X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypes%2FType.lhs;h=872feb06f55763bbc15254171cdb7ad53898243b;hb=28a464a75e14cece5db40f2765a29348273ff2d2;hp=e475674ad43333f8d368e000a2095435c7753393;hpb=4e342297f796001e7107d8c348bb023168954bc7;p=ghc-hetmet.git diff --git a/ghc/compiler/types/Type.lhs b/ghc/compiler/types/Type.lhs index e475674..872feb0 100644 --- a/ghc/compiler/types/Type.lhs +++ b/ghc/compiler/types/Type.lhs @@ -5,77 +5,76 @@ \begin{code} module Type ( - -- re-exports from TypeRep: - Type, - Kind, TyVarSubst, - - superKind, superBoxity, -- KX and BX respectively - liftedBoxity, unliftedBoxity, -- :: BX - openKindCon, -- :: KX - typeCon, -- :: BX -> KX - liftedTypeKind, unliftedTypeKind, openTypeKind, -- :: KX - mkArrowKind, mkArrowKinds, -- :: KX -> KX -> KX - + -- re-exports from TypeRep + TyThing(..), Type, PredType(..), ThetaType, funTyCon, - usageKindCon, -- :: KX - usageTypeKind, -- :: KX - usOnceTyCon, usManyTyCon, -- :: $ - usOnce, usMany, -- :: $ + -- Re-exports from Kind + module Kind, - -- exports from this module: - hasMoreBoxityInfo, defaultKind, + -- Re-exports from TyCon + PrimRep(..), mkTyVarTy, mkTyVarTys, getTyVar, getTyVar_maybe, isTyVarTy, mkAppTy, mkAppTys, splitAppTy, splitAppTys, splitAppTy_maybe, - mkFunTy, mkFunTys, splitFunTy, splitFunTy_maybe, splitFunTys, splitFunTysN, - funResultTy, funArgTy, zipFunTys, + mkFunTy, mkFunTys, splitFunTy, splitFunTy_maybe, + splitFunTys, splitFunTysN, + funResultTy, funArgTy, zipFunTys, isFunTy, mkTyConApp, mkTyConTy, tyConAppTyCon, tyConAppArgs, splitTyConApp_maybe, splitTyConApp, - splitAlgTyConApp_maybe, splitAlgTyConApp, - - mkUTy, splitUTy, splitUTy_maybe, - isUTy, uaUTy, unUTy, liftUTy, mkUTyM, - isUsageKind, isUsage, isUTyVar, - - -- Predicates and the like - mkDictTy, mkDictTys, mkPredTy, splitPredTy_maybe, predTyUnique, - splitDictTy, splitDictTy_maybe, isDictTy, predRepTy, splitDFunTy, - mkSynTy, deNoteType, - - repType, splitRepFunTys, splitNewType_maybe, typePrimRep, + repType, typePrimRep, coreView, tcView, mkForAllTy, mkForAllTys, splitForAllTy_maybe, splitForAllTys, - applyTy, applyTys, hoistForAllTys, isForAllTy, + applyTy, applyTys, isForAllTy, dropForAlls, + + -- Source types + predTypeRep, mkPredTy, mkPredTys, - TauType, RhoType, SigmaType, PredType(..), ThetaType, - ClassPred, ClassContext, mkClassPred, - getClassTys_maybe, predMentionsIPs, classesOfPreds, - isTauTy, mkRhoTy, splitRhoTy, splitMethodTy, - mkSigmaTy, isSigmaTy, splitSigmaTy, - getDFunTyKey, + -- Newtypes + splitRecNewType_maybe, -- Lifting and boxity - isUnLiftedType, isUnboxedTupleType, isAlgType, isDataType, isNewType, + isUnLiftedType, isUnboxedTupleType, isAlgType, isPrimitiveType, + isStrictType, isStrictPred, -- Free variables tyVarsOfType, tyVarsOfTypes, tyVarsOfPred, tyVarsOfTheta, - namesOfType, usageAnnOfType, 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, + tidyKind, - -- Seq - seqType, seqTypes + -- Comparison + coreEqType, tcEqType, tcEqTypes, tcCmpType, tcCmpTypes, + tcEqPred, tcCmpPred, tcEqTypeX, + -- Seq + seqType, seqTypes, + + -- Type substitutions + TvSubstEnv, emptyTvSubstEnv, -- Representation widely visible + TvSubst(..), emptyTvSubst, -- Representation visible to a few friends + mkTvSubst, mkOpenTvSubst, zipOpenTvSubst, zipTopTvSubst, mkTopTvSubst, notElemTvSubst, + getTvSubstEnv, setTvSubstEnv, getTvInScope, extendTvInScope, + extendTvSubst, extendTvSubstList, isInScope, composeTvSubst, zipTyEnv, + + -- Performing substitution on types + substTy, substTys, substTyWith, substTheta, + substPred, substTyVar, substTyVarBndr, deShadowTy, lookupTyVar, + + -- Pretty-printing + pprType, pprParendType, pprTyThingCategory, + pprPred, pprTheta, pprThetaArrow, pprClassPred ) where #include "HsVersions.h" @@ -85,55 +84,80 @@ module Type ( import TypeRep --- Other imports: - -import {-# SOURCE #-} DataCon( DataCon ) -import {-# SOURCE #-} PprType( pprType ) -- Only called in debug messages -import {-# SOURCE #-} Subst ( mkTyVarSubst, substTy ) - -- friends: -import Var ( Var, TyVar, tyVarKind, tyVarName, setTyVarName ) +import Kind +import Var ( Var, TyVar, tyVarKind, tyVarName, setTyVarName, mkTyVar ) import VarEnv import VarSet -import Name ( NamedThing(..), OccName, mkLocalName, tidyOccName ) -import NameSet -import Class ( classTyCon, Class, ClassPred, ClassContext ) -import TyCon ( TyCon, +import OccName ( tidyOccName ) +import Name ( NamedThing(..), mkInternalName, tidyNameOcc ) +import Class ( Class, classTyCon ) +import TyCon ( TyCon, isRecursiveTyCon, isPrimTyCon, isUnboxedTupleTyCon, isUnLiftedTyCon, - isFunTyCon, isDataTyCon, isNewTyCon, newTyConRep, - isAlgTyCon, isSynTyCon, tyConArity, - tyConKind, tyConDataCons, getSynTyConDefn, - tyConPrimRep + isFunTyCon, isNewTyCon, newTyConRep, newTyConRhs, + isAlgTyCon, tyConArity, + tcExpandTyCon_maybe, coreExpandTyCon_maybe, + tyConKind, PrimRep(..), tyConPrimRep, ) -- others -import Maybes ( maybeToBool ) +import StaticFlags ( opt_DictsStrict ) import SrcLoc ( noSrcLoc ) -import PrimRep ( PrimRep(..) ) -import Unique ( Unique, Uniquable(..) ) -import Util ( mapAccumL, seqList, thenCmp ) +import Util ( mapAccumL, seqList, lengthIs, snocView, thenCmp, isEqual, all2 ) import Outputable import UniqSet ( sizeUniqSet ) -- Should come via VarSet +import Maybe ( isJust ) \end{code} %************************************************************************ %* * -\subsection{Stuff to do with kinds.} + Type representation %* * %************************************************************************ +In Core, we "look through" non-recursive newtypes and PredTypes. + \begin{code} -hasMoreBoxityInfo :: Kind -> Kind -> Bool -hasMoreBoxityInfo k1 k2 - | k2 == openTypeKind = True - | otherwise = k1 == k2 - -defaultKind :: Kind -> Kind --- Used when generalising: default kind '?' to '*' -defaultKind kind | kind == openTypeKind = liftedTypeKind - | otherwise = kind +{-# INLINE coreView #-} +coreView :: Type -> Maybe Type +-- Srips off the *top layer only* of a type to give +-- its underlying representation type. +-- Returns Nothing if there is nothing to look through. +-- +-- In the case of newtypes, it returns +-- *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) +-- expandNewTcApp on R gives Just S +-- on S gives Just T +-- on T gives Nothing (no expansion) + +-- By being non-recursive and inlined, this case analysis gets efficiently +-- joined onto the case analysis that the caller is already doing +coreView (NoteTy _ ty) = Just ty +coreView (PredTy p) = Just (predTypeRep p) +coreView (TyConApp tc tys) | Just (tenv, rhs, tys') <- coreExpandTyCon_maybe tc tys + = Just (mkAppTys (substTy (mkTopTvSubst tenv) rhs) tys') + -- Its important to use mkAppTys, rather than (foldl AppTy), + -- because the function part might well return a + -- partially-applied type constructor; indeed, usually will! +coreView ty = Nothing + +----------------------------------------------- +{-# INLINE tcView #-} +tcView :: Type -> Maybe Type +-- Same, but for the type checker, which just looks through synonyms +tcView (NoteTy _ ty) = Just ty +tcView (TyConApp tc tys) | Just (tenv, rhs, tys') <- tcExpandTyCon_maybe tc tys + = Just (mkAppTys (substTy (mkTopTvSubst tenv) rhs) tys') +tcView ty = Nothing \end{code} @@ -155,25 +179,17 @@ mkTyVarTys :: [TyVar] -> [Type] mkTyVarTys = map mkTyVarTy -- a common use of mkTyVarTy getTyVar :: String -> Type -> TyVar -getTyVar msg (TyVarTy tv) = tv -getTyVar msg (PredTy p) = getTyVar msg (predRepTy p) -getTyVar msg (NoteTy _ t) = getTyVar msg t -getTyVar msg ty@(UsageTy _ _) = pprPanic "getTyVar: UTy:" (text msg $$ pprType ty) -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 (PredTy p) = getTyVar_maybe (predRepTy p) -getTyVar_maybe ty@(UsageTy _ _) = pprPanic "getTyVar_maybe: UTy:" (pprType ty) -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 (PredTy p) = isTyVarTy (predRepTy p) -isTyVarTy ty@(UsageTy _ _) = pprPanic "isTyVarTy: UTy:" (pprType ty) -isTyVarTy other = False +isTyVarTy ty = isJust (getTyVar_maybe ty) + +getTyVar_maybe :: Type -> Maybe TyVar +getTyVar_maybe ty | Just ty' <- coreView ty = getTyVar_maybe ty' +getTyVar_maybe (TyVarTy tv) = Just tv +getTyVar_maybe other = Nothing \end{code} @@ -186,15 +202,19 @@ invariant: use it. \begin{code} mkAppTy orig_ty1 orig_ty2 - = ASSERT( not (isPredTy orig_ty1) ) -- Predicates are of kind * - UASSERT2( not (isUTy orig_ty2), pprType orig_ty1 <+> pprType orig_ty2 ) - -- argument must be unannotated - mk_app orig_ty1 + = mk_app orig_ty1 where mk_app (NoteTy _ ty1) = mk_app ty1 mk_app (TyConApp tc tys) = mkTyConApp tc (tys ++ [orig_ty2]) - mk_app ty@(UsageTy _ _) = pprPanic "mkAppTy: UTy:" (pprType ty) mk_app ty1 = AppTy orig_ty1 orig_ty2 + -- Note that 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 @@ -204,29 +224,21 @@ mkAppTys orig_ty1 [] = orig_ty1 -- returns to (Ratio Integer), which has needlessly lost -- the Rational part. mkAppTys orig_ty1 orig_tys2 - = ASSERT( not (isPredTy orig_ty1) ) -- Predicates are of kind * - UASSERT2( not (any isUTy orig_tys2), pprType orig_ty1 <+> fsep (map pprType orig_tys2) ) - -- arguments must be unannotated - mk_app orig_ty1 + = mk_app orig_ty1 where mk_app (NoteTy _ ty1) = mk_app ty1 mk_app (TyConApp tc tys) = mkTyConApp tc (tys ++ orig_tys2) - mk_app ty@(UsageTy _ _) = pprPanic "mkAppTys: UTy:" (pprType ty) + -- mkTyConApp: see notes with mkAppTy mk_app ty1 = foldl AppTy orig_ty1 orig_tys2 splitAppTy_maybe :: Type -> Maybe (Type, Type) -splitAppTy_maybe (FunTy ty1 ty2) = Just (TyConApp funTyCon [unUTy ty1], unUTy ty2) +splitAppTy_maybe ty | Just ty' <- coreView ty = splitAppTy_maybe ty' +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 (PredTy p) = splitAppTy_maybe (predRepTy p) -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 ty@(UsageTy _ _) = pprPanic "splitAppTy_maybe: UTy:" (pprType ty) -splitAppTy_maybe other = Nothing +splitAppTy_maybe (TyConApp tc tys) = case snocView tys of + Nothing -> Nothing + Just (tys',ty') -> Just (TyConApp tc tys', ty') +splitAppTy_maybe other = Nothing splitAppTy :: Type -> (Type, Type) splitAppTy ty = case splitAppTy_maybe ty of @@ -236,13 +248,11 @@ splitAppTy ty = case splitAppTy_maybe ty of splitAppTys :: Type -> (Type, [Type]) splitAppTys ty = split ty ty [] where + split orig_ty ty args | Just ty' <- coreView ty = split orig_ty ty' args 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 (predRepTy p) args - split orig_ty (FunTy ty1 ty2) args = ASSERT( null args ) - (TyConApp funTyCon [], [unUTy ty1,unUTy ty2]) split orig_ty (TyConApp tc tc_args) args = (TyConApp tc [], tc_args ++ args) - split orig_ty (UsageTy _ _) args = pprPanic "splitAppTys: UTy:" (pprType orig_ty) + split orig_ty (FunTy ty1 ty2) args = ASSERT( null args ) + (TyConApp funTyCon [], [ty1,ty2]) split orig_ty ty args = (orig_ty, args) \end{code} @@ -253,142 +263,97 @@ splitAppTys ty = split ty ty [] \begin{code} mkFunTy :: Type -> Type -> Type -mkFunTy arg res = UASSERT2( isUTy arg && isUTy res, pprType arg <+> pprType res ) - FunTy arg res +mkFunTy arg res = FunTy arg res mkFunTys :: [Type] -> Type -> Type -mkFunTys tys ty = UASSERT2( all isUTy (ty:tys), fsep (map pprType (tys++[ty])) ) - foldr FunTy ty tys +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 (PredTy p) = splitFunTy (predRepTy p) -splitFunTy ty@(UsageTy _ _) = pprPanic "splitFunTy: UTy:" (pprType ty) +splitFunTy ty | Just ty' <- coreView ty = splitFunTy ty' +splitFunTy (FunTy arg res) = (arg, res) +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 (predRepTy p) -splitFunTy_maybe ty@(UsageTy _ _) = pprPanic "splitFunTy_maybe: UTy:" (pprType ty) -splitFunTy_maybe other = Nothing +splitFunTy_maybe ty | Just ty' <- coreView ty = splitFunTy_maybe ty' +splitFunTy_maybe (FunTy arg res) = Just (arg, res) +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 (PredTy p) = split args orig_ty (predRepTy p) - split args orig_ty (UsageTy _ _) = pprPanic "splitFunTys: UTy:" (pprType orig_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 (PredTy p) = split n args syn_ty (predRepTy p) - split n args syn_ty (UsageTy _ _) = pprPanic "splitFunTysN: UTy:" (pprType orig_ty) - split n args syn_ty ty = pprPanic ("splitFunTysN: " ++ msg) (int orig_n <+> pprType orig_ty) + split args orig_ty ty | Just ty' <- coreView ty = split args orig_ty ty' + split args orig_ty (FunTy arg res) = split (arg:args) res res + split args orig_ty ty = (reverse args, orig_ty) + +splitFunTysN :: Int -> Type -> ([Type], Type) +-- Split off exactly n arg tys +splitFunTysN 0 ty = ([], ty) +splitFunTysN n ty = case splitFunTy ty of { (arg, res) -> + case splitFunTysN (n-1) res of { (args, res) -> + (arg:args, res) }} 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 xs nty (PredTy p) = split acc xs nty (predRepTy p) - split acc xs nty (UsageTy _ _) = pprPanic "zipFunTys: UTy:" (ppr orig_xs <+> pprType orig_ty) - split acc (x:xs) nty ty = pprPanic "zipFunTys" (ppr orig_xs <+> pprType orig_ty) + split acc [] nty ty = (reverse acc, nty) + split acc xs nty ty + | Just ty' <- coreView ty = split acc xs nty ty' + split acc (x:xs) nty (FunTy arg res) = split ((x,arg):acc) xs res res + 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 (PredTy p) = funResultTy (predRepTy p) -funResultTy (UsageTy _ ty) = funResultTy ty -funResultTy ty = pprPanic "funResultTy" (pprType ty) +funResultTy ty | Just ty' <- coreView ty = funResultTy ty' +funResultTy (FunTy arg res) = res +funResultTy ty = pprPanic "funResultTy" (ppr ty) funArgTy :: Type -> Type -funArgTy (FunTy arg res) = arg -funArgTy (NoteTy _ ty) = funArgTy ty -funArgTy (PredTy p) = funArgTy (predRepTy p) -funArgTy (UsageTy _ ty) = funArgTy ty -funArgTy ty = pprPanic "funArgTy" (pprType ty) +funArgTy ty | Just ty' <- coreView ty = funArgTy ty' +funArgTy (FunTy arg res) = arg +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} mkTyConApp :: TyCon -> [Type] -> Type mkTyConApp tycon tys - | isFunTyCon tycon && length tys == 2 - = case tys of - (ty1:ty2:_) -> FunTy (mkUTyM ty1) (mkUTyM ty2) + | isFunTyCon tycon, [ty1,ty2] <- tys + = FunTy ty1 ty2 | otherwise - = ASSERT(not (isSynTyCon tycon)) - UASSERT2( not (any isUTy tys), ppr tycon <+> fsep (map pprType tys) ) - TyConApp tycon tys + = 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 = case splitTyConApp_maybe ty of - Just (tc,_) -> tc - Nothing -> pprPanic "tyConAppTyCon" (pprType ty) +tyConAppTyCon ty = fst (splitTyConApp ty) tyConAppArgs :: Type -> [Type] -tyConAppArgs ty = case splitTyConApp_maybe ty of - Just (_,args) -> args - Nothing -> pprPanic "tyConAppArgs" (pprType ty) +tyConAppArgs ty = snd (splitTyConApp ty) splitTyConApp :: Type -> (TyCon, [Type]) splitTyConApp ty = case splitTyConApp_maybe ty of Just stuff -> stuff - Nothing -> pprPanic "splitTyConApp" (pprType ty) + Nothing -> pprPanic "splitTyConApp" (ppr ty) splitTyConApp_maybe :: Type -> Maybe (TyCon, [Type]) +splitTyConApp_maybe ty | Just ty' <- coreView ty = splitTyConApp_maybe ty' splitTyConApp_maybe (TyConApp tc tys) = Just (tc, tys) -splitTyConApp_maybe (FunTy arg res) = Just (funTyCon, [unUTy arg,unUTy res]) -splitTyConApp_maybe (NoteTy _ ty) = splitTyConApp_maybe ty -splitTyConApp_maybe (PredTy p) = splitTyConApp_maybe (predRepTy p) -splitTyConApp_maybe (UsageTy _ ty) = splitTyConApp_maybe ty +splitTyConApp_maybe (FunTy arg res) = Just (funTyCon, [arg,res]) 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, so there had better be some. - -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 (PredTy p) = splitAlgTyConApp_maybe (predRepTy p) -splitAlgTyConApp_maybe (UsageTy _ 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 -splitAlgTyConApp (PredTy p) = splitAlgTyConApp (predRepTy p) -splitAlgTyConApp (UsageTy _ ty) = splitAlgTyConApp ty -#ifdef DEBUG -splitAlgTyConApp ty = pprPanic "splitAlgTyConApp" (pprType ty) -#endif \end{code} @@ -396,31 +361,6 @@ splitAlgTyConApp ty = pprPanic "splitAlgTyConApp" (pprType ty) SynTy ~~~~~ -\begin{code} -mkSynTy syn_tycon tys - = ASSERT( isSynTyCon syn_tycon ) - ASSERT( length tyvars == length tys ) - NoteTy (SynNote (TyConApp syn_tycon tys)) - (substTy (mkTyVarSubst tyvars tys) body) - where - (tyvars, body) = getSynTyConDefn syn_tycon - -deNoteType :: Type -> Type - -- Remove synonyms, but not Preds -deNoteType ty@(TyVarTy tyvar) = ty -deNoteType (TyConApp tycon tys) = TyConApp tycon (map deNoteType tys) -deNoteType (PredTy p) = PredTy (deNotePred p) -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) -deNoteType (UsageTy u ty) = UsageTy u (deNoteType ty) - -deNotePred :: PredType -> PredType -deNotePred (Class c tys) = Class c (map deNoteType tys) -deNotePred (IParam n ty) = IParam n (deNoteType ty) -\end{code} - Notes on type synonyms ~~~~~~~~~~~~~~~~~~~~~~ The various "split" functions (splitFunTy, splitRhoTy, splitForAllTy) try @@ -438,57 +378,53 @@ interfaces. Notably this plays a role in tcTySigs in TcBinds.lhs. Representation types ~~~~~~~~~~~~~~~~~~~~ - repType looks through (a) for-alls, and - (b) newtypes - (c) synonyms - (d) predicates - (e) usage annotations -It's useful in the back end where we're not -interested in newtypes anymore. + (b) synonyms + (c) predicates + (d) usage annotations + (e) all newtypes, including recursive ones +It's useful in the back end. \begin{code} repType :: Type -> Type -repType (ForAllTy _ ty) = repType ty -repType (NoteTy _ ty) = repType ty -repType (PredTy p) = repType (predRepTy p) -repType (UsageTy _ 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 ty | Just ty' <- coreView ty = repType ty' +repType (ForAllTy _ ty) = repType ty +repType (TyConApp tc tys) + | isNewTyCon tc = -- Recursive newtypes are opaque to coreView + -- but we must expand them here. Sure to + -- be saturated because repType is only applied + -- to types of kind * + ASSERT( isRecursiveTyCon tc && + tys `lengthIs` tyConArity tc ) + repType (new_type_rep tc tys) +repType ty = ty + +-- 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 + +-- 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 -- ?? + 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. -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 (PredTy p) = splitNewType_maybe (predRepTy p) -splitNewType_maybe (UsageTy _ 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 \end{code} - --------------------------------------------------------------------- ForAllTy ~~~~~~~~ @@ -499,338 +435,131 @@ mkForAllTy tyvar ty = mkForAllTys [tyvar] ty mkForAllTys :: [TyVar] -> Type -> Type -mkForAllTys tyvars ty - = case splitUTy_maybe ty of - Just (u,ty1) -> UASSERT2( not (mkVarSet tyvars `intersectsVarSet` tyVarsOfType u), - ptext SLIT("mkForAllTys: usage scope") - <+> ppr tyvars <+> pprType ty ) - mkUTy u (foldr ForAllTy ty1 tyvars) -- we lift usage annotations over foralls - Nothing -> foldr ForAllTy ty tyvars +mkForAllTys tyvars ty = foldr ForAllTy ty tyvars isForAllTy :: Type -> Bool isForAllTy (NoteTy _ ty) = isForAllTy ty isForAllTy (ForAllTy _ _) = True -isForAllTy (UsageTy _ ty) = isForAllTy ty 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 (predRepTy p) - splitFAT_m (ForAllTy tyvar ty) = Just(tyvar, ty) - splitFAT_m (UsageTy _ ty) = splitFAT_m ty - splitFAT_m _ = Nothing + splitFAT_m ty | Just ty' <- coreView ty = splitFAT_m ty' + 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 (PredTy p) tvs = split orig_ty (predRepTy p) tvs - split orig_ty (UsageTy _ ty) tvs = split orig_ty ty tvs - split orig_ty t tvs = (reverse tvs, orig_ty) + split orig_ty ty tvs | Just ty' <- coreView ty = split orig_ty ty' tvs + split orig_ty (ForAllTy tv ty) tvs = split ty ty (tv:tvs) + split orig_ty t tvs = (reverse tvs, orig_ty) + +dropForAlls :: Type -> Type +dropForAlls ty = snd (splitForAllTys ty) \end{code} -- (mkPiType now in CoreUtils) -Applying a for-all to its arguments. Lift usage annotation as required. +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 (PredTy p) arg = applyTy (predRepTy p) arg -applyTy (NoteTy _ fun) arg = applyTy fun arg -applyTy (ForAllTy tv ty) arg = UASSERT2( not (isUTy arg), - ptext SLIT("applyTy") - <+> pprType ty <+> pprType arg ) - substTy (mkTyVarSubst [tv] [arg]) ty -applyTy (UsageTy u ty) arg = UsageTy u (applyTy ty arg) -applyTy other arg = panic "applyTy" +applyTy ty arg | Just ty' <- coreView ty = applyTy ty' arg +applyTy (ForAllTy tv ty) arg = substTyWith [tv] [arg] ty +applyTy other arg = panic "applyTy" applyTys :: Type -> [Type] -> Type -applyTys fun_ty arg_tys - = UASSERT2( not (any isUTy arg_tys), ptext SLIT("applyTys") <+> pprType fun_ty ) - (case mu of - Just u -> UsageTy u - Nothing -> id) $ - substTy (mkTyVarSubst tvs arg_tys) ty - where - (mu, tvs, ty) = split fun_ty arg_tys - - split fun_ty [] = (Nothing, [], fun_ty) - split (NoteTy _ fun_ty) args = split fun_ty args - split (PredTy p) args = split (predRepTy p) args - split (ForAllTy tv fun_ty) (arg:args) = case split fun_ty args of - (mu, tvs, ty) -> (mu, tv:tvs, ty) - split (UsageTy u ty) args = case split ty args of - (Nothing, tvs, ty) -> (Just u, tvs, ty) - (Just _ , _ , _ ) -> pprPanic "applyTys:" - (pprType fun_ty) - split other_ty args = panic "applyTys" -\end{code} - -\begin{code} -hoistForAllTys :: Type -> Type - -- Move all the foralls to the top - -- e.g. T -> forall a. a ==> forall a. T -> a - -- Careful: LOSES USAGE ANNOTATIONS! -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) - }}} -\end{code} - - ---------------------------------------------------------------------- - UsageTy - ~~~~~~~ - -Constructing and taking apart usage types. - -\begin{code} -mkUTy :: Type -> Type -> Type -mkUTy u ty - = ASSERT2( typeKind u == usageTypeKind, ptext SLIT("mkUTy:") <+> pprType u <+> pprType ty ) - UASSERT2( not (isUTy ty), ptext SLIT("mkUTy:") <+> pprType u <+> pprType ty ) - -- if u == usMany then ty else : ToDo? KSW 2000-10 -#ifdef DO_USAGES - UsageTy u ty -#else - ty -#endif - -splitUTy :: Type -> (Type {- :: $ -}, Type) -splitUTy orig_ty - = case splitUTy_maybe orig_ty of - Just (u,ty) -> (u,ty) -#ifdef DO_USAGES - Nothing -> pprPanic "splitUTy:" (pprType orig_ty) -#else - Nothing -> (usMany,orig_ty) -- default annotation ToDo KSW 2000-10 -#endif - -splitUTy_maybe :: Type -> Maybe (Type {- :: $ -}, Type) -splitUTy_maybe (UsageTy u ty) = Just (u,ty) -splitUTy_maybe (NoteTy _ ty) = splitUTy_maybe ty -splitUTy_maybe other_ty = Nothing - -isUTy :: Type -> Bool - -- has usage annotation -isUTy = maybeToBool . splitUTy_maybe - -uaUTy :: Type -> Type - -- extract annotation -uaUTy = fst . splitUTy - -unUTy :: Type -> Type - -- extract unannotated type -unUTy = snd . splitUTy -\end{code} - -\begin{code} -liftUTy :: (Type -> Type) -> Type -> Type - -- lift outer usage annot over operation on unannotated types -liftUTy f ty - = let - (u,ty') = splitUTy ty - in - mkUTy u (f ty') -\end{code} - -\begin{code} -mkUTyM :: Type -> Type - -- put TOP (no info) annotation on unannotated type -mkUTyM ty = mkUTy usMany ty -\end{code} - -\begin{code} -isUsageKind :: Kind -> Bool -isUsageKind k - = ASSERT( typeKind k == superKind ) - k == usageTypeKind - -isUsage :: Type -> Bool -isUsage ty - = isUsageKind (typeKind ty) - -isUTyVar :: Var -> Bool -isUTyVar v - = isUsageKind (tyVarKind v) + (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} %* * %************************************************************************ -"Dictionary" types are just ordinary data types, but you can -tell from the type constructor whether it's a dictionary or not. +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} -mkClassPred clas tys = UASSERT2( not (any isUTy tys), ppr clas <+> fsep (map pprType tys) ) - Class clas tys - -mkDictTy :: Class -> [Type] -> Type -mkDictTy clas tys = UASSERT2( not (any isUTy tys), ppr clas <+> fsep (map pprType tys) ) - mkPredTy (Class clas tys) +Source types are always lifted. -mkDictTys :: ClassContext -> [Type] -mkDictTys cxt = [mkDictTy cls tys | (cls,tys) <- cxt] +The key function is predTypeRep which gives the representation of a source type: +\begin{code} mkPredTy :: PredType -> Type mkPredTy pred = PredTy pred -predTyUnique :: PredType -> Unique -predTyUnique (IParam n _) = getUnique n -predTyUnique (Class clas tys) = getUnique clas - -predRepTy :: PredType -> Type --- Convert a predicate to its "representation type"; --- the type of evidence for that predicate, which is actually passed at runtime -predRepTy (Class clas tys) = TyConApp (classTyCon clas) tys -predRepTy (IParam n ty) = ty - -isPredTy :: Type -> Bool -isPredTy (NoteTy _ ty) = isPredTy ty -isPredTy (PredTy _) = True -isPredTy (UsageTy _ ty)= isPredTy ty -isPredTy _ = False - -isDictTy :: Type -> Bool -isDictTy (NoteTy _ ty) = isDictTy ty -isDictTy (PredTy (Class _ _)) = True -isDictTy (UsageTy _ ty) = isDictTy ty -isDictTy other = False - -splitPredTy_maybe :: Type -> Maybe PredType -splitPredTy_maybe (NoteTy _ ty) = splitPredTy_maybe ty -splitPredTy_maybe (PredTy p) = Just p -splitPredTy_maybe (UsageTy _ ty)= splitPredTy_maybe ty -splitPredTy_maybe other = Nothing - -splitDictTy :: Type -> (Class, [Type]) -splitDictTy (NoteTy _ ty) = splitDictTy ty -splitDictTy (PredTy (Class clas tys)) = (clas, tys) - -splitDictTy_maybe :: Type -> Maybe (Class, [Type]) -splitDictTy_maybe (NoteTy _ ty) = Just (splitDictTy ty) -splitDictTy_maybe (PredTy (Class clas tys)) = Just (clas, tys) -splitDictTy_maybe other = Nothing - -splitDFunTy :: Type -> ([TyVar], [PredType], Class, [Type]) --- Split the type of a dictionary function -splitDFunTy ty - = case splitSigmaTy ty of { (tvs, theta, tau) -> - case splitDictTy tau of { (clas, tys) -> - (tvs, theta, clas, tys) }} - -getClassTys_maybe :: PredType -> Maybe ClassPred -getClassTys_maybe (Class clas tys) = Just (clas, tys) -getClassTys_maybe _ = Nothing - -predMentionsIPs :: PredType -> NameSet -> Bool -predMentionsIPs (IParam n _) ns = n `elemNameSet` ns -predMentionsIPs other ns = False - -classesOfPreds :: ThetaType -> ClassContext -classesOfPreds theta = [(clas,tys) | Class clas tys <- theta] +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 newtype application +predTypeRep (IParam _ ty) = ty +predTypeRep (ClassP clas tys) = mkTyConApp (classTyCon clas) tys + -- Result might be a newtype application, but the consumer will + -- look through that too if necessary \end{code} -@isTauTy@ tests for nested for-alls. -\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 (PredTy p) = isTauTy (predRepTy p) -isTauTy (NoteTy _ ty) = isTauTy ty -isTauTy (UsageTy _ ty) = isTauTy ty -isTauTy other = False -\end{code} - -\begin{code} -mkRhoTy :: [PredType] -> Type -> Type -mkRhoTy theta ty = UASSERT2( not (isUTy ty), pprType ty ) - foldr (\p r -> FunTy (mkUTyM (mkPredTy p)) (mkUTyM 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 (UsageTy _ ty) ts = split orig_ty ty ts - split orig_ty ty ts = (reverse ts, orig_ty) -\end{code} - -The type of a method for class C is always of the form: - Forall a1..an. C a1..an => sig_ty -where sig_ty is the type given by the method's signature, and thus in general -is a ForallTy. At the point that splitMethodTy is called, it is expected -that the outer Forall has already been stripped off. splitMethodTy then -returns (C a1..an, sig_ty') where sig_ty' is sig_ty with any Notes or -Usages stripped off. - -\begin{code} -splitMethodTy :: Type -> (PredType, Type) -splitMethodTy ty = split ty - where - split (FunTy arg res) = case splitPredTy_maybe arg of - Just p -> (p, res) - Nothing -> panic "splitMethodTy" - split (NoteTy _ ty) = split ty - split (UsageTy _ ty) = split ty - split _ = panic "splitMethodTy" -\end{code} - - -isSigmaType returns true of any qualified type. It doesn't *necessarily* have -any foralls. E.g. - f :: (?x::Int) => Int -> Int - -\begin{code} -mkSigmaTy tyvars theta tau = mkForAllTys tyvars (mkRhoTy theta tau) - -isSigmaTy :: Type -> Bool -isSigmaTy (ForAllTy tyvar ty) = True -isSigmaTy (FunTy a b) = isPredTy a -isSigmaTy (NoteTy _ ty) = isSigmaTy ty -isSigmaTy (UsageTy _ ty) = isSigmaTy ty -isSigmaTy _ = False - -splitSigmaTy :: Type -> ([TyVar], [PredType], Type) -splitSigmaTy ty = - (tyvars, theta, tau) - where - (tyvars,rho) = splitForAllTys ty - (theta,tau) = splitRhoTy rho -\end{code} +%************************************************************************ +%* * + NewTypes +%* * +%************************************************************************ \begin{code} -getDFunTyKey :: Type -> OccName -- Get some string from a type, to be used to - -- construct a dictionary function name -getDFunTyKey (TyVarTy tv) = getOccName tv -getDFunTyKey (TyConApp tc _) = getOccName tc -getDFunTyKey (AppTy fun _) = getDFunTyKey fun -getDFunTyKey (NoteTy _ t) = getDFunTyKey t -getDFunTyKey (FunTy arg _) = getOccName funTyCon -getDFunTyKey (ForAllTy _ t) = getDFunTyKey t -getDFunTyKey (UsageTy _ t) = getDFunTyKey t --- PredTy shouldn't happen +splitRecNewType_maybe :: Type -> Maybe Type +-- 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 ty | Just ty' <- coreView ty = splitRecNewType_maybe ty' +splitRecNewType_maybe (TyConApp tc tys) + | isNewTyCon tc + = ASSERT( tys `lengthIs` tyConArity tc ) -- splitRecNewType_maybe only be applied + -- to *types* (of kind *) + ASSERT( isRecursiveTyCon tc ) -- Guaranteed by coreView + case newTyConRhs tc of + (tvs, rep_ty) -> ASSERT( length tvs == length tys ) + Just (substTyWith tvs tys rep_ty) + +splitRecNewType_maybe other = Nothing \end{code} @@ -847,27 +576,13 @@ getDFunTyKey (UsageTy _ t) = getDFunTyKey t 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 (NoteTy _ ty) = typeKind ty typeKind (PredTy _) = liftedTypeKind -- Predicates are always -- represented by lifted types -typeKind (AppTy fun arg) = funResultTy (typeKind fun) - -typeKind (FunTy arg res) = fix_up (typeKind res) - where - fix_up (TyConApp tycon _) | tycon == typeCon - || tycon == openKindCon = liftedTypeKind - fix_up (NoteTy _ kind) = fix_up kind - fix_up kind = kind - -- The basic story is - -- typeKind (FunTy arg res) = typeKind res - -- But a function is lifted regardless of its result type - -- Hence the strange fix-up. - -- Note that 'res', being the result of a FunTy, can't have - -- a strange kind like (*->*). - +typeKind (AppTy fun arg) = kindFunResult (typeKind fun) +typeKind (FunTy arg res) = liftedTypeKind typeKind (ForAllTy tv ty) = typeKind ty -typeKind (UsageTy _ ty) = typeKind ty -- we don't have separate kinds for ann/unann \end{code} @@ -875,24 +590,22 @@ typeKind (UsageTy _ ty) = typeKind ty -- we don't have separate kinds f Free variables of a type ~~~~~~~~~~~~~~~~~~~~~~~~ \begin{code} - tyVarsOfType :: Type -> TyVarSet +-- NB: for type synonyms tyVarsOfType does *not* expand the synonym tyVarsOfType (TyVarTy tv) = unitVarSet tv tyVarsOfType (TyConApp tycon tys) = tyVarsOfTypes tys tyVarsOfType (NoteTy (FTVNote tvs) ty2) = tvs -tyVarsOfType (NoteTy (SynNote ty1) ty2) = tyVarsOfType ty1 -tyVarsOfType (PredTy p) = tyVarsOfPred p +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 -tyVarsOfType (UsageTy u ty) = tyVarsOfType u `unionVarSet` tyVarsOfType ty +tyVarsOfType (ForAllTy tyvar ty) = delVarSet (tyVarsOfType ty) tyvar 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 @@ -901,44 +614,6 @@ tyVarsOfTheta = foldr (unionVarSet . tyVarsOfPred) emptyVarSet 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 (PredTy p) = namesOfType (predRepTy p) -namesOfType (FunTy arg res) = namesOfType arg `unionNameSets` namesOfType res -namesOfType (AppTy fun arg) = namesOfType fun `unionNameSets` namesOfType arg -namesOfType (ForAllTy tyvar ty) = namesOfType ty `delFromNameSet` getName tyvar -namesOfType (UsageTy u ty) = namesOfType u `unionNameSets` namesOfType ty - -namesOfTypes tys = foldr (unionNameSets . namesOfType) emptyNameSet tys -\end{code} - -Usage annotations of a type -~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -Get a list of usage annotations of a type, *in left-to-right pre-order*. - -\begin{code} -usageAnnOfType :: Type -> [Type] -usageAnnOfType ty - = goS ty - where - goT (TyVarTy _) = [] - goT (AppTy ty1 ty2) = goT ty1 ++ goT ty2 - goT (TyConApp tc tys) = concatMap goT tys - goT (FunTy sty1 sty2) = goS sty1 ++ goS sty2 - goT (ForAllTy mv ty) = goT ty - goT (PredTy p) = goT (predRepTy p) - goT ty@(UsageTy _ _) = pprPanic "usageAnnOfType: unexpected usage:" (pprType ty) - goT (NoteTy note ty) = goT ty - - goS sty = case splitUTy sty of - (u,tty) -> u : goT tty \end{code} @@ -954,28 +629,31 @@ 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' = tidyNameOcc name occ' 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 @@ -986,22 +664,21 @@ 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 (PredTy p) = PredTy (go_pred p) - 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 (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 - go (UsageTy u ty) = (UsageTy SAPPLY (go u)) SAPPLY (go ty) + (envp, tvp) = tidyTyVarBndr env tv - go_note (SynNote ty) = SynNote SAPPLY (go ty) go_note note@(FTVNote ftvs) = note -- No need to tidy the free tyvars - go_pred (Class c tys) = Class c (tidyTypes env tys) - go_pred (IParam n ty) = IParam n (go ty) - 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} @@ -1013,8 +690,7 @@ 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 @@ -1024,6 +700,43 @@ tidyTopType ty = tidyType emptyTidyEnv ty \end{code} +%************************************************************************ +%* * + Tidying Kinds +%* * +%************************************************************************ + +We use a grevious hack for tidying KindVars. A TidyEnv contains +a (VarEnv Var) substitution, to express the renaming; but +KindVars are not Vars. The Right Thing ultimately is to make them +into Vars (and perhaps make Kinds into Types), but I just do a hack +here: I make up a TyVar just to remember the new OccName for the +renamed KindVar + +\begin{code} +tidyKind :: TidyEnv -> Kind -> (TidyEnv, Kind) +tidyKind env@(tidy_env, subst) (KindVar kvar) + | Just tv <- lookupVarEnv_Directly subst uniq + = (env, KindVar (setKindVarOcc kvar (getOccName tv))) + | otherwise + = ((tidy', subst'), KindVar kvar') + where + uniq = kindVarUniq kvar + (tidy', occ') = tidyOccName tidy_env (kindVarOcc kvar) + kvar' = setKindVarOcc kvar occ' + fake_tv = mkTyVar tv_name (panic "tidyKind:fake tv kind") + tv_name = mkInternalName uniq occ' noSrcLoc + subst' = extendVarEnv subst fake_tv fake_tv + +tidyKind env (FunKind k1 k2) + = (env2, FunKind k1' k2') + where + (env1, k1') = tidyKind env k1 + (env2, k2') = tidyKind env1 k2 + +tidyKind env k = (env, k) -- Atomic kinds +\end{code} + %************************************************************************ %* * @@ -1039,11 +752,10 @@ 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 (UsageTy _ ty) = isUnLiftedType ty -isUnLiftedType other = False +isUnLiftedType ty | Just ty' <- coreView ty = isUnLiftedType ty' +isUnLiftedType (ForAllTy tv ty) = isUnLiftedType ty +isUnLiftedType (TyConApp tc _) = isUnLiftedTyCon tc +isUnLiftedType other = False isUnboxedTupleType :: Type -> Bool isUnboxedTupleType ty = case splitTyConApp_maybe ty of @@ -1053,21 +765,41 @@ 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. -isNewType :: Type -> Bool -isNewType ty = case splitTyConApp_maybe ty of - Just (tc, ty_args) -> ASSERT( length ty_args == tyConArity tc ) - isNewTyCon tc +\begin{code} +isStrictType (PredTy pred) = isStrictPred pred +isStrictType ty | Just ty' <- coreView ty = isStrictType ty' +isStrictType (ForAllTy tv ty) = isStrictType ty +isStrictType (TyConApp tc _) = isUnLiftedTyCon tc +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} @@ -1087,100 +819,414 @@ seqType (NoteTy note t2) = seqNote note `seq` seqType t2 seqType (PredTy p) = seqPred p seqType (TyConApp tc tys) = tc `seq` seqTypes tys seqType (ForAllTy tv ty) = tv `seq` seqType ty -seqType (UsageTy u ty) = seqType u `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 (Class c tys) = c `seq` seqTypes tys -seqPred (IParam n ty) = n `seq` seqType ty +seqPred (ClassP c tys) = c `seq` seqTypes tys +seqPred (IParam n ty) = n `seq` seqType ty \end{code} %************************************************************************ %* * -\subsection{Equality on types} + Equality for Core types + (We don't use instances so that we know where it happens) %* * %************************************************************************ +Note that eqType works right even for partial applications of newtypes. +See Note [Newtype eta] in TyCon.lhs \begin{code} -instance Eq Type where - ty1 == ty2 = case ty1 `compare` ty2 of { EQ -> True; other -> False } - -instance Ord Type where - compare ty1 ty2 = cmpTy emptyVarEnv ty1 ty2 - -cmpTy :: TyVarEnv TyVar -> Type -> Type -> Ordering - -- 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 - - -- Get rid of NoteTy -cmpTy env (NoteTy _ ty1) ty2 = cmpTy env ty1 ty2 -cmpTy env ty1 (NoteTy _ ty2) = cmpTy env ty1 ty2 - - -- Get rid of PredTy -cmpTy env (PredTy p1) (PredTy p2) = cmpPred env p1 p2 -cmpTy env (PredTy p1) ty2 = cmpTy env (predRepTy p1) ty2 -cmpTy env ty1 (PredTy p2) = cmpTy env ty1 (predRepTy p2) - - -- Deal with equal constructors -cmpTy env (TyVarTy tv1) (TyVarTy tv2) = case lookupVarEnv env tv1 of - Just tv1a -> tv1a `compare` tv2 - Nothing -> tv1 `compare` tv2 - -cmpTy env (AppTy f1 a1) (AppTy f2 a2) = cmpTy env f1 f2 `thenCmp` cmpTy env a1 a2 -cmpTy env (FunTy f1 a1) (FunTy f2 a2) = cmpTy env f1 f2 `thenCmp` cmpTy env a1 a2 -cmpTy env (TyConApp tc1 tys1) (TyConApp tc2 tys2) = (tc1 `compare` tc2) `thenCmp` (cmpTys env tys1 tys2) -cmpTy env (ForAllTy tv1 t1) (ForAllTy tv2 t2) = cmpTy (extendVarEnv env tv1 tv2) t1 t2 -cmpTy env (UsageTy u1 t1) (UsageTy u2 t2) = cmpTy env u1 u2 `thenCmp` cmpTy env t1 t2 - - -- Deal with the rest: TyVarTy < AppTy < FunTy < TyConApp < ForAllTy < UsageTy -cmpTy env (AppTy _ _) (TyVarTy _) = GT - -cmpTy env (FunTy _ _) (TyVarTy _) = GT -cmpTy env (FunTy _ _) (AppTy _ _) = GT - -cmpTy env (TyConApp _ _) (TyVarTy _) = GT -cmpTy env (TyConApp _ _) (AppTy _ _) = GT -cmpTy env (TyConApp _ _) (FunTy _ _) = GT - -cmpTy env (ForAllTy _ _) (TyVarTy _) = GT -cmpTy env (ForAllTy _ _) (AppTy _ _) = GT -cmpTy env (ForAllTy _ _) (FunTy _ _) = GT -cmpTy env (ForAllTy _ _) (TyConApp _ _) = GT +coreEqType :: Type -> Type -> Bool +coreEqType t1 t2 + = eq rn_env t1 t2 + where + rn_env = mkRnEnv2 (mkInScopeSet (tyVarsOfType t1 `unionVarSet` tyVarsOfType t2)) + + eq env (TyVarTy tv1) (TyVarTy tv2) = rnOccL env tv1 == rnOccR env tv2 + eq env (ForAllTy tv1 t1) (ForAllTy tv2 t2) = eq (rnBndr2 env tv1 tv2) t1 t2 + eq env (AppTy s1 t1) (AppTy s2 t2) = eq env s1 s2 && eq env t1 t2 + eq env (FunTy s1 t1) (FunTy s2 t2) = eq env s1 s2 && eq env t1 t2 + eq env (TyConApp tc1 tys1) (TyConApp tc2 tys2) + | tc1 == tc2, all2 (eq env) tys1 tys2 = True + -- The lengths should be equal because + -- the two types have the same kind + -- NB: if the type constructors differ that does not + -- necessarily mean that the types aren't equal + -- (synonyms, newtypes) + -- Even if the type constructors are the same, but the arguments + -- differ, the two types could be the same (e.g. if the arg is just + -- ignored in the RHS). In both these cases we fall through to an + -- attempt to expand one side or the other. + + -- Now deal with newtypes, synonyms, pred-tys + eq env t1 t2 | Just t1' <- coreView t1 = eq env t1' t2 + | Just t2' <- coreView t2 = eq env t1 t2' + + -- Fall through case; not equal! + eq env t1 t2 = False +\end{code} -cmpTy env (UsageTy _ _) other = GT - -cmpTy env _ _ = LT +%************************************************************************ +%* * + Comparision for source types + (We don't use instances so that we know where it happens) +%* * +%************************************************************************ + +Note that + tcEqType, tcCmpType +do *not* look through newtypes, PredTypes + +\begin{code} +tcEqType :: Type -> Type -> Bool +tcEqType t1 t2 = isEqual $ cmpType t1 t2 -cmpTys env [] [] = EQ -cmpTys env (t:ts) [] = GT -cmpTys env [] (t:ts) = LT -cmpTys env (t1:t1s) (t2:t2s) = cmpTy env t1 t2 `thenCmp` cmpTys env t1s t2s +tcEqTypes :: [Type] -> [Type] -> Bool +tcEqTypes tys1 tys2 = isEqual $ cmpTypes tys1 tys2 + +tcCmpType :: Type -> Type -> Ordering +tcCmpType t1 t2 = cmpType t1 t2 + +tcCmpTypes :: [Type] -> [Type] -> Ordering +tcCmpTypes tys1 tys2 = cmpTypes tys1 tys2 + +tcEqPred :: PredType -> PredType -> Bool +tcEqPred p1 p2 = isEqual $ cmpPred p1 p2 + +tcCmpPred :: PredType -> PredType -> Ordering +tcCmpPred p1 p2 = cmpPred p1 p2 + +tcEqTypeX :: RnEnv2 -> Type -> Type -> Bool +tcEqTypeX env t1 t2 = isEqual $ cmpTypeX env t1 t2 \end{code} +Now here comes the real worker + \begin{code} -instance Eq PredType where - p1 == p2 = case p1 `compare` p2 of { EQ -> True; other -> False } +cmpType :: Type -> Type -> Ordering +cmpType t1 t2 = cmpTypeX rn_env t1 t2 + where + rn_env = mkRnEnv2 (mkInScopeSet (tyVarsOfType t1 `unionVarSet` tyVarsOfType t2)) + +cmpTypes :: [Type] -> [Type] -> Ordering +cmpTypes ts1 ts2 = cmpTypesX rn_env ts1 ts2 + where + rn_env = mkRnEnv2 (mkInScopeSet (tyVarsOfTypes ts1 `unionVarSet` tyVarsOfTypes ts2)) + +cmpPred :: PredType -> PredType -> Ordering +cmpPred p1 p2 = cmpPredX rn_env p1 p2 + where + rn_env = mkRnEnv2 (mkInScopeSet (tyVarsOfPred p1 `unionVarSet` tyVarsOfPred p2)) + +cmpTypeX :: RnEnv2 -> Type -> Type -> Ordering -- Main workhorse +cmpTypeX env t1 t2 | Just t1' <- tcView t1 = cmpTypeX env t1' t2 + | Just t2' <- tcView t2 = cmpTypeX env t1 t2' + +cmpTypeX env (TyVarTy tv1) (TyVarTy tv2) = rnOccL env tv1 `compare` rnOccR env tv2 +cmpTypeX env (ForAllTy tv1 t1) (ForAllTy tv2 t2) = cmpTypeX (rnBndr2 env tv1 tv2) t1 t2 +cmpTypeX env (AppTy s1 t1) (AppTy s2 t2) = cmpTypeX env s1 s2 `thenCmp` cmpTypeX env t1 t2 +cmpTypeX env (FunTy s1 t1) (FunTy s2 t2) = cmpTypeX env s1 s2 `thenCmp` cmpTypeX env t1 t2 +cmpTypeX env (PredTy p1) (PredTy p2) = cmpPredX env p1 p2 +cmpTypeX env (TyConApp tc1 tys1) (TyConApp tc2 tys2) = (tc1 `compare` tc2) `thenCmp` cmpTypesX env tys1 tys2 +cmpTypeX env t1 (NoteTy _ t2) = cmpTypeX env t1 t2 + + -- Deal with the rest: TyVarTy < AppTy < FunTy < TyConApp < ForAllTy < PredTy +cmpTypeX env (AppTy _ _) (TyVarTy _) = GT + +cmpTypeX env (FunTy _ _) (TyVarTy _) = GT +cmpTypeX env (FunTy _ _) (AppTy _ _) = GT + +cmpTypeX env (TyConApp _ _) (TyVarTy _) = GT +cmpTypeX env (TyConApp _ _) (AppTy _ _) = GT +cmpTypeX env (TyConApp _ _) (FunTy _ _) = GT + +cmpTypeX env (ForAllTy _ _) (TyVarTy _) = GT +cmpTypeX env (ForAllTy _ _) (AppTy _ _) = GT +cmpTypeX env (ForAllTy _ _) (FunTy _ _) = GT +cmpTypeX env (ForAllTy _ _) (TyConApp _ _) = GT + +cmpTypeX env (PredTy _) t2 = GT -instance Ord PredType where - compare p1 p2 = cmpPred emptyVarEnv p1 p2 +cmpTypeX env _ _ = LT -cmpPred :: TyVarEnv TyVar -> PredType -> PredType -> Ordering -cmpPred env (IParam n1 ty1) (IParam n2 ty2) = (n1 `compare` n2) `thenCmp` (cmpTy env ty1 ty2) +------------- +cmpTypesX :: RnEnv2 -> [Type] -> [Type] -> Ordering +cmpTypesX env [] [] = EQ +cmpTypesX env (t1:tys1) (t2:tys2) = cmpTypeX env t1 t2 `thenCmp` cmpTypesX env tys1 tys2 +cmpTypesX env [] tys = LT +cmpTypesX env ty [] = GT + +------------- +cmpPredX :: RnEnv2 -> PredType -> PredType -> Ordering +cmpPredX env (IParam n1 ty1) (IParam n2 ty2) = (n1 `compare` n2) `thenCmp` cmpTypeX env ty1 ty2 -- Compare types as well as names for implicit parameters -- This comparison is used exclusively (I think) for the -- finite map built in TcSimplify -cmpPred env (Class c1 tys1) (Class c2 tys2) = (c1 `compare` c2) `thenCmp` (cmpTys env tys1 tys2) -cmpPred env (IParam _ _) (Class _ _) = LT -cmpPred env (Class _ _) (IParam _ _) = GT +cmpPredX env (ClassP c1 tys1) (ClassP c2 tys2) = (c1 `compare` c2) `thenCmp` cmpTypesX env tys1 tys2 +cmpPredX env (IParam _ _) (ClassP _ _) = LT +cmpPredX env (ClassP _ _) (IParam _ _) = GT +\end{code} + +PredTypes are used as a FM key in TcSimplify, +so we take the easy path and make them an instance of Ord + +\begin{code} +instance Eq PredType where { (==) = tcEqPred } +instance Ord PredType where { compare = tcCmpPred } +\end{code} + + +%************************************************************************ +%* * + Type substitutions +%* * +%************************************************************************ + +\begin{code} +data TvSubst + = TvSubst InScopeSet -- The in-scope type variables + TvSubstEnv -- The substitution itself + -- See Note [Apply Once] + +{- ---------------------------------------------------------- + Note [Apply Once] + +We use TvSubsts to instantiate things, and we might instantiate + forall a b. ty +\with the types + [a, b], or [b, a]. +So the substition might go [a->b, b->a]. A similar situation arises in Core +when we find a beta redex like + (/\ a /\ b -> e) b a +Then we also end up with a substition that permutes type variables. Other +variations happen to; for example [a -> (a, b)]. + + *************************************************** + *** So a TvSubst must be applied precisely once *** + *************************************************** + +A TvSubst is not idempotent, but, unlike the non-idempotent substitution +we use during unifications, it must not be repeatedly applied. +-------------------------------------------------------------- -} + + +type TvSubstEnv = TyVarEnv Type + -- A TvSubstEnv is used both inside a TvSubst (with the apply-once + -- invariant discussed in Note [Apply Once]), and also independently + -- in the middle of matching, and unification (see Types.Unify) + -- So you have to look at the context to know if it's idempotent or + -- apply-once or whatever +emptyTvSubstEnv :: TvSubstEnv +emptyTvSubstEnv = emptyVarEnv + +composeTvSubst :: InScopeSet -> TvSubstEnv -> TvSubstEnv -> TvSubstEnv +-- (compose env1 env2)(x) is env1(env2(x)); i.e. apply env2 then env1 +-- It assumes that both are idempotent +-- Typically, env1 is the refinement to a base substitution env2 +composeTvSubst in_scope env1 env2 + = env1 `plusVarEnv` mapVarEnv (substTy subst1) env2 + -- First apply env1 to the range of env2 + -- Then combine the two, making sure that env1 loses if + -- both bind the same variable; that's why env1 is the + -- *left* argument to plusVarEnv, because the right arg wins + where + subst1 = TvSubst in_scope env1 + +emptyTvSubst = TvSubst emptyInScopeSet emptyVarEnv + +isEmptyTvSubst :: TvSubst -> Bool +isEmptyTvSubst (TvSubst _ env) = isEmptyVarEnv env + +mkTvSubst :: InScopeSet -> TvSubstEnv -> TvSubst +mkTvSubst = TvSubst + +getTvSubstEnv :: TvSubst -> TvSubstEnv +getTvSubstEnv (TvSubst _ env) = env + +getTvInScope :: TvSubst -> InScopeSet +getTvInScope (TvSubst in_scope _) = in_scope + +isInScope :: Var -> TvSubst -> Bool +isInScope v (TvSubst in_scope _) = v `elemInScopeSet` in_scope + +notElemTvSubst :: TyVar -> TvSubst -> Bool +notElemTvSubst tv (TvSubst _ env) = not (tv `elemVarEnv` env) + +setTvSubstEnv :: TvSubst -> TvSubstEnv -> TvSubst +setTvSubstEnv (TvSubst in_scope _) env = TvSubst in_scope env + +extendTvInScope :: TvSubst -> [Var] -> TvSubst +extendTvInScope (TvSubst in_scope env) vars = TvSubst (extendInScopeSetList in_scope vars) env + +extendTvSubst :: TvSubst -> TyVar -> Type -> TvSubst +extendTvSubst (TvSubst in_scope env) tv ty = TvSubst in_scope (extendVarEnv env tv ty) + +extendTvSubstList :: TvSubst -> [TyVar] -> [Type] -> TvSubst +extendTvSubstList (TvSubst in_scope env) tvs tys + = TvSubst in_scope (extendVarEnvList env (tvs `zip` tys)) + +-- mkOpenTvSubst and zipOpenTvSubst generate the in-scope set from +-- the types given; but it's just a thunk so with a bit of luck +-- it'll never be evaluated + +mkOpenTvSubst :: TvSubstEnv -> TvSubst +mkOpenTvSubst env = TvSubst (mkInScopeSet (tyVarsOfTypes (varEnvElts env))) env + +zipOpenTvSubst :: [TyVar] -> [Type] -> TvSubst +zipOpenTvSubst tyvars tys +#ifdef DEBUG + | length tyvars /= length tys + = pprTrace "zipOpenTvSubst" (ppr tyvars $$ ppr tys) emptyTvSubst + | otherwise +#endif + = TvSubst (mkInScopeSet (tyVarsOfTypes tys)) (zipTyEnv tyvars tys) + +-- mkTopTvSubst is called when doing top-level substitutions. +-- Here we expect that the free vars of the range of the +-- substitution will be empty. +mkTopTvSubst :: [(TyVar, Type)] -> TvSubst +mkTopTvSubst prs = TvSubst emptyInScopeSet (mkVarEnv prs) + +zipTopTvSubst :: [TyVar] -> [Type] -> TvSubst +zipTopTvSubst tyvars tys +#ifdef DEBUG + | length tyvars /= length tys + = pprTrace "zipOpenTvSubst" (ppr tyvars $$ ppr tys) emptyTvSubst + | otherwise +#endif + = TvSubst emptyInScopeSet (zipTyEnv tyvars tys) + +zipTyEnv :: [TyVar] -> [Type] -> TvSubstEnv +zipTyEnv tyvars tys +#ifdef DEBUG + | length tyvars /= length tys + = pprTrace "mkTopTvSubst" (ppr tyvars $$ ppr tys) emptyVarEnv + | otherwise +#endif + = zip_ty_env tyvars tys emptyVarEnv + +-- Later substitutions in the list over-ride earlier ones, +-- but there should be no loops +zip_ty_env [] [] env = env +zip_ty_env (tv:tvs) (ty:tys) env = zip_ty_env tvs tys (extendVarEnv env tv ty) + -- There used to be a special case for when + -- ty == TyVarTy tv + -- (a not-uncommon case) in which case the substitution was dropped. + -- But the type-tidier changes the print-name of a type variable without + -- changing the unique, and that led to a bug. Why? Pre-tidying, we had + -- a type {Foo t}, where Foo is a one-method class. So Foo is really a newtype. + -- And it happened that t was the type variable of the class. Post-tiding, + -- it got turned into {Foo t2}. The ext-core printer expanded this using + -- sourceTypeRep, but that said "Oh, t == t2" because they have the same unique, + -- and so generated a rep type mentioning t not t2. + -- + -- Simplest fix is to nuke the "optimisation" +zip_ty_env tvs tys env = pprTrace "Var/Type length mismatch: " (ppr tvs $$ ppr tys) env +-- zip_ty_env _ _ env = env + +instance Outputable TvSubst where + ppr (TvSubst ins env) + = sep[ ptext SLIT(" ppr ins), + nest 2 (ptext SLIT("Env:") <+> ppr env) ] +\end{code} + +%************************************************************************ +%* * + Performing type substitutions +%* * +%************************************************************************ + +\begin{code} +substTyWith :: [TyVar] -> [Type] -> Type -> Type +substTyWith tvs tys = ASSERT( length tvs == length tys ) + substTy (zipOpenTvSubst tvs tys) + +substTy :: TvSubst -> Type -> Type +substTy subst ty | isEmptyTvSubst subst = ty + | otherwise = subst_ty subst ty + +substTys :: TvSubst -> [Type] -> [Type] +substTys subst tys | isEmptyTvSubst subst = tys + | otherwise = map (subst_ty subst) tys + +substTheta :: TvSubst -> ThetaType -> ThetaType +substTheta subst theta + | isEmptyTvSubst subst = theta + | otherwise = map (substPred subst) theta + +substPred :: TvSubst -> PredType -> PredType +substPred subst (IParam n ty) = IParam n (subst_ty subst ty) +substPred subst (ClassP clas tys) = ClassP clas (map (subst_ty subst) tys) + +deShadowTy :: TyVarSet -> Type -> Type -- Remove any nested binders mentioning tvs +deShadowTy tvs ty + = subst_ty (mkTvSubst in_scope emptyTvSubstEnv) ty + where + in_scope = mkInScopeSet tvs + +-- Note that the in_scope set is poked only if we hit a forall +-- so it may often never be fully computed +subst_ty subst ty + = go ty + where + go (TyVarTy tv) = substTyVar subst tv + go (TyConApp tc tys) = let args = map go tys + in args `seqList` TyConApp tc args + + go (PredTy p) = PredTy $! (substPred subst p) + + 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) + -- The mkAppTy smart constructor is important + -- we might be replacing (a Int), represented with App + -- by [Int], represented with TyConApp + go (ForAllTy tv ty) = case substTyVarBndr subst tv of + (subst', tv') -> ForAllTy tv' $! (subst_ty subst' ty) + +substTyVar :: TvSubst -> TyVar -> Type +substTyVar subst tv + = case lookupTyVar subst tv of + Nothing -> TyVarTy tv + Just ty' -> ty' -- See Note [Apply Once] + +lookupTyVar :: TvSubst -> TyVar -> Maybe Type +lookupTyVar (TvSubst in_scope env) tv = lookupVarEnv env tv + +substTyVarBndr :: TvSubst -> TyVar -> (TvSubst, TyVar) +substTyVarBndr subst@(TvSubst in_scope env) old_var + | old_var == new_var -- No need to clone + -- But we *must* zap any current substitution for the variable. + -- For example: + -- (\x.e) with id_subst = [x |-> e'] + -- Here we must simply zap the substitution for x + -- + -- The new_id isn't cloned, but it may have a different type + -- etc, so we must return it, not the old id + = (TvSubst (in_scope `extendInScopeSet` new_var) + (delVarEnv env old_var), + new_var) + + | otherwise -- The new binder 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 + = (TvSubst (in_scope `extendInScopeSet` new_var) + (extendVarEnv env old_var (TyVarTy new_var)), + new_var) + where + new_var = uniqAway in_scope old_var + -- The uniqAway part makes sure the new variable is not already in scope \end{code}