X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2Fghci%2FRtClosureInspect.hs;h=19403aeea2900e3d76606063ebbb6c7aadf858b0;hb=f2643821042fd3d859e7c6eaad459e6a2cb756a2;hp=3ca0b0bd83fcbef22afe73796dcb87d901d0226b;hpb=87c1c2ff25f844f30c37d77cb9f4feeae9c55d7b;p=ghc-hetmet.git diff --git a/compiler/ghci/RtClosureInspect.hs b/compiler/ghci/RtClosureInspect.hs index 3ca0b0b..19403ae 100644 --- a/compiler/ghci/RtClosureInspect.hs +++ b/compiler/ghci/RtClosureInspect.hs @@ -25,7 +25,7 @@ module RtClosureInspect( mapTermType, termTyVars, -- unsafeDeepSeq, - reconstructType + cvReconstructType ) where #include "HsVersions.h" @@ -37,7 +37,8 @@ import HscTypes ( HscEnv ) import DataCon import Type -import TcRnMonad ( TcM, initTcPrintErrors, ioToTcRn, recoverM, writeMutVar ) +import TcRnMonad ( TcM, initTcPrintErrors, ioToTcRn, recoverM + , writeMutVar ) import TcType import TcMType import TcUnify @@ -47,6 +48,7 @@ import Var import Name import VarEnv import OccName +import Util import VarSet import {-#SOURCE#-} TcRnDriver ( tcRnRecoverDataCon ) @@ -69,6 +71,7 @@ import Data.Maybe import Data.Array.Base import Data.List ( partition, nub ) import Foreign +import System.IO.Unsafe --------------------------------------------- -- * A representation of semi evaluated Terms @@ -86,7 +89,8 @@ import Foreign -} data Term = Term { ty :: Type - , dc :: DataCon + , dc :: DataCon -- The heap datacon. If ty is a newtype, + -- this is NOT the newtype datacon , val :: HValue , subTerms :: [Term] } @@ -158,7 +162,8 @@ getClosureData a = ptrsList = Array 0 (fromIntegral$ elems) ptrs nptrs_data = [W# (indexWordArray# nptrs i) | I# i <- [0.. fromIntegral (BCI.nptrs itbl)] ] - ptrsList `seq` return (Closure tipe (Ptr iptr) itbl ptrsList nptrs_data) + ptrsList `seq` + return (Closure tipe (Ptr iptr) itbl ptrsList nptrs_data) readCType :: Integral a => a -> ClosureType readCType i @@ -204,7 +209,7 @@ amap' f (Array i0 i arr#) = map (\(I# i#) -> case indexArray# arr# i# of unsafeDeepSeq :: a -> b -> b unsafeDeepSeq = unsafeDeepSeq1 2 where unsafeDeepSeq1 0 a b = seq a $! b - unsafeDeepSeq1 i a b -- 1st case avoids infinite loops for non reducible thunks + unsafeDeepSeq1 i a b -- 1st case avoids infinite loops for non reducible thunks | not (isConstr tipe) = seq a $! unsafeDeepSeq1 (i-1) a b -- | unsafePerformIO (isFullyEvaluated a) = b | otherwise = case unsafePerformIO (getClosureData a) of @@ -212,7 +217,8 @@ unsafeDeepSeq = unsafeDeepSeq1 2 where tipe = unsafePerformIO (getClosureType a) -} isPointed :: Type -> Bool -isPointed t | Just (t, _) <- splitTyConApp_maybe t = not$ isUnliftedTypeKind (tyConKind t) +isPointed t | Just (t, _) <- splitTyConApp_maybe t + = not$ isUnliftedTypeKind (tyConKind t) isPointed _ = True extractUnboxed :: [Type] -> Closure -> [[Word]] @@ -234,7 +240,8 @@ sizeofTyCon = sizeofPrimRep . tyConPrimRep data TermFold a = TermFold { fTerm :: Type -> DataCon -> HValue -> [a] -> a , fPrim :: Type -> [Word] -> a - , fSuspension :: ClosureType -> Maybe Type -> HValue -> Maybe Name -> a + , fSuspension :: ClosureType -> Maybe Type -> HValue + -> Maybe Name -> a } foldTerm :: TermFold a -> Term -> a @@ -271,73 +278,83 @@ termTyVars = foldTerm TermFold { -- Pretty printing of terms ---------------------------------- -app_prec::Int +app_prec,cons_prec ::Int app_prec = 10 +cons_prec = 5 -- TODO Extract this info from GHC itself -pprTerm :: Int -> Term -> SDoc -pprTerm p Term{dc=dc, subTerms=tt} -{- | dataConIsInfix dc, (t1:t2:tt') <- tt +pprTerm y p t | Just doc <- pprTermM y p t = doc + +pprTermM :: Monad m => (Int -> Term -> m SDoc) -> Int -> Term -> m SDoc +pprTermM y p t@Term{dc=dc, subTerms=tt, ty=ty} +{- | dataConIsInfix dc, (t1:t2:tt') <- tt --TODO fixity = parens (pprTerm1 True t1 <+> ppr dc <+> pprTerm1 True ppr t2) <+> hsep (map (pprTerm1 True) tt) -} - | null tt = ppr dc - | otherwise = cparen (p >= app_prec) - (ppr dc <+> sep (map (pprTerm app_prec) tt)) - - where fixity = undefined - -pprTerm _ t = pprTerm1 t - -pprTerm1 Prim{value=words, ty=ty} = text$ repPrim (tyConAppTyCon ty) words -pprTerm1 t@Term{} = pprTerm 0 t -pprTerm1 Suspension{bound_to=Nothing} = char '_' -- <> ppr ct <> char '_' -pprTerm1 Suspension{mb_ty=Just ty, bound_to=Just n} - | Just _ <- splitFunTy_maybe ty = ptext SLIT("") - | otherwise = parens$ ppr n <> text "::" <> ppr ty - - -cPprTerm :: forall m. Monad m => ((Int->Term->m SDoc)->[Int->Term->m (Maybe SDoc)]) -> Term -> m SDoc + | null tt = return$ ppr dc + | Just (tc,_) <- splitNewTyConApp_maybe ty + , isNewTyCon tc + , Just new_dc <- maybeTyConSingleCon tc = do + real_value <- y 10 t{ty=repType ty} + return$ cparen (p >= app_prec) (ppr new_dc <+> real_value) + | otherwise = do + tt_docs <- mapM (y app_prec) tt + return$ cparen (p >= app_prec) (ppr dc <+> sep tt_docs) + +pprTermM y _ t = pprTermM1 y t + +pprTermM1 _ Prim{value=words, ty=ty} = return$ text$ repPrim (tyConAppTyCon ty) + words +pprTermM1 y t@Term{} = panic "pprTermM1 - unreachable" +pprTermM1 _ Suspension{bound_to=Nothing} = return$ char '_' +pprTermM1 _ Suspension{mb_ty=Just ty, bound_to=Just n} + | Just _ <- splitFunTy_maybe ty = return$ ptext SLIT("") + | otherwise = return$ parens$ ppr n <> text "::" <> ppr ty + +-- Takes a list of custom printers with a explicit recursion knot and a term, +-- and returns the output of the first succesful printer, or the default printer +cPprTerm :: forall m. Monad m => + ((Int->Term->m SDoc)->[Int->Term->m (Maybe SDoc)]) -> Term -> m SDoc cPprTerm custom = go 0 where go prec t@Term{subTerms=tt, dc=dc} = do - let mb_customDocs = map (($t) . ($prec)) (custom go) :: [m (Maybe SDoc)] - first_success <- firstJustM mb_customDocs - case first_success of - Just doc -> return$ cparen (prec>app_prec+1) doc --- | dataConIsInfix dc, (t1:t2:tt') <- tt = - Nothing -> do pprSubterms <- mapM (go (app_prec+1)) tt - return$ cparen (prec >= app_prec) - (ppr dc <+> sep pprSubterms) - go _ t = return$ pprTerm1 t + let default_ prec t = Just `liftM` pprTermM go prec t + mb_customDocs = [pp prec t | pp <- custom go ++ [default_]] + Just doc <- firstJustM mb_customDocs + return$ cparen (prec>app_prec+1) doc + go _ t = pprTermM1 go t firstJustM (mb:mbs) = mb >>= maybe (firstJustM mbs) (return . Just) firstJustM [] = return Nothing +-- Default set of custom printers. Note that the recursion knot is explicit cPprTermBase :: Monad m => (Int->Term-> m SDoc)->[Int->Term->m (Maybe SDoc)] -cPprTermBase pprP = +cPprTermBase y = [ - ifTerm isTupleDC (\_ -> liftM (parens . hcat . punctuate comma) - . mapM (pprP (-1)) . subTerms) - , ifTerm (isDC consDataCon) (\ p Term{subTerms=[h,t]} -> doList p h t) - , ifTerm (isDC intDataCon) (coerceShow$ \(a::Int)->a) - , ifTerm (isDC charDataCon) (coerceShow$ \(a::Char)->a) --- , ifTerm (isDC wordDataCon) (coerceShow$ \(a::Word)->a) - , ifTerm (isDC floatDataCon) (coerceShow$ \(a::Float)->a) - , ifTerm (isDC doubleDataCon) (coerceShow$ \(a::Double)->a) - , ifTerm isIntegerDC (coerceShow$ \(a::Integer)->a) + ifTerm isTupleTy (\_ -> liftM (parens . hcat . punctuate comma) + . mapM (y (-1)) . subTerms) + , ifTerm (\t -> isTyCon listTyCon t && subTerms t `lengthIs` 2) + (\ p Term{subTerms=[h,t]} -> doList p h t) + , ifTerm (isTyCon intTyCon) (coerceShow$ \(a::Int)->a) + , ifTerm (isTyCon charTyCon) (coerceShow$ \(a::Char)->a) +-- , ifTerm (isTyCon wordTyCon) (coerceShow$ \(a::Word)->a) + , ifTerm (isTyCon floatTyCon) (coerceShow$ \(a::Float)->a) + , ifTerm (isTyCon doubleTyCon) (coerceShow$ \(a::Double)->a) + , ifTerm isIntegerTy (coerceShow$ \(a::Integer)->a) ] - where ifTerm pred f p t = if pred t then liftM Just (f p t) else return Nothing - isIntegerDC Term{dc=dc} = - dataConName dc `elem` [ smallIntegerDataConName - , largeIntegerDataConName] - isTupleDC Term{dc=dc} = dc `elem` snd (unzip (elems boxedTupleArr)) - isDC a_dc Term{dc=dc} = a_dc == dc + where ifTerm pred f p t@Term{} | pred t = liftM Just (f p t) + | otherwise = return Nothing + isIntegerTy Term{ty=ty} | Just (tc,_) <- splitTyConApp_maybe ty + = tyConName tc == integerTyConName + isTupleTy Term{ty=ty} | Just (tc,_) <- splitTyConApp_maybe ty + = tc `elem` (fst.unzip.elems) boxedTupleArr + isTyCon a_tc Term{ty=ty} | Just (tc,_) <- splitTyConApp_maybe ty + = a_tc == tc coerceShow f _ = return . text . show . f . unsafeCoerce# . val --TODO pprinting of list terms is not lazy doList p h t = do let elems = h : getListTerms t isConsLast = termType(last elems) /= termType h - print_elems <- mapM (pprP 5) elems + print_elems <- mapM (y cons_prec) elems return$ if isConsLast - then cparen (p >= 5) . hsep . punctuate (space<>colon) + then cparen (p >= cons_prec) . hsep . punctuate (space<>colon) $ print_elems else brackets (hcat$ punctuate comma print_elems) @@ -348,6 +365,7 @@ cPprTermBase pprP = getListTerms t@Suspension{} = [t] getListTerms t = pprPanic "getListTerms" (ppr t) + repPrim :: TyCon -> [Word] -> String repPrim t = rep where rep x @@ -376,9 +394,29 @@ repPrim t = rep where | t == tVarPrimTyCon = "" | otherwise = showSDoc (char '<' <> ppr t <> char '>') where build ww = unsafePerformIO $ withArray ww (peek . castPtr) +-- This ^^^ relies on the representation of Haskell heap values being +-- the same as in a C array. + ----------------------------------- -- Type Reconstruction ----------------------------------- +{- +Type Reconstruction is type inference done on heap closures. +The algorithm walks the heap generating a set of equations, which +are solved with syntactic unification. +A type reconstruction equation looks like: + + = + +The full equation set is generated by traversing all the subterms, starting +from a given term. + +The only difficult part is that newtypes are only found in the lhs of equations. +Right hand sides are missing them. We can either (a) drop them from the lhs, or +(b) reconstruct them in the rhs when possible. + +The function congruenceNewtypes takes a shot at (b) +-} -- The Type Reconstruction monad type TR a = TcM a @@ -393,88 +431,11 @@ runTR hsc_env c = do trIO :: IO a -> TR a trIO = liftTcM . ioToTcRn -addConstraint :: TcType -> TcType -> TR () -addConstraint t1 t2 = congruenceNewtypes t1 t2 >>= uncurry unifyType - -{- - A parallel fold over two Type values, - compensating for missing newtypes on both sides. - This is necessary because newtypes are not present - in runtime, but since sometimes there is evidence - available we do our best to reconstruct them. - Evidence can come from DataCon signatures or - from compile-time type inference. - I am using the words congruence and rewriting - because what we are doing here is an approximation - of unification modulo a set of equations, which would - come from newtype definitions. These should be the - equality coercions seen in System Fc. Rewriting - is performed, taking those equations as rules, - before launching unification. - - It doesn't make sense to rewrite everywhere, - or we would end up with all newtypes. So we rewrite - only in presence of evidence. - The lhs comes from the heap structure of ptrs,nptrs. - The rhs comes from a DataCon type signature. - Rewriting in the rhs is restricted to the result type. - - Note that it is very tricky to make this 'rewriting' - work with the unification implemented by TcM, where - substitutions are 'inlined'. The order in which - constraints are unified is vital for this (or I am - using TcM wrongly). --} -congruenceNewtypes :: TcType -> TcType -> TcM (TcType,TcType) -congruenceNewtypes = go True - where - go rewriteRHS lhs rhs - -- TyVar lhs inductive case - | Just tv <- getTyVar_maybe lhs - = recoverM (return (lhs,rhs)) $ do - Indirect ty_v <- readMetaTyVar tv - (lhs', rhs') <- go rewriteRHS ty_v rhs - writeMutVar (metaTvRef tv) (Indirect lhs') - return (lhs, rhs') - -- TyVar rhs inductive case - | Just tv <- getTyVar_maybe rhs - = recoverM (return (lhs,rhs)) $ do - Indirect ty_v <- readMetaTyVar tv - (lhs', rhs') <- go rewriteRHS lhs ty_v - writeMutVar (metaTvRef tv) (Indirect rhs') - return (lhs', rhs) --- FunTy inductive case - | Just (l1,l2) <- splitFunTy_maybe lhs - , Just (r1,r2) <- splitFunTy_maybe rhs - = do (l2',r2') <- go True l2 r2 - (l1',r1') <- go False l1 r1 - return (mkFunTy l1' l2', mkFunTy r1' r2') --- TyconApp Inductive case; this is the interesting bit. - | Just (tycon_l, args_l) <- splitNewTyConApp_maybe lhs - , Just (tycon_r, args_r) <- splitNewTyConApp_maybe rhs = do - - let (tycon_l',args_l') = if isNewTyCon tycon_r && not(isNewTyCon tycon_l) - then (tycon_r, rewrite tycon_r lhs) - else (tycon_l, args_l) - (tycon_r',args_r') = if rewriteRHS && isNewTyCon tycon_l && not(isNewTyCon tycon_r) - then (tycon_l, rewrite tycon_l rhs) - else (tycon_r, args_r) - (args_l'', args_r'') <- unzip `liftM` zipWithM (go rewriteRHS) args_l' args_r' - return (mkTyConApp tycon_l' args_l'', mkTyConApp tycon_r' args_r'') - - | otherwise = return (lhs,rhs) - - where rewrite newtyped_tc lame_tipe - | (tvs, tipe) <- newTyConRep newtyped_tc - = case tcUnifyTys (const BindMe) [tipe] [lame_tipe] of - Just subst -> substTys subst (map mkTyVarTy tvs) - otherwise -> panic "congruenceNewtypes: Can't unify a newtype" +liftTcM = id newVar :: Kind -> TR TcTyVar newVar = liftTcM . newFlexiTyVar -liftTcM = id - -- | Returns the instantiated type scheme ty', and the substitution sigma -- such that sigma(ty') = ty instScheme :: Type -> TR (TcType, TvSubst) @@ -482,6 +443,17 @@ instScheme ty | (tvs, rho) <- tcSplitForAllTys ty = liftTcM$ do (tvs',theta,ty') <- tcInstType (mapM tcInstTyVar) ty return (ty', zipTopTvSubst tvs' (mkTyVarTys tvs)) +-- Adds a constraint of the form t1 == t2 +-- t1 is expected to come from walking the heap +-- t2 is expected to come from a datacon signature +-- Before unification, congruenceNewtypes needs to +-- do its magic. +addConstraint :: TcType -> TcType -> TR () +addConstraint t1 t2 = congruenceNewtypes t1 t2 >>= uncurry unifyType + + + +-- Type & Term reconstruction cvObtainTerm :: HscEnv -> Bool -> Maybe Type -> HValue -> IO Term cvObtainTerm hsc_env force mb_ty hval = runTR hsc_env $ do tv <- liftM mkTyVarTy (newVar argTypeKind) @@ -496,8 +468,9 @@ cvObtainTerm hsc_env force mb_ty hval = runTR hsc_env $ do return$ mapTermType (substTy rev_subst) term where go tv ty a = do - let monomorphic = not(isTyVarTy tv) -- This is a convention. The ancestor tests for - -- monomorphism and passes a type instead of a tv + let monomorphic = not(isTyVarTy tv) + -- This ^^^ is a convention. The ancestor tests for + -- monomorphism and passes a type instead of a tv clos <- trIO $ getClosureData a case tipe clos of -- Thunks we may want to force @@ -513,23 +486,31 @@ cvObtainTerm hsc_env force mb_ty hval = runTR hsc_env $ do case m_dc of Nothing -> panic "Can't find the DataCon for a term" Just dc -> do - let extra_args = length(dataConRepArgTys dc) - length(dataConOrigArgTys dc) + let extra_args = length(dataConRepArgTys dc) - + length(dataConOrigArgTys dc) subTtypes = matchSubTypes dc ty (subTtypesP, subTtypesNP) = partition isPointed subTtypes subTermTvs <- sequence - [ if isMonomorphic t then return t else (mkTyVarTy `fmap` newVar k) + [ if isMonomorphic t then return t + else (mkTyVarTy `fmap` newVar k) | (t,k) <- zip subTtypesP (map typeKind subTtypesP)] - -- It is vital for newtype reconstruction that the unification step is done - -- right here, _before_ the subterms are RTTI reconstructed. + -- It is vital for newtype reconstruction that the unification step + -- is done right here, _before_ the subterms are RTTI reconstructed when (not monomorphic) $ do - let myType = mkFunTys (reOrderTerms subTermTvs subTtypesNP subTtypes) tv - instScheme(dataConRepType dc) >>= addConstraint myType . fst - subTermsP <- sequence $ drop extra_args -- all extra arguments are pointed + let myType = mkFunTys (reOrderTerms subTermTvs + subTtypesNP + subTtypes) + tv + (signatureType,_) <- instScheme(dataConRepType dc) + addConstraint myType signatureType + subTermsP <- sequence $ drop extra_args + -- ^^^ all extra arguments are pointed [ appArr (go tv t) (ptrs clos) i | (i,tv,t) <- zip3 [0..] subTermTvs subTtypesP] let unboxeds = extractUnboxed subTtypesNP clos subTermsNP = map (uncurry Prim) (zip subTtypesNP unboxeds) - subTerms = reOrderTerms subTermsP subTermsNP (drop extra_args subTtypes) + subTerms = reOrderTerms subTermsP subTermsNP + (drop extra_args subTtypes) return (Term tv dc a subTerms) -- The otherwise case: can be a Thunk,AP,PAP,etc. otherwise -> @@ -537,9 +518,9 @@ cvObtainTerm hsc_env force mb_ty hval = runTR hsc_env $ do matchSubTypes dc ty | Just (_,ty_args) <- splitTyConApp_maybe (repType ty) - , null (dataConExTyVars dc) --TODO Handle the case of extra existential tyvars + , isVanillaDataCon dc --TODO non-vanilla case = dataConInstArgTys dc ty_args - +-- assumes that newtypes are looked ^^^ through | otherwise = dataConRepArgTys dc -- This is used to put together pointed and nonpointed subterms in the @@ -547,36 +528,46 @@ cvObtainTerm hsc_env force mb_ty hval = runTR hsc_env $ do reOrderTerms _ _ [] = [] reOrderTerms pointed unpointed (ty:tys) | isPointed ty = ASSERT2(not(null pointed) - , ptext SLIT("reOrderTerms") $$ (ppr pointed $$ ppr unpointed)) + , ptext SLIT("reOrderTerms") $$ + (ppr pointed $$ ppr unpointed)) head pointed : reOrderTerms (tail pointed) unpointed tys | otherwise = ASSERT2(not(null unpointed) - , ptext SLIT("reOrderTerms") $$ (ppr pointed $$ ppr unpointed)) + , ptext SLIT("reOrderTerms") $$ + (ppr pointed $$ ppr unpointed)) head unpointed : reOrderTerms pointed (tail unpointed) tys --- Strict application of f at index i -appArr f (Array _ _ ptrs#) (I# i#) = case indexArray# ptrs# i# of - (# e #) -> f e --- Fast, breadth-first version of obtainTerm that deals only with type reconstruction + +-- Fast, breadth-first Type reconstruction +max_depth = 10 :: Int cvReconstructType :: HscEnv -> Bool -> Maybe Type -> HValue -> IO Type cvReconstructType hsc_env force mb_ty hval = runTR hsc_env $ do tv <- liftM mkTyVarTy (newVar argTypeKind) case mb_ty of - Nothing -> search (isMonomorphic `fmap` zonkTcType tv) (++) [(tv, hval)] >> - zonkTcType tv -- TODO untested! + Nothing -> do search (isMonomorphic `fmap` zonkTcType tv) + (uncurry go) + [(tv, hval)] + max_depth + zonkTcType tv -- TODO untested! Just ty | isMonomorphic ty -> return ty Just ty -> do (ty',rev_subst) <- instScheme (sigmaType ty) addConstraint tv ty' - search (isMonomorphic `fmap` zonkTcType tv) (++) [(tv, hval)] + search (isMonomorphic `fmap` zonkTcType tv) + (uncurry go) + [(tv, hval)] + max_depth substTy rev_subst `fmap` zonkTcType tv where -- search :: m Bool -> ([a] -> [a] -> [a]) -> [a] -> m () - search stop combine [] = return () - search stop combine ((t,a):jj) = (jj `combine`) `fmap` go t a >>= - unlessM stop . search stop combine - - -- returns unification tasks, since we are going to want a breadth-first search + search stop expand [] depth = return () + search stop expand x 0 = fail$ "Failed to reconstruct a type after " ++ + show max_depth ++ " steps" + search stop expand (x:xx) d = do + new <- expand x + unlessM stop $ search stop expand (xx ++ new) $! (pred d) + + -- returns unification tasks,since we are going to want a breadth-first search go :: Type -> HValue -> TR [(Type, HValue)] go tv a = do clos <- trIO $ getClosureData a @@ -587,21 +578,84 @@ cvReconstructType hsc_env force mb_ty hval = runTR hsc_env $ do case m_dc of Nothing -> panic "Can't find the DataCon for a term" Just dc -> do - let extra_args = length(dataConRepArgTys dc) - length(dataConOrigArgTys dc) + let extra_args = length(dataConRepArgTys dc) - + length(dataConOrigArgTys dc) subTtypes <- mapMif (not . isMonomorphic) (\t -> mkTyVarTy `fmap` newVar (typeKind t)) (dataConRepArgTys dc) - -- It is vital for newtype reconstruction that the unification step is done - -- right here, _before_ the subterms are RTTI reconstructed. - let myType = mkFunTys subTtypes tv - fst `fmap` instScheme(dataConRepType dc) >>= addConstraint myType - return $map (\(I# i#,t) -> case ptrs clos of - (Array _ _ ptrs#) -> case indexArray# ptrs# i# of - (# e #) -> (t,e)) - (drop extra_args $ zip [0..] subTtypes) + -- It is vital for newtype reconstruction that the unification step + -- is done right here, _before_ the subterms are RTTI reconstructed + let myType = mkFunTys subTtypes tv + (signatureType,_) <- instScheme(dataConRepType dc) + addConstraint myType signatureType + return $ [ appArr (\e->(t,e)) (ptrs clos) i + | (i,t) <- drop extra_args $ zip [0..] subTtypes] otherwise -> return [] +-- Dealing with newtypes +{- + A parallel fold over two Type values, + compensating for missing newtypes on both sides. + This is necessary because newtypes are not present + in runtime, but since sometimes there is evidence + available we do our best to reconstruct them. + Evidence can come from DataCon signatures or + from compile-time type inference. + I am using the words congruence and rewriting + because what we are doing here is an approximation + of unification modulo a set of equations, which would + come from newtype definitions. These should be the + equality coercions seen in System Fc. Rewriting + is performed, taking those equations as rules, + before launching unification. + + It doesn't make sense to rewrite everywhere, + or we would end up with all newtypes. So we rewrite + only in presence of evidence. + The lhs comes from the heap structure of ptrs,nptrs. + The rhs comes from a DataCon type signature. + Rewriting in the rhs is restricted to the result type. + + Note that it is very tricky to make this 'rewriting' + work with the unification implemented by TcM, where + substitutions are 'inlined'. The order in which + constraints are unified is vital for this (or I am + using TcM wrongly). +-} +congruenceNewtypes :: TcType -> TcType -> TcM (TcType,TcType) +congruenceNewtypes lhs rhs + -- TyVar lhs inductive case + | Just tv <- getTyVar_maybe lhs + = recoverM (return (lhs,rhs)) $ do + Indirect ty_v <- readMetaTyVar tv + (lhs1, rhs1) <- congruenceNewtypes ty_v rhs + return (lhs, rhs1) +-- FunTy inductive case + | Just (l1,l2) <- splitFunTy_maybe lhs + , Just (r1,r2) <- splitFunTy_maybe rhs + = do (l2',r2') <- congruenceNewtypes l2 r2 + (l1',r1') <- congruenceNewtypes l1 r1 + return (mkFunTy l1' l2', mkFunTy r1' r2') +-- TyconApp Inductive case; this is the interesting bit. + | Just (tycon_l, args_l) <- splitNewTyConApp_maybe lhs + , Just (tycon_r, args_r) <- splitNewTyConApp_maybe rhs + , tycon_l /= tycon_r + = return (lhs, upgrade tycon_l rhs) + + | otherwise = return (lhs,rhs) + + where upgrade :: TyCon -> Type -> Type + upgrade new_tycon ty + | not (isNewTyCon new_tycon) = ty + | ty' <- mkTyConApp new_tycon (map mkTyVarTy $ tyConTyVars new_tycon) + , Just subst <- tcUnifyTys (const BindMe) [ty] [repType ty'] + = substTy subst ty' + -- assumes that reptype doesn't touch tyconApp args ^^^ + + +-------------------------------------------------------------------------------- + isMonomorphic ty | (tvs, ty') <- splitForAllTys ty = null tvs && (isEmptyVarSet . tyVarsOfType) ty' @@ -612,6 +666,10 @@ mapMif_ pred f (x:xx) = (if pred x then f x else return x) : mapMif_ pred f xx unlessM condM acc = condM >>= \c -> unless c acc +-- Strict application of f at index i +appArr f (Array _ _ ptrs#) (I# i#) = case indexArray# ptrs# i# of + (# e #) -> f e + zonkTerm :: Term -> TcM Term zonkTerm = foldTerm idTermFoldM { fTerm = \ty dc v tt -> sequence tt >>= \tt -> @@ -625,53 +683,4 @@ zonkTerm = foldTerm idTermFoldM { -- Generalize the type: find all free tyvars and wrap in the appropiate ForAll. sigmaType ty = mkForAllTys (varSetElems$ tyVarsOfType (dropForAlls ty)) ty -{- -Example of Type Reconstruction --------------------------------- -Suppose we have an existential type such as - -data Opaque = forall a. Opaque a - -And we have a term built as: - -t = Opaque (map Just [[1,1],[2,2]]) -The type of t as far as the typechecker goes is t :: Opaque -If we seq the head of t, we obtain: - -t - O (_1::a) - -seq _1 () - -t - O ( (_3::b) : (_4::[b]) ) - -seq _3 () - -t - O ( (Just (_5::c)) : (_4::[b]) ) - -At this point, we know that b = (Maybe c) - -seq _5 () - -t - O ( (Just ((_6::d) : (_7::[d]) )) : (_4::[b]) ) - -At this point, we know that c = [d] - -seq _6 () - -t - O ( (Just (1 : (_7::[d]) )) : (_4::[b]) ) - -At this point, we know that d = Integer - -The fully reconstructed expressions, with propagation, would be: - -t - O ( (Just (_5::c)) : (_4::[Maybe c]) ) -t - O ( (Just ((_6::d) : (_7::[d]) )) : (_4::[Maybe [d]]) ) -t - O ( (Just (1 : (_7::[Integer]) )) : (_4::[Maybe [Integer]]) ) - - -For reference, the type of the thing inside the opaque is -map Just [[1,1],[2,2]] :: [Maybe [Integer]] - -NOTE: (Num t) contexts have been manually replaced by Integer for clarity --}