X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypes%2FType.lhs;h=c7e5fa250901254842eab866d7a2e7d0edde5851;hb=423d477bfecd490de1449c59325c8776f91d7aac;hp=e139cddda7a840e8f76e7221680cf600a559c98a;hpb=0710d446789cc7b3e29f12ab56d9d5315fd4b8af;p=ghc-hetmet.git diff --git a/ghc/compiler/types/Type.lhs b/ghc/compiler/types/Type.lhs index e139cdd..c7e5fa2 100644 --- a/ghc/compiler/types/Type.lhs +++ b/ghc/compiler/types/Type.lhs @@ -1,310 +1,106 @@ +% +% (c) The GRASP/AQUA Project, Glasgow University, 1998 +% +\section[Type]{Type - public interface} + \begin{code} module Type ( - Type(..), TyNote(..), -- Representation visible to friends - Kind, TyVarSubst, - - superKind, superBoxity, -- :: SuperKind - - boxedKind, -- :: Kind :: BX - anyBoxKind, -- :: Kind :: BX - typeCon, -- :: KindCon :: BX -> KX - anyBoxCon, -- :: KindCon :: BX - - boxedTypeKind, unboxedTypeKind, openTypeKind, -- Kind :: superKind + -- re-exports from TypeRep + TyThing(..), Type, PredType(..), ThetaType, TyVarSubst, + funTyCon, - mkArrowKind, mkArrowKinds, hasMoreBoxityInfo, + -- Re-exports from Kind + module Kind, - funTyCon, + -- Re-exports from TyCon + PrimRep(..), mkTyVarTy, mkTyVarTys, getTyVar, getTyVar_maybe, isTyVarTy, mkAppTy, mkAppTys, splitAppTy, splitAppTys, splitAppTy_maybe, - mkFunTy, mkFunTys, splitFunTy_maybe, splitFunTys, funResultTy, - zipFunTys, + mkFunTy, mkFunTys, splitFunTy, splitFunTy_maybe, splitFunTys, + funResultTy, funArgTy, zipFunTys, isFunTy, + + mkGenTyConApp, mkTyConApp, mkTyConTy, + tyConAppTyCon, tyConAppArgs, + splitTyConApp_maybe, splitTyConApp, - mkTyConApp, mkTyConTy, splitTyConApp_maybe, - splitAlgTyConApp_maybe, splitAlgTyConApp, - mkDictTy, splitDictTy_maybe, isDictTy, + mkSynTy, - mkSynTy, isSynTy, deNoteType, + repType, typePrimRep, mkForAllTy, mkForAllTys, splitForAllTy_maybe, splitForAllTys, - applyTy, applyTys, isForAllTy, - mkPiType, + applyTy, applyTys, isForAllTy, dropForAlls, - TauType, RhoType, SigmaType, ThetaType, - isTauTy, - mkRhoTy, splitRhoTy, - mkSigmaTy, splitSigmaTy, + -- Source types + predTypeRep, mkPredTy, mkPredTys, + + -- Newtypes + splitRecNewType_maybe, -- Lifting and boxity - isUnLiftedType, isUnboxedType, isUnboxedTupleType, isAlgType, isDataType, - typePrimRep, + isUnLiftedType, isUnboxedTupleType, isAlgType, isPrimitiveType, + isStrictType, isStrictPred, -- Free variables - tyVarsOfType, tyVarsOfTypes, namesOfType, typeKind, - addFreeTyVars, - - -- Substitution - substTy, substTheta, fullSubstTy, substTyVar, - substTopTy, substTopTheta, + tyVarsOfType, tyVarsOfTypes, tyVarsOfPred, tyVarsOfTheta, + 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, + + -- Pretty-printing + pprType, pprParendType, + pprPred, pprTheta, pprThetaArrow, pprClassPred ) where #include "HsVersions.h" -import {-# SOURCE #-} DataCon( DataCon ) -import {-# SOURCE #-} PprType( pprType ) -- Only called in debug messages +-- We import the representation and primitive functions from TypeRep. +-- Many things are reexported, but not the representation! + +import TypeRep + +-- Other imports: + +import {-# SOURCE #-} Subst ( substTyWith ) -- friends: -import Var ( Id, TyVar, IdOrTyVar, - tyVarKind, tyVarName, isId, idType, setTyVarName - ) +import Kind +import Var ( TyVar, tyVarKind, tyVarName, setTyVarName ) import VarEnv import VarSet -import Name ( NamedThing(..), Provenance(..), ExportFlag(..), - mkWiredInTyConName, mkGlobalName, mkLocalName, mkKindOccFS, tcName, - tidyOccName, TidyOccEnv - ) -import NameSet -import Class ( classTyCon, Class ) -import TyCon ( TyCon, KindCon, - mkFunTyCon, mkKindCon, mkSuperKindCon, - matchesTyCon, isUnboxedTupleTyCon, isUnLiftedTyCon, - isFunTyCon, isDataTyCon, - isAlgTyCon, isSynTyCon, tyConArity, - tyConKind, tyConDataCons, getSynTyConDefn, - tyConPrimRep, tyConClass_maybe +import Name ( NamedThing(..), mkInternalName, tidyOccName ) +import Class ( Class, classTyCon ) +import TyCon ( TyCon, isRecursiveTyCon, isPrimTyCon, + isUnboxedTupleTyCon, isUnLiftedTyCon, + isFunTyCon, isNewTyCon, newTyConRep, newTyConRhs, + isAlgTyCon, isSynTyCon, tyConArity, + tyConKind, getSynTyConDefn, PrimRep(..), tyConPrimRep, ) -- others -import BasicTypes ( Unused ) -import SrcLoc ( mkBuiltinSrcLoc, noSrcLoc ) -import PrelMods ( pREL_GHC ) -import Maybes ( maybeToBool ) -import PrimRep ( PrimRep(..), isFollowableRep ) -import Unique -- quite a few *Keys -import Util ( thenCmp, mapAccumL, seqList, ($!) ) +import CmdLineOpts ( opt_DictsStrict ) +import SrcLoc ( noSrcLoc ) +import Unique ( Uniquable(..) ) +import Util ( mapAccumL, seqList, lengthIs, snocView ) import Outputable - -\end{code} - -%************************************************************************ -%* * -\subsection{Type Classifications} -%* * -%************************************************************************ - -A type is - - *unboxed* iff its representation is other than a pointer - Unboxed types cannot instantiate a type variable. - Unboxed types are always unlifted. - - *lifted* A type is lifted iff it has bottom as an element. - Closures always have lifted types: i.e. any - let-bound identifier in Core must have a lifted - type. Operationally, a lifted object is one that - can be entered. - (NOTE: previously "pointed"). - - *algebraic* A type with one or more constructors, whether declared - with "data" or "newtype". - An algebraic type is one that can be deconstructed - with a case expression. - - *NOT* the same as lifted types, because we also - include unboxed tuples in this classification. - - *data* A type declared with "data". Also boxed tuples. - - *primitive* iff it is a built-in type that can't be expressed - in Haskell. - -Currently, all primitive types are unlifted, but that's not necessarily -the case. (E.g. Int could be primitive.) - -Some primitive types are unboxed, such as Int#, whereas some are boxed -but unlifted (such as ByteArray#). The only primitive types that we -classify as algebraic are the unboxed tuples. - -examples of type classifications: - -Type primitive boxed lifted algebraic ------------------------------------------------------------------------------ -Int#, Yes No No No -ByteArray# Yes Yes No No -(# a, b #) Yes No No Yes -( a, b ) No Yes Yes Yes -[a] No Yes Yes Yes - -%************************************************************************ -%* * -\subsection{The data type} -%* * -%************************************************************************ - - -\begin{code} -type SuperKind = Type -type Kind = Type - -type TyVarSubst = TyVarEnv Type - -data Type - = TyVarTy TyVar - - | AppTy - Type -- Function is *not* a TyConApp - Type - - | TyConApp -- Application of a TyCon - TyCon -- *Invariant* saturated appliations of FunTyCon and - -- synonyms have their own constructors, below. - [Type] -- Might not be saturated. - - | FunTy -- Special case of TyConApp: TyConApp FunTyCon [t1,t2] - Type - Type - - | NoteTy -- Saturated application of a type synonym - TyNote - Type -- The expanded version - - | ForAllTy - TyVar - Type -- TypeKind - -data TyNote - = SynNote Type -- The unexpanded version of the type synonym; always a TyConApp - | FTVNote TyVarSet -- The free type variables of the noted expression -\end{code} - - -%************************************************************************ -%* * -\subsection{Kinds} -%* * -%************************************************************************ - -Kinds -~~~~~ -k::K = Type bx - | k -> k - | kv - -kv :: KX is a kind variable - -Type :: BX -> KX - -bx::BX = Boxed - | Unboxed - | AnyBox -- Used *only* for special built-in things - -- like error :: forall (a::*?). String -> a - -- Here, the 'a' can be instantiated to a boxed or - -- unboxed type. - | bv - -bxv :: BX is a boxity variable - -sk = KX -- A kind - | BX -- A boxity - | sk -> sk -- In ptic (BX -> KX) - -\begin{code} -mk_kind_name key str = mkGlobalName key pREL_GHC (mkKindOccFS tcName str) - (LocalDef mkBuiltinSrcLoc NotExported) - -- mk_kind_name is a bit of a hack - -- The LocalDef means that we print the name without - -- a qualifier, which is what we want for these kinds. - -- It's used for both Kinds and Boxities +import UniqSet ( sizeUniqSet ) -- Should come via VarSet +import Maybe ( isJust ) \end{code} -Define KX, BX. - -\begin{code} -superKind :: SuperKind -- KX, the type of all kinds -superKindName = mk_kind_name kindConKey SLIT("KX") -superKind = TyConApp (mkSuperKindCon superKindName) [] - -superBoxity :: SuperKind -- BX, the type of all boxities -superBoxityName = mk_kind_name boxityConKey SLIT("BX") -superBoxity = TyConApp (mkSuperKindCon superBoxityName) [] -\end{code} - -Define Boxed, Unboxed, AnyBox - -\begin{code} -boxedKind, unboxedKind, anyBoxKind :: Kind -- Of superkind superBoxity - -boxedConName = mk_kind_name boxedConKey SLIT("*") -boxedKind = TyConApp (mkKindCon boxedConName superBoxity) [] - -unboxedConName = mk_kind_name unboxedConKey SLIT("#") -unboxedKind = TyConApp (mkKindCon unboxedConName superBoxity) [] - -anyBoxConName = mk_kind_name anyBoxConKey SLIT("?") -anyBoxCon = mkKindCon anyBoxConName superBoxity -- A kind of wild card -anyBoxKind = TyConApp anyBoxCon [] -\end{code} - -Define Type - -\begin{code} -typeCon :: KindCon -typeConName = mk_kind_name typeConKey SLIT("Type") -typeCon = mkKindCon typeConName (superBoxity `FunTy` superKind) -\end{code} - -Define (Type Boxed), (Type Unboxed), (Type AnyBox) - -\begin{code} -boxedTypeKind, unboxedTypeKind, openTypeKind :: Kind -boxedTypeKind = TyConApp typeCon [boxedKind] -unboxedTypeKind = TyConApp typeCon [unboxedKind] -openTypeKind = TyConApp typeCon [anyBoxKind] - -mkArrowKind :: Kind -> Kind -> Kind -mkArrowKind k1 k2 = k1 `FunTy` k2 - -mkArrowKinds :: [Kind] -> Kind -> Kind -mkArrowKinds arg_kinds result_kind = foldr mkArrowKind result_kind arg_kinds -\end{code} - -\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 -\end{code} - - -%************************************************************************ -%* * -\subsection{Wired-in type constructors -%* * -%************************************************************************ - -We define a few wired-in type constructors here to avoid module knots - -\begin{code} -funTyConName = mkWiredInTyConName funTyConKey pREL_GHC SLIT("(->)") funTyCon -funTyCon = mkFunTyCon funTyConName (mkArrowKinds [boxedTypeKind, boxedTypeKind] boxedTypeKind) -\end{code} - - %************************************************************************ %* * @@ -324,19 +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} @@ -348,36 +144,50 @@ invariant that a TyConApp is always visibly so. mkAppTy maintains the invariant: use it. \begin{code} -mkAppTy orig_ty1 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 = 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) + -- 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 @@ -389,9 +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} @@ -407,109 +220,108 @@ mkFunTy arg res = FunTy arg res mkFunTys :: [Type] -> Type -> Type mkFunTys tys ty = foldr FunTy ty tys -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 +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 (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 (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) + 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 (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 - -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 - -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} @@ -518,24 +330,29 @@ isDictTy other = False ~~~~~ \begin{code} -mkSynTy syn_tycon tys - = ASSERT(isSynTyCon syn_tycon) - NoteTy (SynNote (TyConApp syn_tycon tys)) - (substTopTy (zipVarEnv 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 @@ -553,6 +370,48 @@ The reason is that we then get better (shorter) type signatures in interfaces. Notably this plays a role in tcTySigs in TcBinds.lhs. + Representation types + ~~~~~~~~~~~~~~~~~~~~ +repType looks through + (a) for-alls, and + (b) synonyms + (c) predicates + (d) usage annotations + (e) [recursive] newtypes +It's useful in the back end. + +\begin{code} +repType :: Type -> Type +-- 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 + + +-- ToDo: this could be moved to the code generator, using splitTyConApp instead +-- of inspecting the type directly. +typePrimRep :: Type -> PrimRep +typePrimRep ty = case repType ty of + TyConApp tc _ -> tyConPrimRep tc + FunTy _ _ -> PtrRep + AppTy _ _ -> PtrRep -- See note below + TyVarTy _ -> PtrRep + other -> pprPanic "typePrimRep" (ppr ty) + -- Types of the form 'f a' must be of kind *, not *#, so + -- we are guaranteed that they are represented by pointers. + -- The reason is that f must have kind *->*, not *->*#, because + -- (we claim) there is no way to constrain f's kind any other + -- way. + +-- 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} --------------------------------------------------------------------- @@ -560,105 +419,174 @@ interfaces. Notably this plays a role in tcTySigs in TcBinds.lhs. ~~~~~~~~ \begin{code} -mkForAllTy = ForAllTy +mkForAllTy :: TyVar -> Type -> Type +mkForAllTy tyvar ty + = mkForAllTys [tyvar] ty mkForAllTys :: [TyVar] -> Type -> Type mkForAllTys tyvars ty = foldr ForAllTy ty tyvars -splitForAllTy_maybe :: Type -> Maybe (TyVar, Type) -splitForAllTy_maybe (NoteTy _ ty) = splitForAllTy_maybe ty -splitForAllTy_maybe (ForAllTy tyvar ty) = Just(tyvar, ty) -splitForAllTy_maybe _ = Nothing - isForAllTy :: Type -> Bool -isForAllTy (NoteTy _ ty) = isForAllTy ty -isForAllTy (ForAllTy tyvar ty) = True -isForAllTy _ = False +isForAllTy (NoteTy _ ty) = isForAllTy ty +isForAllTy (ForAllTy _ _) = True +isForAllTy other_ty = False + +splitForAllTy_maybe :: Type -> Maybe (TyVar, Type) +splitForAllTy_maybe ty = splitFAT_m ty + where + 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 = 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. +-- (mkPiType now in CoreUtils) -\begin{code} -mkPiType :: IdOrTyVar -> Type -> Type -- The more polymorphic version doesn't work... -mkPiType v ty | isId v = mkFunTy (idType v) ty - | otherwise = ForAllTy v ty -\end{code} +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 _ fun) arg = applyTy fun arg -applyTy (ForAllTy tv ty) arg = substTy (mkVarEnv [(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 - = go [] fun_ty arg_tys - where - go env ty [] = substTy (mkVarEnv env) ty - go env (NoteTy _ fun) args = go env fun args - go env (ForAllTy tv ty) (arg:args) = go ((tv,arg):env) ty args - go env other args = panic "applyTys" +-- 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 + (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} +\subsection{Source types} %* * %************************************************************************ -\begin{code} -type RhoType = Type -type TauType = Type -type ThetaType = [(Class, [Type])] -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. -@isTauTy@ tests for nested for-alls. +Source types are always lifted. -\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} +The key function is predTypeRep which gives the representation of a source type: \begin{code} -mkRhoTy :: [(Class, [Type])] -> Type -> Type -mkRhoTy theta ty = foldr (\(c,t) r -> FunTy (mkDictTy c t) r) ty theta - -splitRhoTy :: Type -> ([(Class, [Type])], Type) -splitRhoTy ty = split ty ty [] - where - split orig_ty (FunTy arg res) ts = case splitDictTy_maybe arg of - Just pair -> split res res (pair: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. +-- Unwraps only the outermost level; for example, the result might +-- be a NewTcApp; c.f. newTypeRep +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], [(Class, [Type])], 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 +-- It only strips *one layer* off, so the caller will usually call itself recursively +-- Only applied to types of kind *, hence the newtype is always saturated +splitRecNewType_maybe (NoteTy _ ty) = splitRecNewType_maybe ty +splitRecNewType_maybe (PredTy p) = splitRecNewType_maybe (predTypeRep p) +splitRecNewType_maybe (NewTcApp tc tys) + | isRecursiveTyCon tc + = ASSERT( tys `lengthIs` tyConArity tc && isNewTyCon tc ) + -- The assert should hold because splitRecNewType_maybe + -- should only be applied to *types* (of kind *) + Just (new_type_rhs tc tys) +splitRecNewType_maybe other = Nothing + +----------------------------- +newTypeRep :: TyCon -> [Type] -> Type +-- A local helper function (not exported) +-- Expands *the outermoset level of* a newtype application to +-- *either* a vanilla TyConApp (recursive newtype, or non-saturated) +-- *or* the newtype representation (otherwise), meaning the +-- type written in the RHS of the newtype decl, +-- which may itself be a newtype +-- +-- Example: newtype R = MkR S +-- newtype S = MkS T +-- newtype T = MkT (T -> T) +-- newTypeRep on R gives NewTcApp S +-- on S gives NewTcApp T +-- on T gives TyConApp T +-- +-- 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_rhs tc tys + | otherwise + = TyConApp tc tys + -- ToDo: Consider caching this substitution in a NType + +-- new_type_rhs doesn't ask any questions: +-- it just expands newtype one level, whether recursive or not +new_type_rhs tc tys + = case newTyConRhs tc of + (tvs, rep_ty) -> substTyWith tvs tys rep_ty \end{code} @@ -675,28 +603,14 @@ 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 fun arg) = typeKindF arg -typeKind (ForAllTy _ ty) = typeKindF ty -- We could make this a new kind polyTypeKind - -- to prevent a forall type unifying with a - -- boxed type variable, but I didn't think it - -- was worth it yet. - --- The complication is that a *function* is boxed even if --- its *result* type is unboxed. Seems wierd. - -typeKindF :: Type -> Kind -typeKindF (NoteTy _ ty) = typeKindF ty -typeKindF (FunTy _ ty) = typeKindF ty -typeKindF (ForAllTy _ ty) = typeKindF ty -typeKindF other = fix_up (typeKind other) - where - fix_up (TyConApp kc _) | kc == typeCon = boxedTypeKind - -- Functions at the type level are always boxed - fix_up (NoteTy _ kind) = fix_up kind - fix_up kind = kind +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} @@ -705,123 +619,47 @@ typeKindF other = fix_up (typeKind other) ~~~~~~~~~~~~~~~~~~~~~~~~ \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 (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 -tyVarsOfTypes :: [Type] -> TyVarSet -tyVarsOfTypes tys = foldr (unionVarSet.tyVarsOfType) emptyVarSet tys +-- 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. --- Add a Note with the free tyvars to the top of the type -addFreeTyVars :: Type -> Type -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{Instantiating a type} -%* * -%************************************************************************ -@substTy@ applies a substitution to a type. It deals correctly with name capture. +tyVarsOfTypes :: [Type] -> TyVarSet +tyVarsOfTypes tys = foldr (unionVarSet.tyVarsOfType) emptyVarSet tys -\begin{code} -substTy :: TyVarSubst -> Type -> Type -substTy tenv ty - | isEmptyVarEnv tenv = ty - | otherwise = subst_ty tenv tset ty - where - tset = foldVarEnv (unionVarSet . tyVarsOfType) emptyVarSet tenv - -- If ty doesn't have any for-alls, then this thunk - -- will never be evaluated - -substTheta :: TyVarSubst -> ThetaType -> ThetaType -substTheta tenv theta - | isEmptyVarEnv tenv = theta - | otherwise = [(clas, map (subst_ty tenv tset) tys) | (clas, tys) <- theta] - where - tset = foldVarEnv (unionVarSet . tyVarsOfType) emptyVarSet tenv - -- If ty doesn't have any for-alls, then this thunk - -- will never be evaluated - -substTopTy :: TyVarSubst -> Type -> Type -substTopTy = substTy -- Called when doing top-level substitutions. - -- Here we expect that the free vars of the range of the - -- substitution will be empty; but during typechecking I'm - -- a bit dubious about that (mutable tyvars bouund to Int, say) - -- So I've left it as substTy for the moment. SLPJ Nov 98 -substTopTheta = substTheta -\end{code} +tyVarsOfPred :: PredType -> TyVarSet +tyVarsOfPred (IParam _ ty) = tyVarsOfType ty +tyVarsOfPred (ClassP _ tys) = tyVarsOfTypes tys -@fullSubstTy@ is like @substTy@ except that it needs to be given a set -of in-scope type variables. In exchange it's a bit more efficient, at least -if you happen to have that set lying around. +tyVarsOfTheta :: ThetaType -> TyVarSet +tyVarsOfTheta = foldr (unionVarSet . tyVarsOfPred) emptyVarSet -\begin{code} -fullSubstTy :: TyVarSubst -- Substitution to apply - -> TyVarSet -- Superset of the free tyvars of - -- the range of the tyvar env - -> Type -> Type --- ASSUMPTION: The substitution is idempotent. --- Equivalently: No tyvar is both in scope, and in the domain of the substitution. -fullSubstTy tenv tset ty | isEmptyVarEnv tenv = ty - | otherwise = subst_ty tenv tset ty - --- subst_ty does the business -subst_ty tenv tset ty - = go ty - where - go (TyConApp tc tys) = let args = map go tys - in args `seqList` TyConApp tc args - go (NoteTy (SynNote ty1) ty2) = NoteTy (SynNote $! (go ty1)) $! (go ty2) - go (NoteTy (FTVNote _) ty2) = go ty2 -- Discard the free tyvar note - go (FunTy arg res) = (FunTy $! (go arg)) $! (go res) - go (AppTy fun arg) = mkAppTy (go fun) $! (go arg) - go ty@(TyVarTy tv) = case (lookupVarEnv tenv tv) of - Nothing -> ty - Just ty' -> ty' - go (ForAllTy tv ty) = case substTyVar tenv tset tv of - (tenv', tset', tv') -> ForAllTy tv' $! (subst_ty tenv' tset' ty) - -substTyVar :: TyVarSubst -> TyVarSet -> TyVar - -> (TyVarSubst, TyVarSet, TyVar) - -substTyVar tenv tset tv - | not (tv `elemVarSet` tset) -- No need to clone - -- But must delete from substitution - = (tenv `delVarEnv` tv, tset `extendVarSet` tv, tv) - - | otherwise -- The forall's variable is in scope so - -- we'd better rename it away from the in-scope variables - -- Extending the substitution to do this renaming also - -- has the (correct) effect of discarding any existing - -- substitution for that variable - = (extendVarEnv tenv tv (TyVarTy tv'), tset `extendVarSet` tv', tv') - where - tv' = uniqAway tset tv +-- Add a Note with the free tyvars to the top of the type +addFreeTyVars :: Type -> Type +addFreeTyVars ty@(NoteTy (FTVNote _) _) = ty +addFreeTyVars ty = NoteTy (FTVNote (tyVarsOfType ty)) ty \end{code} - %************************************************************************ %* * \subsection{TidyType} @@ -834,28 +672,33 @@ 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 @@ -866,21 +709,28 @@ 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 (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 tv' $! (tidyType env' ty) - where - (env', tv') = tidyTyVar env tv + go (ForAllTy tv ty) = ForAllTy tvp $! (tidyType envp ty) + where + (envp, tvp) = tidyTyVarBndr env tv go_note (SynNote ty) = SynNote $! (go ty) go_note note@(FTVNote ftvs) = note -- No need to tidy the free tyvars -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} -@tidyOpenType@ grabs the free type varibles, tidies them +@tidyOpenType@ grabs the free type variables, tidies them and then uses @tidyType@ to work over the type itself \begin{code} @@ -888,8 +738,7 @@ 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 @@ -899,20 +748,27 @@ tidyTopType ty = tidyType emptyTidyEnv ty \end{code} + %************************************************************************ %* * -\subsection{Boxedness and liftedness} +\subsection{Liftedness} %* * %************************************************************************ \begin{code} -isUnboxedType :: Type -> Bool -isUnboxedType ty = not (isFollowableRep (typePrimRep ty)) - isUnLiftedType :: Type -> Bool -isUnLiftedType ty = case splitTyConApp_maybe ty of - Just (tc, ty_args) -> isUnLiftedTyCon tc - other -> False + -- isUnLiftedType returns True for forall'd unlifted types: + -- x :: forall a. Int# + -- I found bindings like these were getting floated to the top level. + -- 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 (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 @@ -922,79 +778,143 @@ 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 +@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} + +\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} -typePrimRep :: Type -> PrimRep -typePrimRep ty = case splitTyConApp_maybe ty of - Just (tc, ty_args) -> tyConPrimRep tc - other -> PtrRep + +%************************************************************************ +%* * +\subsection{Sequencing on types +%* * +%************************************************************************ + +\begin{code} +seqType :: Type -> () +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] -> () +seqTypes [] = () +seqTypes (ty:tys) = seqType ty `seq` seqTypes tys + +seqNote :: TyNote -> () +seqNote (SynNote ty) = seqType ty +seqNote (FTVNote set) = sizeUniqSet set `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} %* * %************************************************************************ -For the moment at least, type comparisons don't work if -there are embedded for-alls. +Comparison; don't use instances so that we know where it happens. +Look through newtypes but not usage types. -\begin{code} -instance Eq Type where - ty1 == ty2 = case ty1 `cmpTy` ty2 of { EQ -> True; other -> False } +Note that eqType can respond 'False' for partial applications of newtypes. +Consider + newtype Parser m a = MkParser (Foogle m a) -instance Ord Type where - compare ty1 ty2 = cmpTy ty1 ty2 +Does + Monad (Parser m) `eqType` Monad (Foogle m) -cmpTy :: Type -> Type -> Ordering -cmpTy ty1 ty2 - = cmp emptyVarEnv ty1 ty2 - where - -- The "env" maps type variables in ty1 to type variables in ty2 - -- So when comparing for-alls.. (forall tv1 . t1) (forall tv2 . t2) - -- we in effect substitute tv2 for tv1 in t1 before continuing - lookup env tv1 = case lookupVarEnv env tv1 of - Just tv2 -> tv2 - Nothing -> tv1 - - -- Get rid of NoteTy - cmp env (NoteTy _ ty1) ty2 = cmp env ty1 ty2 - cmp env ty1 (NoteTy _ ty2) = cmp env ty1 ty2 - - -- Deal with equal constructors - cmp env (TyVarTy tv1) (TyVarTy tv2) = lookup env tv1 `compare` tv2 - cmp env (AppTy f1 a1) (AppTy f2 a2) = cmp env f1 f2 `thenCmp` cmp env a1 a2 - cmp env (FunTy f1 a1) (FunTy f2 a2) = cmp env f1 f2 `thenCmp` cmp env a1 a2 - cmp env (TyConApp tc1 tys1) (TyConApp tc2 tys2) = (tc1 `compare` tc2) `thenCmp` (cmps env tys1 tys2) - cmp env (ForAllTy tv1 t1) (ForAllTy tv2 t2) = cmp (extendVarEnv env tv1 tv2) t1 t2 - - -- Deal with the rest: TyVarTy < AppTy < FunTy < TyConApp < ForAllTy - cmp env (AppTy _ _) (TyVarTy _) = GT - - cmp env (FunTy _ _) (TyVarTy _) = GT - cmp env (FunTy _ _) (AppTy _ _) = GT - - cmp env (TyConApp _ _) (TyVarTy _) = GT - cmp env (TyConApp _ _) (AppTy _ _) = GT - cmp env (TyConApp _ _) (FunTy _ _) = GT - - cmp env (ForAllTy _ _) other = GT - - cmp env _ _ = LT +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. - cmps env [] [] = EQ - cmps env (t:ts) [] = GT - cmps env [] (t:ts) = LT - cmps env (t1:t1s) (t2:t2s) = cmp env t1 t2 `thenCmp` cmps env t1s t2s +\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} -