvar +-- Note [Syn] +-- Consider +-- type T a = Int +-- What are the free tyvars of (T x)? Empty, of course! +-- Here's the example that Ralf Laemmel showed me: +-- foo :: (forall a. C u a -> C u a) -> u +-- mappend :: Monoid u => u -> u -> u +-- +-- bar :: Monoid u => u +-- bar = foo (\t -> t `mappend` t) +-- We have to generalise at the arg to f, and we don't +-- want to capture the constraint (Monad (C u a)) because +-- it appears to mention a. Pretty silly, but it was useful to him. + + tyVarsOfTypes :: [Type] -> TyVarSet tyVarsOfTypes tys = foldr (unionVarSet.tyVarsOfType) emptyVarSet tys tyVarsOfPred :: PredType -> TyVarSet -tyVarsOfPred (Class clas tys) = tyVarsOfTypes tys -tyVarsOfPred (IParam n ty) = tyVarsOfType ty +tyVarsOfPred (IParam _ ty) = tyVarsOfType ty +tyVarsOfPred (ClassP _ tys) = tyVarsOfTypes tys tyVarsOfTheta :: ThetaType -> TyVarSet tyVarsOfTheta = foldr (unionVarSet . tyVarsOfPred) emptyVarSet -- Add a Note with the free tyvars to the top of the type --- (but under a usage if there is one) addFreeTyVars :: Type -> Type -addFreeTyVars (NoteTy note@(UsgNote _) ty) = NoteTy note (addFreeTyVars ty) -addFreeTyVars (NoteTy note@(UsgForAll _) ty) = NoteTy note (addFreeTyVars ty) addFreeTyVars ty@(NoteTy (FTVNote _) _) = ty addFreeTyVars ty = NoteTy (FTVNote (tyVarsOfType ty)) ty - --- Find the free names of a type, including the type constructors and classes it mentions -namesOfType :: Type -> NameSet -namesOfType (TyVarTy tv) = unitNameSet (getName tv) -namesOfType (TyConApp tycon tys) = unitNameSet (getName tycon) `unionNameSets` - namesOfTypes tys -namesOfType (NoteTy (SynNote ty1) ty2) = namesOfType ty1 -namesOfType (NoteTy other_note ty2) = namesOfType ty2 -namesOfType (FunTy arg res) = namesOfType arg `unionNameSets` namesOfType res -namesOfType (AppTy fun arg) = namesOfType fun `unionNameSets` namesOfType arg -namesOfType (ForAllTy tyvar ty) = namesOfType ty `minusNameSet` unitNameSet (getName tyvar) - -namesOfTypes tys = foldr (unionNameSets . namesOfType) emptyNameSet tys \end{code} - %************************************************************************ %* * \subsection{TidyType} @@ -852,28 +649,33 @@ an interface file. It doesn't change the uniques at all, just the print names. \begin{code} -tidyTyVar :: TidyEnv -> TyVar -> (TidyEnv, TyVar) -tidyTyVar env@(tidy_env, subst) tyvar - = case lookupVarEnv subst tyvar of - - Just tyvar' -> -- Already substituted - (env, tyvar') - - Nothing -> -- Make a new nice name for it - - case tidyOccName tidy_env (getOccName name) of - (tidy', occ') -> -- New occname reqd - ((tidy', subst'), tyvar') - where - subst' = extendVarEnv subst tyvar tyvar' - tyvar' = setTyVarName tyvar name' - name' = mkLocalName (getUnique name) occ' noSrcLoc - -- Note: make a *user* tyvar, so it printes nicely - -- Could extract src loc, but no need. +tidyTyVarBndr :: TidyEnv -> TyVar -> (TidyEnv, TyVar) +tidyTyVarBndr (tidy_env, subst) tyvar + = case tidyOccName tidy_env (getOccName name) of + (tidy', occ') -> ((tidy', subst'), tyvar') + where + subst' = extendVarEnv subst tyvar tyvar' + tyvar' = setTyVarName tyvar name' + name' = mkInternalName (getUnique name) occ' noSrcLoc + -- Note: make a *user* tyvar, so it printes nicely + -- Could extract src loc, but no need. where name = tyVarName tyvar -tidyTyVars env tyvars = mapAccumL tidyTyVar env tyvars +tidyFreeTyVars :: TidyEnv -> TyVarSet -> TidyEnv +-- Add the free tyvars to the env in tidy form, +-- so that we can tidy the type they are free in +tidyFreeTyVars env tyvars = fst (tidyOpenTyVars env (varSetElems tyvars)) + +tidyOpenTyVars :: TidyEnv -> [TyVar] -> (TidyEnv, [TyVar]) +tidyOpenTyVars env tyvars = mapAccumL tidyOpenTyVar env tyvars + +tidyOpenTyVar :: TidyEnv -> TyVar -> (TidyEnv, TyVar) +-- Treat a new tyvar as a binder, and give it a fresh tidy name +tidyOpenTyVar env@(tidy_env, subst) tyvar + = case lookupVarEnv subst tyvar of + Just tyvar' -> (env, tyvar') -- Already substituted + Nothing -> tidyTyVarBndr env tyvar -- Treat it as a binder tidyType :: TidyEnv -> Type -> Type tidyType env@(tidy_env, subst) ty @@ -884,20 +686,24 @@ tidyType env@(tidy_env, subst) ty Just tv' -> TyVarTy tv' go (TyConApp tycon tys) = let args = map go tys in args `seqList` TyConApp tycon args - go (NoteTy note ty) = (NoteTy SAPPLY (go_note note)) SAPPLY (go ty) - go (AppTy fun arg) = (AppTy SAPPLY (go fun)) SAPPLY (go arg) - go (FunTy fun arg) = (FunTy SAPPLY (go fun)) SAPPLY (go arg) - go (ForAllTy tv ty) = ForAllTy tvp SAPPLY (tidyType envp ty) + go (NewTcApp tycon tys) = let args = map go tys + in args `seqList` NewTcApp tycon args + go (NoteTy note ty) = (NoteTy $! (go_note note)) $! (go ty) + go (PredTy sty) = PredTy (tidyPred env sty) + go (AppTy fun arg) = (AppTy $! (go fun)) $! (go arg) + go (FunTy fun arg) = (FunTy $! (go fun)) $! (go arg) + go (ForAllTy tv ty) = ForAllTy tvp $! (tidyType envp ty) where - (envp, tvp) = tidyTyVar env tv + (envp, tvp) = tidyTyVarBndr env tv - go_note (SynNote ty) = SynNote SAPPLY (go ty) + go_note (SynNote ty) = SynNote $! (go ty) go_note note@(FTVNote ftvs) = note -- No need to tidy the free tyvars - go_note note@(UsgNote _) = note -- Usage annotation is already tidy - go_note note@(UsgForAll _) = note -- Uvar binder is already tidy - go_note (IPNote n) = IPNote (tidyIPName n) -tidyTypes env tys = map (tidyType env) tys +tidyTypes env tys = map (tidyType env) tys + +tidyPred :: TidyEnv -> PredType -> PredType +tidyPred env (IParam n ty) = IParam n (tidyType env ty) +tidyPred env (ClassP clas tys) = ClassP clas (tidyTypes env tys) \end{code} @@ -909,8 +715,7 @@ tidyOpenType :: TidyEnv -> Type -> (TidyEnv, Type) tidyOpenType env ty = (env', tidyType env' ty) where - env' = foldl go env (varSetElems (tyVarsOfType ty)) - go env tyvar = fst (tidyTyVar env tyvar) + env' = tidyFreeTyVars env (tyVarsOfType ty) tidyOpenTypes :: TidyEnv -> [Type] -> (TidyEnv, [Type]) tidyOpenTypes env tys = mapAccumL tidyOpenType env tys @@ -919,23 +724,15 @@ tidyTopType :: Type -> Type tidyTopType ty = tidyType emptyTidyEnv ty \end{code} -\begin{code} -tidyIPName :: Name -> Name -tidyIPName name - = mkLocalName (getUnique name) (getOccName name) noSrcLoc -\end{code} %************************************************************************ %* * -\subsection{Boxedness and liftedness} +\subsection{Liftedness} %* * %************************************************************************ \begin{code} -isUnboxedType :: Type -> Bool -isUnboxedType ty = not (isFollowableRep (typePrimRep ty)) - isUnLiftedType :: Type -> Bool -- isUnLiftedType returns True for forall'd unlifted types: -- x :: forall a. Int# @@ -943,10 +740,12 @@ isUnLiftedType :: Type -> Bool -- They are pretty bogus types, mind you. It would be better never to -- construct them -isUnLiftedType (ForAllTy tv ty) = isUnLiftedType ty -isUnLiftedType (NoteTy _ ty) = isUnLiftedType ty -isUnLiftedType (TyConApp tc _) = isUnLiftedTyCon tc -isUnLiftedType other = False +isUnLiftedType (ForAllTy tv ty) = isUnLiftedType ty +isUnLiftedType (NoteTy _ ty) = isUnLiftedType ty +isUnLiftedType (TyConApp tc _) = isUnLiftedTyCon tc +isUnLiftedType (PredTy _) = False -- All source types are lifted +isUnLiftedType (NewTcApp tc tys) = isUnLiftedType (newTypeRep tc tys) +isUnLiftedType other = False isUnboxedTupleType :: Type -> Bool isUnboxedTupleType ty = case splitTyConApp_maybe ty of @@ -956,21 +755,42 @@ isUnboxedTupleType ty = case splitTyConApp_maybe ty of -- Should only be applied to *types*; hence the assert isAlgType :: Type -> Bool isAlgType ty = case splitTyConApp_maybe ty of - Just (tc, ty_args) -> ASSERT( length ty_args == tyConArity tc ) + Just (tc, ty_args) -> ASSERT( ty_args `lengthIs` tyConArity tc ) isAlgTyCon tc other -> False +\end{code} --- Should only be applied to *types*; hence the assert -isDataType :: Type -> Bool -isDataType ty = case splitTyConApp_maybe ty of - Just (tc, ty_args) -> ASSERT( length ty_args == tyConArity tc ) - isDataTyCon tc - other -> False +@isStrictType@ computes whether an argument (or let RHS) should +be computed strictly or lazily, based only on its type. +Works just like isUnLiftedType, except that it has a special case +for dictionaries. Since it takes account of ClassP, you might think +this function should be in TcType, but isStrictType is used by DataCon, +which is below TcType in the hierarchy, so it's convenient to put it here. + +\begin{code} +isStrictType (ForAllTy tv ty) = isStrictType ty +isStrictType (NoteTy _ ty) = isStrictType ty +isStrictType (TyConApp tc _) = isUnLiftedTyCon tc +isStrictType (NewTcApp tc tys) = isStrictType (newTypeRep tc tys) +isStrictType (PredTy pred) = isStrictPred pred +isStrictType other = False + +isStrictPred (ClassP clas _) = opt_DictsStrict && not (isNewTyCon (classTyCon clas)) +isStrictPred other = False + -- We may be strict in dictionary types, but only if it + -- has more than one component. + -- [Being strict in a single-component dictionary risks + -- poking the dictionary component, which is wrong.] +\end{code} -isNewType :: Type -> Bool -isNewType ty = case splitTyConApp_maybe ty of - Just (tc, ty_args) -> ASSERT( length ty_args == tyConArity tc ) - isNewTyCon tc +\begin{code} +isPrimitiveType :: Type -> Bool +-- Returns types that are opaque to Haskell. +-- Most of these are unlifted, but now that we interact with .NET, we +-- may have primtive (foreign-imported) types that are lifted +isPrimitiveType ty = case splitTyConApp_maybe ty of + Just (tc, ty_args) -> ASSERT( ty_args `lengthIs` tyConArity tc ) + isPrimTyCon tc other -> False \end{code} @@ -987,7 +807,9 @@ seqType (TyVarTy tv) = tv `seq` () seqType (AppTy t1 t2) = seqType t1 `seq` seqType t2 seqType (FunTy t1 t2) = seqType t1 `seq` seqType t2 seqType (NoteTy note t2) = seqNote note `seq` seqType t2 +seqType (PredTy p) = seqPred p seqType (TyConApp tc tys) = tc `seq` seqTypes tys +seqType (NewTcApp tc tys) = tc `seq` seqTypes tys seqType (ForAllTy tv ty) = tv `seq` seqType ty seqTypes :: [Type] -> () @@ -997,7 +819,79 @@ seqTypes (ty:tys) = seqType ty `seq` seqTypes tys seqNote :: TyNote -> () seqNote (SynNote ty) = seqType ty seqNote (FTVNote set) = sizeUniqSet set `seq` () -seqNote (UsgNote usg) = usg `seq` () -seqNote (IPNote nm) = nm `seq` () + +seqPred :: PredType -> () +seqPred (ClassP c tys) = c `seq` seqTypes tys +seqPred (IParam n ty) = n `seq` seqType ty +\end{code} + + +%************************************************************************ +%* * +\subsection{Equality on types} +%* * +%************************************************************************ + +Comparison; don't use instances so that we know where it happens. +Look through newtypes but not usage types. + +Note that eqType can respond 'False' for partial applications of newtypes. +Consider + newtype Parser m a = MkParser (Foogle m a) + +Does + Monad (Parser m) `eqType` Monad (Foogle m) + +Well, yes, but eqType won't see that they are the same. +I don't think this is harmful, but it's soemthing to watch out for. + +\begin{code} +eqType t1 t2 = eq_ty emptyVarEnv t1 t2 + +-- Look through Notes +eq_ty env (NoteTy _ t1) t2 = eq_ty env t1 t2 +eq_ty env t1 (NoteTy _ t2) = eq_ty env t1 t2 + +-- Look through PredTy and NewTcApp. This is where the looping danger comes from. +-- We don't bother to check for the PredType/PredType case, no good reason +-- Hmm: maybe there is a good reason: see the notes below about newtypes +eq_ty env (PredTy sty1) t2 = eq_ty env (predTypeRep sty1) t2 +eq_ty env t1 (PredTy sty2) = eq_ty env t1 (predTypeRep sty2) + +-- NB: we *cannot* short-cut the newtype comparison thus: +-- eq_ty env (NewTcApp tc1 tys1) (NewTcApp tc2 tys2) +-- | (tc1 == tc2) = (eq_tys env tys1 tys2) +-- +-- Consider: +-- newtype T a = MkT [a] +-- newtype Foo m = MkFoo (forall a. m a -> Int) +-- w1 :: Foo [] +-- w1 = ... +-- +-- w2 :: Foo T +-- w2 = MkFoo (\(MkT x) -> case w1 of MkFoo f -> f x) +-- +-- We end up with w2 = w1; so we need that Foo T = Foo [] +-- but we can only expand saturated newtypes, so just comparing +-- T with [] won't do. + +eq_ty env (NewTcApp tc1 tys1) t2 = eq_ty env (newTypeRep tc1 tys1) t2 +eq_ty env t1 (NewTcApp tc2 tys2) = eq_ty env t1 (newTypeRep tc2 tys2) + +-- The rest is plain sailing +eq_ty env (TyVarTy tv1) (TyVarTy tv2) = case lookupVarEnv env tv1 of + Just tv1a -> tv1a == tv2 + Nothing -> tv1 == tv2 +eq_ty env (ForAllTy tv1 t1) (ForAllTy tv2 t2) + | tv1 == tv2 = eq_ty (delVarEnv env tv1) t1 t2 + | otherwise = eq_ty (extendVarEnv env tv1 tv2) t1 t2 +eq_ty env (AppTy s1 t1) (AppTy s2 t2) = (eq_ty env s1 s2) && (eq_ty env t1 t2) +eq_ty env (FunTy s1 t1) (FunTy s2 t2) = (eq_ty env s1 s2) && (eq_ty env t1 t2) +eq_ty env (TyConApp tc1 tys1) (TyConApp tc2 tys2) = (tc1 == tc2) && (eq_tys env tys1 tys2) +eq_ty env t1 t2 = False + +eq_tys env [] [] = True +eq_tys env (t1:tys1) (t2:tys2) = (eq_ty env t1 t2) && (eq_tys env tys1 tys2) +eq_tys env tys1 tys2 = False \end{code}