+ | isPointed ty = ASSERT2(not(null pointed)
+ , ptext (sLit "reOrderTerms") $$
+ (ppr pointed $$ ppr unpointed))
+ let (t:tt) = pointed in t : reOrderTerms tt unpointed tys
+ | otherwise = ASSERT2(not(null unpointed)
+ , ptext (sLit "reOrderTerms") $$
+ (ppr pointed $$ ppr unpointed))
+ let (t:tt) = unpointed in t : reOrderTerms pointed tt tys
+
+ expandNewtypes t@Term{ ty=ty, subTerms=tt }
+ | Just (tc, args) <- splitNewTyConApp_maybe ty
+ , isNewTyCon tc
+ , wrapped_type <- newTyConInstRhs tc args
+ , Just dc <- maybeTyConSingleCon tc
+ , t' <- expandNewtypes t{ ty = wrapped_type
+ , subTerms = map expandNewtypes tt }
+ = NewtypeWrap ty (Right dc) t'
+
+ | otherwise = t{ subTerms = map expandNewtypes tt }
+
+ expandNewtypes t = t
+
+
+-- Fast, breadth-first Type reconstruction
+cvReconstructType :: HscEnv -> Int -> Maybe Type -> HValue -> IO (Maybe Type)
+cvReconstructType hsc_env max_depth mb_ty hval = runTR_maybe hsc_env $ do
+ tv <- newVar argTypeKind
+ case mb_ty of
+ Nothing -> do search (isMonomorphic `fmap` zonkTcType tv)
+ (uncurry go)
+ (Seq.singleton (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)
+ (\(ty,a) -> go ty a)
+ (Seq.singleton (tv, hval))
+ max_depth
+ substTy rev_subst `fmap` zonkTcType tv
+ where
+-- search :: m Bool -> ([a] -> [a] -> [a]) -> [a] -> m ()
+ search _ _ _ 0 = traceTR (text "Failed to reconstruct a type after " <>
+ int max_depth <> text " steps")
+ search stop expand l d =
+ case viewl l of
+ EmptyL -> return ()
+ x :< xx -> unlessM stop $ do
+ new <- expand x
+ search stop expand (xx `mappend` Seq.fromList 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
+ case tipe clos of
+ Indirection _ -> go tv $! (ptrs clos ! 0)
+ MutVar _ -> do
+ contents <- trIO$ IO$ \w -> readMutVar# (unsafeCoerce# a) w
+ tv' <- newVar liftedTypeKind
+ world <- newVar liftedTypeKind
+ addConstraint tv (mkTyConApp mutVarPrimTyCon [world,tv'])
+-- x <- go tv' ty_contents contents
+ return [(tv', contents)]
+ Constr -> do
+ Right dcname <- dataConInfoPtrToName (infoPtr clos)
+ (_,mb_dc) <- tryTcErrs (tcLookupDataCon dcname)
+ case mb_dc of
+ Nothing-> do
+ -- TODO: Check this case
+ forM [0..length (elems $ ptrs clos)] $ \i -> do
+ tv <- newVar liftedTypeKind
+ return$ appArr (\e->(tv,e)) (ptrs clos) i
+
+ Just dc -> do
+ let extra_args = length(dataConRepArgTys dc) -
+ length(dataConOrigArgTys dc)
+ subTtypes <- mapMif (not . isMonomorphic)
+ (\t -> 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
+ (signatureType,_) <- instScheme(dataConRepType dc)
+ addConstraint myType signatureType
+ return $ [ appArr (\e->(t,e)) (ptrs clos) i
+ | (i,t) <- drop extra_args $
+ zip [0..] (filter isPointed subTtypes)]
+ _ -> return []
+
+-- Compute the difference between a base type and the type found by RTTI
+-- improveType <base_type> <rtti_type>
+-- The types can contain skolem type variables, which need to be treated as normal vars.
+-- In particular, we want them to unify with things.
+improveRTTIType :: HscEnv -> Type -> Type -> IO (Maybe TvSubst)
+improveRTTIType hsc_env ty rtti_ty = runTR_maybe hsc_env $ do
+ let (_,ty0) = splitForAllTys ty
+ ty_tvs = varSetElems $ tyVarsOfType ty0
+ let (_,rtti_ty0)= splitForAllTys rtti_ty
+ rtti_tvs = varSetElems $ tyVarsOfType rtti_ty0
+ (ty_tvs',_,ty')<- tcInstType (mapM tcInstTyVar) (mkSigmaTy ty_tvs [] ty0)
+ (_,_,rtti_ty') <- tcInstType (mapM tcInstTyVar) (mkSigmaTy rtti_tvs [] rtti_ty0)
+ boxyUnify rtti_ty' ty'
+ tvs1_contents <- zonkTcTyVars ty_tvs'
+ let subst = uncurry zipTopTvSubst
+ (unzip [(tv,ty) | tv <- ty_tvs, ty <- tvs1_contents
+ , getTyVar_maybe ty /= Just tv
+ , not(isTyVarTy ty)])
+-- liftIO $ hPutStrLn stderr $ showSDocDebug $ text "unify " <+> sep [ppr ty, ppr rtti_ty, equals, ppr subst ]
+ return subst
+
+-- Dealing with newtypes
+{-
+ congruenceNewtypes does 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 sometimes there is evidence available.
+ Evidence can come from DataCon signatures or
+ from compile-time type inference.
+ What we are doing here is an approximation
+ of unification modulo a set of equations derived
+ from newtype definitions. These equations should be the
+ same as the equality coercions generated for newtypes
+ in System Fc. The idea is to perform a sort of rewriting,
+ taking those equations as rules, before launching unification.
+
+ The caller must ensure the following.
+ The 1st type (lhs) comes from the heap structure of ptrs,nptrs.
+ The 2nd type (rhs) comes from a DataCon type signature.
+ Rewriting (i.e. adding/removing a newtype wrapper) can happen
+ in both types, but in the rhs it 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 operationally inlined. The order in which
+ constraints are unified is vital as we cannot modify
+ anything that has been touched by a previous unification step.
+Therefore, congruenceNewtypes is sound only if the types
+recovered by the RTTI mechanism are unified Top-Down.
+-}
+congruenceNewtypes :: TcType -> TcType -> TR (TcType,TcType)
+congruenceNewtypes lhs rhs
+ -- TyVar lhs inductive case
+ | Just tv <- getTyVar_maybe lhs
+ = recoverTc (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, _) <- splitNewTyConApp_maybe lhs
+ , Just (tycon_r, _) <- splitNewTyConApp_maybe rhs
+ , tycon_l /= tycon_r
+ = do rhs' <- upgrade tycon_l rhs
+ return (lhs, rhs')
+
+ | otherwise = return (lhs,rhs)
+
+ where upgrade :: TyCon -> Type -> TR Type
+ upgrade new_tycon ty
+ | not (isNewTyCon new_tycon) = return ty
+ | otherwise = do
+ vars <- mapM (newVar . tyVarKind) (tyConTyVars new_tycon)
+ let ty' = mkTyConApp new_tycon vars
+ liftTcM (unifyType ty (repType ty'))
+ -- assumes that reptype doesn't ^^^^ touch tyconApp args
+ return ty'
+
+
+--------------------------------------------------------------------------------
+-- Semantically different to recoverM in TcRnMonad
+-- recoverM retains the errors in the first action,
+-- whereas recoverTc here does not
+recoverTc :: TcM a -> TcM a -> TcM a
+recoverTc recover thing = do
+ (_,mb_res) <- tryTcErrs thing
+ case mb_res of
+ Nothing -> recover
+ Just res -> return res
+
+isMonomorphic :: Type -> Bool
+isMonomorphic ty | (tvs, ty') <- splitForAllTys ty
+ = null tvs && (isEmptyVarSet . tyVarsOfType) ty'
+
+mapMif :: Monad m => (a -> Bool) -> (a -> m a) -> [a] -> m [a]
+mapMif pred f xx = sequence $ mapMif_ pred f xx
+ where
+ mapMif_ _ _ [] = []
+ mapMif_ pred f (x:xx) = (if pred x then f x else return x) : mapMif_ pred f xx
+
+unlessM :: Monad m => m Bool -> m () -> m ()
+unlessM condM acc = condM >>= \c -> unless c acc
+
+-- Strict application of f at index i
+appArr :: Ix i => (e -> a) -> Array i e -> Int -> a
+appArr f a@(Array _ _ _ ptrs#) i@(I# i#)
+ = ASSERT (i < length(elems a))
+ case indexArray# ptrs# i# of
+ (# e #) -> f e