@@ -0,0 +1,730 @@
1+-----------------------------------------------------------------------------
3+-- Module : Language.PureScript.TypeChecker.Types
4+-- Copyright : (c) Phil Freeman 2013
7+-- Maintainer : Phil Freeman <paf31@cantab.net>
8+-- Stability : experimental
13+-----------------------------------------------------------------------------
15+{-# LANGUAGE DeriveDataTypeable #-}
17+module Language.PureScript.TypeChecker.Types (
22+import Data.Maybe (isJust, fromMaybe)
24+import qualified Data.Data as D
25+import Data.Generics (everywhere, everywhereM, everything, mkT, mkM, mkQ, extM, extQ)
27+import Language.PureScript.Values
28+import Language.PureScript.Types
29+import Language.PureScript.Kinds
30+import Language.PureScript.Names
31+import Language.PureScript.TypeChecker.Monad
32+import Language.PureScript.TypeChecker.Kinds
33+import Language.PureScript.TypeChecker.Synonyms
34+import Language.PureScript.Pretty
35+import Language.PureScript.Unknown
37+import Control.Monad.State
38+import Control.Monad.Error
40+import Control.Applicative
41+import Control.Arrow (Arrow(..), Kleisli(..), (***), (&&&), second)
42+import qualified Control.Category as C
44+import qualified Data.Map as M
46+instance Unifiable Type where
48+ isUnknown (TUnknown u) = Just u
49+ isUnknown _ = Nothing
51+ apply s (TUnknown u) = runSubstitution s u
52+ apply s (SaturatedTypeSynonym name tys) = SaturatedTypeSynonym name $ map (apply s) tys
53+ apply s (ForAll idents ty) = ForAll idents $ apply s ty
54+ apply s (Array t) = Array (apply s t)
55+ apply s (Object r) = Object (apply s r)
56+ apply s (Function args ret) = Function (map (apply s) args) (apply s ret)
57+ apply s (TypeApp t1 t2) = TypeApp (apply s t1) (apply s t2)
59+ unknowns (TUnknown (Unknown u)) = [u]
60+ unknowns (SaturatedTypeSynonym _ tys) = concatMap unknowns tys
61+ unknowns (ForAll idents ty) = unknowns ty
62+ unknowns (Array t) = unknowns t
63+ unknowns (Object r) = unknowns r
64+ unknowns (Function args ret) = concatMap unknowns args ++ unknowns ret
65+ unknowns (TypeApp t1 t2) = unknowns t1 ++ unknowns t2
68+instance Unifiable Row where
70+ isUnknown (RUnknown u) = Just u
71+ isUnknown _ = Nothing
74+ (s1, r1') = rowToList r1
75+ (s2, r2') = rowToList r2
76+ int = [ (t1, t2) | (name, t1) <- s1, (name', t2) <- s2, name == name' ]
77+ sd1 = [ (name, t1) | (name, t1) <- s1, name `notElem` map fst s2 ]
78+ sd2 = [ (name, t2) | (name, t2) <- s2, name `notElem` map fst s1 ]
80+ forM_ int (uncurry (~~))
81+ unifyRows sd1 r1' sd2 r2'
83+ unifyRows :: [(String, Type)] -> Row -> [(String, Type)] -> Row -> Subst Check ()
84+ unifyRows [] (RUnknown u) sd r = replace u (rowFromList (sd, r))
85+ unifyRows sd r [] (RUnknown u) = replace u (rowFromList (sd, r))
86+ unifyRows ns@((name, ty):row) r others u@(RUnknown un) = do
88+ forM row $ \(_, ty) -> occursCheck un ty
90+ u ~~ RCons name ty u'
91+ unifyRows row r others u'
92+ unifyRows [] REmpty [] REmpty = return ()
93+ unifyRows [] (RowVar v1) [] (RowVar v2) | v1 == v2 = return ()
94+ unifyRows [] (RSkolem s1) [] (RSkolem s2) | s1 == s2 = return ()
95+ unifyRows sd1 r1 sd2 r2 = throwError $ "Cannot unify " ++ prettyPrintRow (rowFromList (sd1, r1)) ++ " with " ++ prettyPrintRow (rowFromList (sd2, r2)) ++ "."
96+ apply s (RUnknown u) = runSubstitution s u
97+ apply s (RCons name ty r) = RCons name (apply s ty) (apply s r)
99+ unknowns (RUnknown (Unknown u)) = [u]
100+ unknowns (RCons _ ty r) = unknowns ty ++ unknowns r
103+unifyTypes :: Type -> Type -> Subst Check ()
104+unifyTypes t1 t2 = rethrow (\e -> "Error unifying type " ++ prettyPrintType t1 ++ " with type " ++ prettyPrintType t2 ++ ":\n" ++ e) $ do
107+ unifyTypes' (TUnknown u1) (TUnknown u2) | u1 == u2 = return ()
108+ unifyTypes' (TUnknown u) t = replace u t
109+ unifyTypes' t (TUnknown u) = replace u t
110+ unifyTypes' (SaturatedTypeSynonym name1 args1) (SaturatedTypeSynonym name2 args2)
111+ | name1 == name2 = zipWithM_ unifyTypes args1 args2
112+ unifyTypes' (SaturatedTypeSynonym name args) ty = do
114+ modulePath <- checkModulePath `fmap` lift get
115+ case M.lookup (qualify modulePath name) (typeSynonyms env) of
116+ Just (synArgs, body) -> do
117+ let m = M.fromList $ zip synArgs args
118+ let replaced = replaceTypeVars m body
119+ replaced `unifyTypes` ty
120+ Nothing -> error "Type synonym was not defined"
121+ unifyTypes' ty s@(SaturatedTypeSynonym _ _) = s `unifyTypes` ty
122+ unifyTypes' (ForAll ident1 ty1) (ForAll ident2 ty2) = do
123+ sk <- skolemize ident1 ty1
124+ replaced <- replaceVarsWithUnknowns [ident2] ty2
125+ sk `unifyTypes` replaced
126+ unifyTypes' (ForAll ident ty1) ty2 = do
127+ sk <- skolemize ident ty1
129+ unifyTypes' ty f@(ForAll _ _) = f `unifyTypes` ty
130+ unifyTypes' Number Number = return ()
131+ unifyTypes' String String = return ()
132+ unifyTypes' Boolean Boolean = return ()
133+ unifyTypes' (Array s) (Array t) = s `unifyTypes` t
134+ unifyTypes' (Object row1) (Object row2) = row1 ~~ row2
135+ unifyTypes' (Function args1 ret1) (Function args2 ret2) = do
136+ guardWith "Function applied to incorrect number of args" $ length args1 == length args2
137+ zipWithM_ unifyTypes args1 args2
138+ ret1 `unifyTypes` ret2
139+ unifyTypes' (TypeVar v1) (TypeVar v2) | v1 == v2 = return ()
140+ unifyTypes' (TypeConstructor c1) (TypeConstructor c2) = do
141+ modulePath <- checkModulePath `fmap` lift get
142+ guardWith ("Cannot unify " ++ show c1 ++ " with " ++ show c2 ++ ".") (qualify modulePath c1 == qualify modulePath c2)
143+ unifyTypes' (TypeApp t1 t2) (TypeApp t3 t4) = do
146+ unifyTypes' (Skolem s1) (Skolem s2) | s1 == s2 = return ()
147+ unifyTypes' t1 t2 = throwError $ "Cannot unify " ++ prettyPrintType t1 ++ " with " ++ prettyPrintType t2 ++ "."
149+isFunction :: Value -> Bool
150+isFunction (Abs _ _) = True
151+isFunction (TypedValue untyped _) = isFunction untyped
154+typeOf :: Maybe Ident -> Value -> Check Type
156+ (ty, sub, checks) <- runSubst $ case name of
157+ Just ident | isFunction val ->
159+ ty <- infer (M.singleton ident me) val
162+ _ -> infer M.empty val
163+ escapeCheck checks ty sub
164+ return $ varIfUnknown $ desaturateAllTypeSynonyms $ setifyAll ty
166+escapeCheck :: [AnyUnifiable] -> Type -> Substitution -> Check ()
167+escapeCheck checks ty sub =
169+ visibleUnknowns = nub $ unknowns ty
171+ forM_ checks $ \check -> case check of
172+ AnyUnifiable t -> do
173+ let unsolvedUnknowns = nub . unknowns $ apply sub t
174+ guardWith "Escape check fails" $ null $ unsolvedUnknowns \\ visibleUnknowns
177+setify = rowFromList . first (M.toList . M.fromList) . rowToList
179+setifyAll :: (D.Data d) => d -> d
180+setifyAll = everywhere (mkT setify)
182+findTypeVars :: (D.Data d) => d -> [String]
183+findTypeVars = everything (++) (mkQ [] f)
185+ f :: Type -> [String]
189+varIfUnknown :: Type -> Type
192+ (ty', m) = flip runState M.empty $ everywhereM (flip extM g $ mkM f) ty
194+ mkForAll (sort $ nub $ M.elems m ++ findTypeVars ty) ty'
196+ f :: Type -> State (M.Map Int String) Type
197+ f (TUnknown (Unknown n)) = do
199+ case M.lookup n m of
201+ let name = 't' : show (M.size m)
202+ put $ M.insert n name m
203+ return $ TypeVar name
204+ Just name -> return $ TypeVar name
206+ g :: Row -> State (M.Map Int String) Row
207+ g (RUnknown (Unknown n)) = do
209+ case M.lookup n m of
211+ let name = 'r' : show (M.size m)
212+ put $ M.insert n name m
213+ return $ RowVar name
214+ Just name -> return $ RowVar name
217+replaceTypeVars :: M.Map String Type -> Type -> Type
218+replaceTypeVars m = everywhere (mkT replace)
220+ replace (TypeVar v) = case M.lookup v m of
225+replaceRowVars :: M.Map String Row -> Type -> Type
226+replaceRowVars m = everywhere (mkT replace)
228+ replace (RowVar v) = case M.lookup v m of
233+replaceVarsWithUnknowns :: [String] -> Type -> Subst Check Type
234+replaceVarsWithUnknowns idents = flip evalStateT M.empty . everywhereM (flip extM f $ mkM g)
236+ f :: Type -> StateT (M.Map String Int) (Subst Check) Type
237+ f (TypeVar var) | var `elem` idents = do
240+ case M.lookup var m of
242+ put (M.insert var n m)
243+ return $ TUnknown (Unknown n)
244+ Just u -> return $ TUnknown (Unknown u)
246+ g :: Row -> StateT (M.Map String Int) (Subst Check) Row
247+ g (RowVar var) | var `elem` idents = do
250+ case M.lookup var m of
252+ put (M.insert var n m)
253+ return $ RUnknown (Unknown n)
254+ Just u -> return $ RUnknown (Unknown u)
257+replaceAllTypeSynonyms :: (D.Data d) => d -> Check d
258+replaceAllTypeSynonyms d = do
260+ let syns = map (\((path, name), (args, _)) -> (Qualified path name, length args)) . M.toList $ typeSynonyms env
261+ either throwError return $ saturateAllTypeSynonyms syns d
263+desaturateAllTypeSynonyms :: (D.Data d) => d -> d
264+desaturateAllTypeSynonyms = everywhere (mkT replace)
266+ replace (SaturatedTypeSynonym name args) = foldl TypeApp (TypeConstructor name) args
269+ensureNoDuplicateProperties :: [(String, Value)] -> Check ()
270+ensureNoDuplicateProperties ps = guardWith "Duplicate property names" $ length (nub . map fst $ ps) == length ps
272+infer :: M.Map Ident Type -> Value -> Subst Check Type
273+infer m val = rethrow (\e -> "Error inferring type of term " ++ prettyPrintValue val ++ ":\n" ++ e) $ do
278+infer' _ (NumericLiteral _) = return Number
279+infer' _ (StringLiteral _) = return String
280+infer' _ (BooleanLiteral _) = return Boolean
281+infer' m (ArrayLiteral vals) = do
282+ ts <- mapM (infer m) vals
284+ forM_ ts $ \t -> arr ~~ Array t
286+infer' m (Unary op val) = do
289+infer' m (Binary op left right) = do
292+ inferBinary op t1 t2
293+infer' m (ObjectLiteral ps) = do
294+ lift $ ensureNoDuplicateProperties ps
295+ ts <- mapM (infer m . snd) ps
296+ let fields = zipWith (\(name, _) t -> (name, t)) ps ts
297+ return $ Object $ typesToRow fields
298+infer' m (ObjectUpdate o ps) = do
299+ lift $ ensureNoDuplicateProperties ps
302+ ts <- mapM (infer m . snd) ps
303+ let tys = zipWith (\(name, _) t -> (name, t)) ps ts
304+ obj ~~ Object (rowFromList (tys, row))
306+infer' m (Indexer index val) = do
308+ check m index Number
309+ check m val (Array el)
311+infer' m (Accessor prop val) = do
314+ check m val (Object (RCons prop field rest))
316+infer' m (Abs args ret) = do
317+ ts <- replicateM (length args) fresh
318+ let m' = m `M.union` M.fromList (zip args ts)
319+ body <- infer m' ret
320+ return $ Function ts body
321+infer' m (App f xs) = do
324+ checkFunctionApplication m t1 xs ret
326+infer' m (Var var@(Qualified mp name)) = do
329+ case M.lookup name m of
330+ Just ty -> lift $ replaceAllTypeSynonyms ty
331+ Nothing -> lookupGlobal
336+ modulePath <- checkModulePath `fmap` lift get
337+ case M.lookup (qualify modulePath var) (names env) of
338+ Nothing -> throwError $ show var ++ " is undefined"
339+ Just (ty, _) -> lift $ replaceAllTypeSynonyms ty
340+infer' m (Block ss) = do
342+ (allCodePathsReturn, _) <- checkBlock m M.empty ret ss
343+ guardWith "Block is missing a return statement" allCodePathsReturn
345+infer' m (Constructor c) = do
347+ modulePath <- checkModulePath `fmap` lift get
348+ case M.lookup (qualify modulePath c) (dataConstructors env) of
349+ Nothing -> throwError $ "Constructor " ++ show c ++ " is undefined"
350+ Just ty -> lift $ replaceAllTypeSynonyms ty
351+infer' m (Case val binders) = do
354+ checkBinders m t1 ret binders
356+infer' m (IfThenElse cond th el) = do
357+ check m cond Boolean
362+infer' m (TypedValue val ty) = do
363+ kind <- lift $ kindOf ty
364+ guardWith ("Expected type of kind *, was " ++ prettyPrintKind kind) $ kind == Star
365+ ty' <- lift $ replaceAllTypeSynonyms ty
369+inferUnary :: UnaryOperator -> Type -> Subst Check Type
371+ case fromMaybe (error "Invalid operator") $ lookup op unaryOps of
372+ (valTy, resTy) -> do
376+checkUnary :: M.Map Ident Type -> UnaryOperator -> Value -> Type -> Subst Check ()
377+checkUnary m op val res =
378+ case fromMaybe (error "Invalid operator") $ lookup op unaryOps of
379+ (valTy, resTy) -> do
383+unaryOps :: [(UnaryOperator, (Type, Type))]
384+unaryOps = [ (Negate, (Number, Number))
385+ , (Not, (Boolean, Boolean))
386+ , (BitwiseNot, (Number, Number))
389+inferBinary :: BinaryOperator -> Type -> Type -> Subst Check Type
390+inferBinary op left right | isEqualityTest op = do
393+inferBinary op left right =
394+ case fromMaybe (error "Invalid operator") $ lookup op binaryOps of
395+ (valTy, resTy) -> do
400+checkBinary :: M.Map Ident Type -> BinaryOperator -> Value -> Value -> Type -> Subst Check ()
401+checkBinary m op left right res | isEqualityTest op = do
406+checkBinary m op left right res =
407+ case fromMaybe (error "Invalid operator") $ lookup op binaryOps of
408+ (valTy, resTy) -> do
413+isEqualityTest :: BinaryOperator -> Bool
414+isEqualityTest EqualTo = True
415+isEqualityTest NotEqualTo = True
416+isEqualityTest _ = False
418+binaryOps :: [(BinaryOperator, (Type, Type))]
419+binaryOps = [ (Add, (Number, Number))
420+ , (Subtract, (Number, Number))
421+ , (Multiply, (Number, Number))
422+ , (Divide, (Number, Number))
423+ , (Modulus, (Number, Number))
424+ , (BitwiseAnd, (Number, Number))
425+ , (BitwiseOr, (Number, Number))
426+ , (BitwiseXor, (Number, Number))
427+ , (ShiftRight, (Number, Number))
428+ , (ZeroFillShiftRight, (Number, Number))
429+ , (And, (Boolean, Boolean))
430+ , (Or, (Boolean, Boolean))
431+ , (Concat, (String, String))
432+ , (Modulus, (Number, Number))
433+ , (LessThan, (Number, Boolean))
434+ , (LessThanOrEqualTo, (Number, Boolean))
435+ , (GreaterThan, (Number, Boolean))
436+ , (GreaterThanOrEqualTo, (Number, Boolean))
439+inferBinder :: Type -> Binder -> Subst Check (M.Map Ident Type)
440+inferBinder _ NullBinder = return M.empty
441+inferBinder val (StringBinder _) = val ~~ String >> return M.empty
442+inferBinder val (NumberBinder _) = val ~~ Number >> return M.empty
443+inferBinder val (BooleanBinder _) = val ~~ Boolean >> return M.empty
444+inferBinder val (VarBinder name) = return $ M.singleton name val
445+inferBinder val (NullaryBinder ctor) = do
447+ modulePath <- checkModulePath `fmap` lift get
448+ case M.lookup (qualify modulePath ctor) (dataConstructors env) of
452+ _ -> throwError $ "Constructor " ++ show ctor ++ " is not defined"
453+inferBinder val (UnaryBinder ctor binder) = do
455+ modulePath <- checkModulePath `fmap` lift get
456+ case M.lookup (qualify modulePath ctor) (dataConstructors env) of
459+ ty `subsumes` (Function [obj] val)
460+ inferBinder obj binder
461+ _ -> throwError $ "Constructor " ++ show ctor ++ " is not defined"
462+inferBinder val (ObjectBinder props) = do
465+ m1 <- inferRowProperties row rest props
469+ inferRowProperties :: Row -> Row -> [(String, Binder)] -> Subst Check (M.Map Ident Type)
470+ inferRowProperties nrow row [] = nrow ~~ row >> return M.empty
471+ inferRowProperties nrow row ((name, binder):binders) = do
473+ m1 <- inferBinder propTy binder
474+ m2 <- inferRowProperties nrow (RCons name propTy row) binders
475+ return $ m1 `M.union` m2
476+inferBinder val (ArrayBinder binders rest) = do
478+ m1 <- M.unions <$> mapM (inferBinder el) binders
481+ Nothing -> return m1
483+ m2 <- inferBinder val binder
484+ return $ m1 `M.union` m2
485+inferBinder val (NamedBinder name binder) = do
486+ m <- inferBinder val binder
487+ return $ M.insert name val m
489+inferGuardedBinder :: M.Map Ident Type -> Type -> Binder -> Subst Check (M.Map Ident Type)
490+inferGuardedBinder m val (GuardedBinder cond binder) = do
491+ m1 <- inferBinder val binder
492+ ty <- infer (m `M.union` m1) cond
495+inferGuardedBinder m val b = inferBinder val b
497+checkBinders :: M.Map Ident Type -> Type -> Type -> [(Binder, Value)] -> Subst Check ()
498+checkBinders _ _ _ [] = return ()
499+checkBinders m nval ret ((binder, val):bs) = do
500+ m1 <- inferGuardedBinder m nval binder
501+ check (m `M.union` m1) val ret
502+ checkBinders m nval ret bs
504+assignVariable :: Ident -> M.Map Ident Type -> Subst Check ()
505+assignVariable name m =
506+ case M.lookup name m of
507+ Nothing -> return ()
508+ Just _ -> throwError $ "Variable with name " ++ show name ++ " already exists."
510+checkStatement :: M.Map Ident Type -> M.Map Ident Type -> Type -> Statement -> Subst Check (Bool, M.Map Ident Type)
511+checkStatement m mass ret (VariableIntroduction name val) = do
512+ assignVariable name (m `M.union` mass)
514+ return (False, M.insert name t mass)
515+checkStatement m mass ret (Assignment ident val) = do
517+ case M.lookup ident mass of
518+ Nothing -> throwError $ "No local variable with name " ++ show ident
519+ Just ty -> do t ~~ ty
520+ return (False, mass)
521+checkStatement m mass ret (While val inner) = do
523+ (allCodePathsReturn, _) <- checkBlock m mass ret inner
524+ return (allCodePathsReturn, mass)
525+checkStatement m mass ret (If ifst) = do
526+ allCodePathsReturn <- checkIfStatement m mass ret ifst
527+ return (allCodePathsReturn, mass)
528+checkStatement m mass ret (For ident start end inner) = do
529+ assignVariable ident (m `M.union` mass)
530+ check (m `M.union` mass) start Number
531+ check (m `M.union` mass) end Number
532+ let mass1 = M.insert ident Number mass
533+ (allCodePathsReturn, _) <- checkBlock (m `M.union` mass1) mass1 ret inner
534+ return (allCodePathsReturn, mass)
535+checkStatement m mass ret (ForEach ident vals inner) = do
536+ assignVariable ident (m `M.union` mass)
538+ check (m `M.union` mass) vals (Array val)
539+ let mass1 = M.insert ident val mass
540+ (allCodePathsReturn, _) <- checkBlock (m `M.union` mass1) mass1 ret inner
541+ guardWith "Cannot return from within a foreach block" $ not allCodePathsReturn
542+ return (False, mass)
543+checkStatement m mass ret (Return val) = do
544+ check (m `M.union` mass) val ret
547+checkIfStatement :: M.Map Ident Type -> M.Map Ident Type -> Type -> IfStatement -> Subst Check Bool
548+checkIfStatement m mass ret (IfStatement val thens Nothing) = do
550+ _ <- checkBlock m mass ret thens
552+checkIfStatement m mass ret (IfStatement val thens (Just elses)) = do
554+ (allCodePathsReturn1, _) <- checkBlock m mass ret thens
555+ allCodePathsReturn2 <- checkElseStatement m mass ret elses
556+ return $ allCodePathsReturn1 && allCodePathsReturn2
558+checkElseStatement :: M.Map Ident Type -> M.Map Ident Type -> Type -> ElseStatement -> Subst Check Bool
559+checkElseStatement m mass ret (Else elses) = fst <$> checkBlock m mass ret elses
560+checkElseStatement m mass ret (ElseIf ifst) = checkIfStatement m mass ret ifst
562+checkBlock :: M.Map Ident Type -> M.Map Ident Type -> Type -> [Statement] -> Subst Check (Bool, M.Map Ident Type)
563+checkBlock _ mass _ [] = return (False, mass)
564+checkBlock m mass ret (s:ss) = do
565+ (b1, mass1) <- checkStatement (m `M.union` mass) mass ret s
567+ (True, []) -> return (True, mass1)
568+ (True, _) -> throwError "Unreachable code"
570+ (b2, mass2) <- checkBlock m mass1 ret ss
573+skolemize :: String -> Type -> Subst Check Type
574+skolemize ident ty = do
575+ tsk <- Skolem <$> fresh'
576+ rsk <- RSkolem <$> fresh'
577+ return $ replaceRowVars (M.singleton ident rsk) $ replaceTypeVars (M.singleton ident tsk) ty
579+check :: M.Map Ident Type -> Value -> Type -> Subst Check ()
580+check m val ty = rethrow errorMessage $ check' m val ty
583+ "Error checking type of term " ++
584+ prettyPrintValue val ++
586+ prettyPrintType ty ++
590+check' :: M.Map Ident Type -> Value -> Type -> Subst Check ()
591+check' m val (ForAll idents ty) = do
592+ sk <- skolemize idents ty
594+check' m val (SaturatedTypeSynonym name args) = do
596+ modulePath <- checkModulePath `fmap` lift get
597+ case M.lookup (qualify modulePath name) (typeSynonyms env) of
598+ Just (synArgs, body) -> do
599+ let replaced = replaceTypeVars (M.fromList (zip synArgs args)) body
600+ check m val replaced
601+ Nothing -> error "Type synonym was not defined"
602+check' m val u@(TUnknown _) = do
605+check' m (NumericLiteral _) Number = return ()
606+check' m (StringLiteral _) String = return ()
607+check' m (BooleanLiteral _) Boolean = return ()
608+check' m (Unary op val) ty = checkUnary m op val ty
609+check' m (Binary op left right) ty = checkBinary m op left right ty
610+check' m (ArrayLiteral vals) (Array ty) = forM_ vals (\val -> check m val ty)
611+check' m (Indexer index vals) ty = check m index Number >> check m vals (Array ty)
612+check' m (Abs args ret) (Function argTys retTy) = do
613+ guardWith "Incorrect number of function arguments" (length args == length argTys)
614+ let bindings = M.fromList (zip args argTys)
615+ check (bindings `M.union` m) ret retTy
616+check' m (App f xs) ret = do
618+ checkFunctionApplication m ft xs ret
619+check' m v@(Var var@(Qualified mp name)) ty = do
622+ case M.lookup name m of
624+ repl <- lift $ replaceAllTypeSynonyms ty1
626+ Nothing -> lookupGlobal
631+ modulePath <- checkModulePath `fmap` lift get
632+ case M.lookup (qualify modulePath var) (names env) of
633+ Nothing -> throwError $ show var ++ " is undefined"
635+ repl <- lift $ replaceAllTypeSynonyms ty1
637+check' m (TypedValue val ty1) ty2 = do
638+ kind <- lift $ kindOf ty1
639+ guardWith ("Expected type of kind *, was " ++ prettyPrintKind kind) $ kind == Star
642+check' m (Case val binders) ret = do
644+ checkBinders m t1 ret binders
645+check' m (IfThenElse cond th el) ty = do
646+ check m cond Boolean
649+check' m (ObjectLiteral ps) (Object row) = do
650+ lift $ ensureNoDuplicateProperties ps
651+ checkProperties m ps row False
652+check' m (ObjectUpdate obj ps) objTy@(Object row) = do
653+ lift $ ensureNoDuplicateProperties ps
655+ checkProperties m ps row True
656+check' m (Accessor prop val) ty = do
658+ check m val (Object (RCons prop ty rest))
659+check' m (Block ss) ret = do
660+ (allCodePathsReturn, _) <- checkBlock m M.empty ret ss
661+ guardWith "Block is missing a return statement" allCodePathsReturn
662+check' m (Constructor c) ty = do
664+ modulePath <- checkModulePath `fmap` lift get
665+ case M.lookup (qualify modulePath c) (dataConstructors env) of
666+ Nothing -> throwError $ "Constructor " ++ show c ++ " is undefined"
668+ repl <- lift $ replaceAllTypeSynonyms ty1
670+check' _ val ty = throwError $ prettyPrintValue val ++ " does not have type " ++ prettyPrintType ty
672+checkProperties :: M.Map Ident Type -> [(String, Value)] -> Row -> Bool -> Subst Check ()
673+checkProperties m ps row lax = let (ts, r') = rowToList row in go ps ts r' where
674+ go [] [] REmpty = return ()
675+ go [] [] u@(RUnknown _) = u ~~ REmpty
676+ go [] [] (RSkolem _) | lax = return ()
677+ go [] ((p, _): _) _ | lax = return ()
678+ | otherwise = throwError $ prettyPrintValue (ObjectLiteral ps) ++ " does not have property " ++ p
679+ go ((p,_):_) [] REmpty = throwError $ "Property " ++ p ++ " is not present in closed object type " ++ prettyPrintRow row
680+ go ((p,v):ps) [] u@(RUnknown _) = do
683+ u ~~ RCons p ty rest
685+ go ((p,v):ps) ts r =
690+ r ~~ RCons p ty rest
694+ go ps (delete (p, ty) ts) r
695+ go _ _ _ = throwError $ prettyPrintValue (ObjectLiteral ps) ++ " does not have type " ++ prettyPrintType (Object row)
697+checkFunctionApplication :: M.Map Ident Type -> Type -> [Value] -> Type -> Subst Check ()
698+checkFunctionApplication m fnTy args ret = rethrow errorMessage $ checkFunctionApplication' m fnTy args ret
700+ errorMessage msg = "Error applying function of type "
701+ ++ prettyPrintType fnTy
702+ ++ " to arguments " ++ intercalate ", " (map prettyPrintValue args)
703+ ++ ", expecting value of type "
704+ ++ prettyPrintType ret ++ ":\n" ++ msg
706+checkFunctionApplication' :: M.Map Ident Type -> Type -> [Value] -> Type -> Subst Check ()
707+checkFunctionApplication' m (Function argTys retTy) args ret = do
708+ guardWith "Incorrect number of function arguments" (length args == length argTys)
709+ zipWithM (check m) args argTys
710+ retTy `subsumes` ret
711+checkFunctionApplication' m (ForAll ident ty) args ret = do
712+ replaced <- replaceVarsWithUnknowns [ident] ty
713+ checkFunctionApplication m replaced args ret
714+checkFunctionApplication' m u@(TUnknown _) args ret = do
715+ tyArgs <- mapM (infer m) args
716+ u `subsumes` Function tyArgs ret
717+checkFunctionApplication' _ fnTy args ret = throwError $ "Cannot apply function of type "
718+ ++ prettyPrintType fnTy
719+ ++ " to arguments " ++ intercalate ", " (map prettyPrintValue args)
720+ ++ ". Expecting value of type " ++ prettyPrintType ret ++ "."
722+subsumes :: Type -> Type -> Subst Check ()
723+subsumes (ForAll ident ty1) ty2 = do
724+ replaced <- replaceVarsWithUnknowns [ident] ty1
725+ replaced `subsumes` ty2
726+subsumes (Function args1 ret1) (Function args2 ret2) = do
727+ zipWithM subsumes args2 args1
728+ ret1 `subsumes` ret2
729+subsumes ty1 ty2 = ty1 ~~ ty2