@@ -0,0 +1,752 @@
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
113+ ty1 <- expandTypeSynonym name args
115+ unifyTypes' ty s@(SaturatedTypeSynonym _ _) = s `unifyTypes` ty
116+ unifyTypes' (ForAll ident1 ty1) (ForAll ident2 ty2) = do
117+ sk <- skolemize ident1 ty1
118+ replaced <- replaceVarsWithUnknowns [ident2] ty2
119+ sk `unifyTypes` replaced
120+ unifyTypes' (ForAll ident ty1) ty2 = do
121+ sk <- skolemize ident ty1
123+ unifyTypes' ty f@(ForAll _ _) = f `unifyTypes` ty
124+ unifyTypes' Number Number = return ()
125+ unifyTypes' String String = return ()
126+ unifyTypes' Boolean Boolean = return ()
127+ unifyTypes' (Array s) (Array t) = s `unifyTypes` t
128+ unifyTypes' (Object row1) (Object row2) = row1 ~~ row2
129+ unifyTypes' (Function args1 ret1) (Function args2 ret2) = do
130+ guardWith "Function applied to incorrect number of args" $ length args1 == length args2
131+ zipWithM_ unifyTypes args1 args2
132+ ret1 `unifyTypes` ret2
133+ unifyTypes' (TypeVar v1) (TypeVar v2) | v1 == v2 = return ()
134+ unifyTypes' (TypeConstructor c1) (TypeConstructor c2) = do
135+ modulePath <- checkModulePath `fmap` lift get
136+ guardWith ("Cannot unify " ++ show c1 ++ " with " ++ show c2 ++ ".") (qualify modulePath c1 == qualify modulePath c2)
137+ unifyTypes' (TypeApp t1 t2) (TypeApp t3 t4) = do
140+ unifyTypes' (Skolem s1) (Skolem s2) | s1 == s2 = return ()
141+ unifyTypes' t1 t2 = throwError $ "Cannot unify " ++ prettyPrintType t1 ++ " with " ++ prettyPrintType t2 ++ "."
143+isFunction :: Value -> Bool
144+isFunction (Abs _ _) = True
145+isFunction (TypedValue untyped _) = isFunction untyped
148+typeOf :: Maybe Ident -> Value -> Check Type
150+ (ty, sub, checks) <- runSubst $ case name of
151+ Just ident | isFunction val ->
153+ TypedValue val ty -> do
154+ kind <- lift $ kindOf ty
155+ guardWith ("Expected type of kind *, was " ++ prettyPrintKind kind) $ kind == Star
156+ ty' <- lift $ replaceAllTypeSynonyms ty
157+ check (M.singleton ident ty) val ty'
161+ ty <- infer (M.singleton ident me) val
164+ _ -> infer M.empty val
165+ escapeCheck checks ty sub
166+ return $ varIfUnknown $ desaturateAllTypeSynonyms $ setifyAll ty
168+escapeCheck :: [AnyUnifiable] -> Type -> Substitution -> Check ()
169+escapeCheck checks ty sub =
171+ visibleUnknowns = nub $ unknowns ty
173+ forM_ checks $ \check -> case check of
174+ AnyUnifiable t -> do
175+ let unsolvedUnknowns = nub . unknowns $ apply sub t
176+ guardWith "Escape check fails" $ null $ unsolvedUnknowns \\ visibleUnknowns
179+setify = rowFromList . first (M.toList . M.fromList) . rowToList
181+setifyAll :: (D.Data d) => d -> d
182+setifyAll = everywhere (mkT setify)
184+varIfUnknown :: Type -> Type
185+varIfUnknown ty = mkForAll (sort . map ((:) 'u' . show) . nub $ unknowns ty) ty
187+replaceTypeVars :: M.Map String Type -> Type -> Type
188+replaceTypeVars m = everywhere (mkT replace)
190+ replace (TypeVar v) = case M.lookup v m of
195+replaceRowVars :: M.Map String Row -> Type -> Type
196+replaceRowVars m = everywhere (mkT replace)
198+ replace (RowVar v) = case M.lookup v m of
203+replaceAllVarsWithUnknowns :: Type -> Subst Check Type
204+replaceAllVarsWithUnknowns (ForAll ident ty) = replaceVarsWithUnknowns [ident] ty >>= replaceAllVarsWithUnknowns
205+replaceAllVarsWithUnknowns ty = return ty
207+-- TODO: need to be careful inside a forall, since variables might be renamed
208+replaceVarsWithUnknowns :: [String] -> Type -> Subst Check Type
209+replaceVarsWithUnknowns idents = flip evalStateT M.empty . everywhereM (flip extM f $ mkM g)
211+ f :: Type -> StateT (M.Map String Int) (Subst Check) Type
212+ f (TypeVar var) | var `elem` idents = do
215+ case M.lookup var m of
217+ put (M.insert var n m)
218+ return $ TUnknown (Unknown n)
219+ Just u -> return $ TUnknown (Unknown u)
221+ g :: Row -> StateT (M.Map String Int) (Subst Check) Row
222+ g (RowVar var) | var `elem` idents = do
225+ case M.lookup var m of
227+ put (M.insert var n m)
228+ return $ RUnknown (Unknown n)
229+ Just u -> return $ RUnknown (Unknown u)
232+replaceAllTypeSynonyms :: (D.Data d) => d -> Check d
233+replaceAllTypeSynonyms d = do
235+ let syns = map (\((path, name), (args, _)) -> (Qualified path name, length args)) . M.toList $ typeSynonyms env
236+ either throwError return $ saturateAllTypeSynonyms syns d
238+desaturateAllTypeSynonyms :: (D.Data d) => d -> d
239+desaturateAllTypeSynonyms = everywhere (mkT replace)
241+ replace (SaturatedTypeSynonym name args) = foldl TypeApp (TypeConstructor name) args
244+expandAllTypeSynonyms :: Type -> Subst Check Type
245+expandAllTypeSynonyms (SaturatedTypeSynonym name args) = expandTypeSynonym name args >>= expandAllTypeSynonyms
246+expandAllTypeSynonyms ty = return ty
248+expandTypeSynonym :: Qualified ProperName -> [Type] -> Subst Check Type
249+expandTypeSynonym name args = do
251+ modulePath <- checkModulePath `fmap` lift get
252+ case M.lookup (qualify modulePath name) (typeSynonyms env) of
253+ Just (synArgs, body) -> do
254+ let m = M.fromList $ zip synArgs args
255+ return $ replaceTypeVars m body
256+ Nothing -> error "Type synonym was not defined"
258+ensureNoDuplicateProperties :: [(String, Value)] -> Check ()
259+ensureNoDuplicateProperties ps = guardWith "Duplicate property names" $ length (nub . map fst $ ps) == length ps
261+infer :: M.Map Ident Type -> Value -> Subst Check Type
262+infer m val = rethrow (\e -> "Error inferring type of term " ++ prettyPrintValue val ++ ":\n" ++ e) $ do
267+infer' _ (NumericLiteral _) = return Number
268+infer' _ (StringLiteral _) = return String
269+infer' _ (BooleanLiteral _) = return Boolean
270+infer' m (ArrayLiteral vals) = do
271+ ts <- mapM (infer m) vals
273+ forM_ ts $ \t -> arr ~~ Array t
275+infer' m (Unary op val) = do
278+infer' m (Binary op left right) = do
281+ inferBinary op t1 t2
282+infer' m (ObjectLiteral ps) = do
283+ lift $ ensureNoDuplicateProperties ps
284+ ts <- mapM (infer m . snd) ps
285+ let fields = zipWith (\(name, _) t -> (name, t)) ps ts
286+ return $ Object $ typesToRow fields
287+infer' m (ObjectUpdate o ps) = do
288+ lift $ ensureNoDuplicateProperties ps
291+ ts <- mapM (infer m . snd) ps
292+ let tys = zipWith (\(name, _) t -> (name, t)) ps ts
293+ obj ~~ Object (rowFromList (tys, row))
295+infer' m (Indexer index val) = do
297+ check m index Number
298+ check m val (Array el)
300+infer' m (Accessor prop val) = do
302+ propTy <- inferProperty obj prop
307+ obj `subsumes` Object (RCons prop field rest)
309+ Just ty -> return ty
310+infer' m (Abs args ret) = do
311+ ts <- replicateM (length args) fresh
312+ let m' = m `M.union` M.fromList (zip args ts)
313+ body <- infer m' ret
314+ return $ Function ts body
315+infer' m app@(App _ _) = do
316+ let (f, argss) = unfoldApplication app
319+ checkFunctionApplications m ft argss ret
321+infer' m (Var var@(Qualified mp name)) = do
324+ case M.lookup name m of
325+ Just ty -> lift $ replaceAllTypeSynonyms ty
326+ Nothing -> lookupGlobal
331+ modulePath <- checkModulePath `fmap` lift get
332+ case M.lookup (qualify modulePath var) (names env) of
333+ Nothing -> throwError $ show var ++ " is undefined"
334+ Just (ty, _) -> lift $ replaceAllTypeSynonyms ty
335+infer' m (Block ss) = do
337+ (allCodePathsReturn, _) <- checkBlock m M.empty ret ss
338+ guardWith "Block is missing a return statement" allCodePathsReturn
340+infer' m (Constructor c) = do
342+ modulePath <- checkModulePath `fmap` lift get
343+ case M.lookup (qualify modulePath c) (dataConstructors env) of
344+ Nothing -> throwError $ "Constructor " ++ show c ++ " is undefined"
345+ Just ty -> lift $ replaceAllTypeSynonyms ty
346+infer' m (Case val binders) = do
349+ checkBinders m t1 ret binders
351+infer' m (IfThenElse cond th el) = do
352+ check m cond Boolean
357+infer' m (TypedValue val ty) = do
358+ kind <- lift $ kindOf ty
359+ guardWith ("Expected type of kind *, was " ++ prettyPrintKind kind) $ kind == Star
360+ ty' <- lift $ replaceAllTypeSynonyms ty
364+inferProperty :: Type -> String -> Subst Check (Maybe Type)
365+inferProperty (Object row) prop = do
366+ let (props, _) = rowToList row
367+ return $ lookup prop props
368+inferProperty (SaturatedTypeSynonym name args) prop = do
369+ replaced <- expandTypeSynonym name args
370+ inferProperty replaced prop
371+inferProperty (ForAll ident ty) prop = do
372+ replaced <- replaceVarsWithUnknowns [ident] ty
373+ inferProperty replaced prop
374+inferProperty _ prop = return Nothing
376+inferUnary :: UnaryOperator -> Type -> Subst Check Type
378+ case fromMaybe (error "Invalid operator") $ lookup op unaryOps of
379+ (valTy, resTy) -> do
383+checkUnary :: M.Map Ident Type -> UnaryOperator -> Value -> Type -> Subst Check ()
384+checkUnary m op val res =
385+ case fromMaybe (error "Invalid operator") $ lookup op unaryOps of
386+ (valTy, resTy) -> do
390+unaryOps :: [(UnaryOperator, (Type, Type))]
391+unaryOps = [ (Negate, (Number, Number))
392+ , (Not, (Boolean, Boolean))
393+ , (BitwiseNot, (Number, Number))
396+inferBinary :: BinaryOperator -> Type -> Type -> Subst Check Type
397+inferBinary op left right | isEqualityTest op = do
400+inferBinary op left right =
401+ case fromMaybe (error "Invalid operator") $ lookup op binaryOps of
402+ (valTy, resTy) -> do
407+checkBinary :: M.Map Ident Type -> BinaryOperator -> Value -> Value -> Type -> Subst Check ()
408+checkBinary m op left right res | isEqualityTest op = do
413+checkBinary m op left right res =
414+ case fromMaybe (error "Invalid operator") $ lookup op binaryOps of
415+ (valTy, resTy) -> do
420+isEqualityTest :: BinaryOperator -> Bool
421+isEqualityTest EqualTo = True
422+isEqualityTest NotEqualTo = True
423+isEqualityTest _ = False
425+binaryOps :: [(BinaryOperator, (Type, Type))]
426+binaryOps = [ (Add, (Number, Number))
427+ , (Subtract, (Number, Number))
428+ , (Multiply, (Number, Number))
429+ , (Divide, (Number, Number))
430+ , (Modulus, (Number, Number))
431+ , (BitwiseAnd, (Number, Number))
432+ , (BitwiseOr, (Number, Number))
433+ , (BitwiseXor, (Number, Number))
434+ , (ShiftRight, (Number, Number))
435+ , (ZeroFillShiftRight, (Number, Number))
436+ , (And, (Boolean, Boolean))
437+ , (Or, (Boolean, Boolean))
438+ , (Concat, (String, String))
439+ , (Modulus, (Number, Number))
440+ , (LessThan, (Number, Boolean))
441+ , (LessThanOrEqualTo, (Number, Boolean))
442+ , (GreaterThan, (Number, Boolean))
443+ , (GreaterThanOrEqualTo, (Number, Boolean))
446+inferBinder :: Type -> Binder -> Subst Check (M.Map Ident Type)
447+inferBinder _ NullBinder = return M.empty
448+inferBinder val (StringBinder _) = val ~~ String >> return M.empty
449+inferBinder val (NumberBinder _) = val ~~ Number >> return M.empty
450+inferBinder val (BooleanBinder _) = val ~~ Boolean >> return M.empty
451+inferBinder val (VarBinder name) = return $ M.singleton name val
452+inferBinder val (NullaryBinder ctor) = do
454+ modulePath <- checkModulePath `fmap` lift get
455+ case M.lookup (qualify modulePath ctor) (dataConstructors env) of
459+ _ -> throwError $ "Constructor " ++ show ctor ++ " is not defined"
460+inferBinder val (UnaryBinder ctor binder) = do
462+ modulePath <- checkModulePath `fmap` lift get
463+ case M.lookup (qualify modulePath ctor) (dataConstructors env) of
466+ ty `subsumes` (Function [obj] val)
467+ inferBinder obj binder
468+ _ -> throwError $ "Constructor " ++ show ctor ++ " is not defined"
469+inferBinder val (ObjectBinder props) = do
472+ m1 <- inferRowProperties row rest props
476+ inferRowProperties :: Row -> Row -> [(String, Binder)] -> Subst Check (M.Map Ident Type)
477+ inferRowProperties nrow row [] = nrow ~~ row >> return M.empty
478+ inferRowProperties nrow row ((name, binder):binders) = do
480+ m1 <- inferBinder propTy binder
481+ m2 <- inferRowProperties nrow (RCons name propTy row) binders
482+ return $ m1 `M.union` m2
483+inferBinder val (ArrayBinder binders rest) = do
485+ m1 <- M.unions <$> mapM (inferBinder el) binders
488+ Nothing -> return m1
490+ m2 <- inferBinder val binder
491+ return $ m1 `M.union` m2
492+inferBinder val (NamedBinder name binder) = do
493+ m <- inferBinder val binder
494+ return $ M.insert name val m
496+inferGuardedBinder :: M.Map Ident Type -> Type -> Binder -> Subst Check (M.Map Ident Type)
497+inferGuardedBinder m val (GuardedBinder cond binder) = do
498+ m1 <- inferBinder val binder
499+ ty <- infer (m `M.union` m1) cond
502+inferGuardedBinder m val b = inferBinder val b
504+checkBinders :: M.Map Ident Type -> Type -> Type -> [(Binder, Value)] -> Subst Check ()
505+checkBinders _ _ _ [] = return ()
506+checkBinders m nval ret ((binder, val):bs) = do
507+ m1 <- inferGuardedBinder m nval binder
508+ check (m `M.union` m1) val ret
509+ checkBinders m nval ret bs
511+assignVariable :: Ident -> M.Map Ident Type -> Subst Check ()
512+assignVariable name m =
513+ case M.lookup name m of
514+ Nothing -> return ()
515+ Just _ -> throwError $ "Variable with name " ++ show name ++ " already exists."
517+checkStatement :: M.Map Ident Type -> M.Map Ident Type -> Type -> Statement -> Subst Check (Bool, M.Map Ident Type)
518+checkStatement m mass ret (VariableIntroduction name val) = do
519+ assignVariable name (m `M.union` mass)
521+ return (False, M.insert name t mass)
522+checkStatement m mass ret (Assignment ident val) = do
524+ case M.lookup ident mass of
525+ Nothing -> throwError $ "No local variable with name " ++ show ident
526+ Just ty -> do t ~~ ty
527+ return (False, mass)
528+checkStatement m mass ret (While val inner) = do
530+ (allCodePathsReturn, _) <- checkBlock m mass ret inner
531+ return (allCodePathsReturn, mass)
532+checkStatement m mass ret (If ifst) = do
533+ allCodePathsReturn <- checkIfStatement m mass ret ifst
534+ return (allCodePathsReturn, mass)
535+checkStatement m mass ret (For ident start end inner) = do
536+ assignVariable ident (m `M.union` mass)
537+ check (m `M.union` mass) start Number
538+ check (m `M.union` mass) end Number
539+ let mass1 = M.insert ident Number mass
540+ (allCodePathsReturn, _) <- checkBlock (m `M.union` mass1) mass1 ret inner
541+ return (allCodePathsReturn, mass)
542+checkStatement m mass ret (ForEach ident vals inner) = do
543+ assignVariable ident (m `M.union` mass)
545+ check (m `M.union` mass) vals (Array val)
546+ let mass1 = M.insert ident val mass
547+ (allCodePathsReturn, _) <- checkBlock (m `M.union` mass1) mass1 ret inner
548+ guardWith "Cannot return from within a foreach block" $ not allCodePathsReturn
549+ return (False, mass)
550+checkStatement m mass ret (Return val) = do
551+ check (m `M.union` mass) val ret
554+checkIfStatement :: M.Map Ident Type -> M.Map Ident Type -> Type -> IfStatement -> Subst Check Bool
555+checkIfStatement m mass ret (IfStatement val thens Nothing) = do
557+ _ <- checkBlock m mass ret thens
559+checkIfStatement m mass ret (IfStatement val thens (Just elses)) = do
561+ (allCodePathsReturn1, _) <- checkBlock m mass ret thens
562+ allCodePathsReturn2 <- checkElseStatement m mass ret elses
563+ return $ allCodePathsReturn1 && allCodePathsReturn2
565+checkElseStatement :: M.Map Ident Type -> M.Map Ident Type -> Type -> ElseStatement -> Subst Check Bool
566+checkElseStatement m mass ret (Else elses) = fst <$> checkBlock m mass ret elses
567+checkElseStatement m mass ret (ElseIf ifst) = checkIfStatement m mass ret ifst
569+checkBlock :: M.Map Ident Type -> M.Map Ident Type -> Type -> [Statement] -> Subst Check (Bool, M.Map Ident Type)
570+checkBlock _ mass _ [] = return (False, mass)
571+checkBlock m mass ret (s:ss) = do
572+ (b1, mass1) <- checkStatement (m `M.union` mass) mass ret s
574+ (True, []) -> return (True, mass1)
575+ (True, _) -> throwError "Unreachable code"
577+ (b2, mass2) <- checkBlock m mass1 ret ss
580+skolemize :: String -> Type -> Subst Check Type
581+skolemize ident ty = do
582+ tsk <- Skolem <$> fresh'
583+ rsk <- RSkolem <$> fresh'
584+ return $ replaceRowVars (M.singleton ident rsk) $ replaceTypeVars (M.singleton ident tsk) ty
586+check :: M.Map Ident Type -> Value -> Type -> Subst Check ()
587+check m val ty = rethrow errorMessage $ check' m val ty
590+ "Error checking type of term " ++
591+ prettyPrintValue val ++
593+ prettyPrintType ty ++
597+check' :: M.Map Ident Type -> Value -> Type -> Subst Check ()
598+check' m val (ForAll idents ty) = do
599+ sk <- skolemize idents ty
601+check' m val u@(TUnknown _) = do
603+ -- Don't unify an unknown with an inferred polytype
604+ ty' <- replaceAllVarsWithUnknowns ty
606+check' m (NumericLiteral _) Number = return ()
607+check' m (StringLiteral _) String = return ()
608+check' m (BooleanLiteral _) Boolean = return ()
609+check' m (Unary op val) ty = checkUnary m op val ty
610+check' m (Binary op left right) ty = checkBinary m op left right ty
611+check' m (ArrayLiteral vals) (Array ty) = forM_ vals (\val -> check m val ty)
612+check' m (Indexer index vals) ty = check m index Number >> check m vals (Array ty)
613+check' m (Abs args ret) (Function argTys retTy) = do
614+ guardWith "Incorrect number of function arguments" (length args == length argTys)
615+ let bindings = M.fromList (zip args argTys)
616+ check (bindings `M.union` m) ret retTy
617+check' m app@(App _ _) ret = do
618+ let (f, argss) = unfoldApplication app
620+ checkFunctionApplications m ft argss ret
621+check' m v@(Var var@(Qualified mp name)) ty = do
624+ case M.lookup name m of
626+ repl <- lift $ replaceAllTypeSynonyms ty1
628+ Nothing -> lookupGlobal
633+ modulePath <- checkModulePath `fmap` lift get
634+ case M.lookup (qualify modulePath var) (names env) of
635+ Nothing -> throwError $ show var ++ " is undefined"
637+ repl <- lift $ replaceAllTypeSynonyms ty1
639+check' m (TypedValue val ty1) ty2 = do
640+ kind <- lift $ kindOf ty1
641+ guardWith ("Expected type of kind *, was " ++ prettyPrintKind kind) $ kind == Star
644+check' m (Case val binders) ret = do
646+ checkBinders m t1 ret binders
647+check' m (IfThenElse cond th el) ty = do
648+ check m cond Boolean
651+check' m (ObjectLiteral ps) (Object row) = do
652+ lift $ ensureNoDuplicateProperties ps
653+ checkProperties m ps row False
654+check' m (ObjectUpdate obj ps) objTy@(Object row) = do
655+ lift $ ensureNoDuplicateProperties ps
657+ checkProperties m ps row True
658+check' m (Accessor prop val) ty = do
660+ check m val (Object (RCons prop ty rest))
661+check' m (Block ss) ret = do
662+ (allCodePathsReturn, _) <- checkBlock m M.empty ret ss
663+ guardWith "Block is missing a return statement" allCodePathsReturn
664+check' m (Constructor c) ty = do
666+ modulePath <- checkModulePath `fmap` lift get
667+ case M.lookup (qualify modulePath c) (dataConstructors env) of
668+ Nothing -> throwError $ "Constructor " ++ show c ++ " is undefined"
670+ repl <- lift $ replaceAllTypeSynonyms ty1
672+check' m val (SaturatedTypeSynonym name args) = do
673+ ty <- expandTypeSynonym name args
675+check' _ val ty = throwError $ prettyPrintValue val ++ " does not have type " ++ prettyPrintType ty
677+checkProperties :: M.Map Ident Type -> [(String, Value)] -> Row -> Bool -> Subst Check ()
678+checkProperties m ps row lax = let (ts, r') = rowToList row in go ps ts r' where
679+ go [] [] REmpty = return ()
680+ go [] [] u@(RUnknown _) = u ~~ REmpty
681+ go [] [] (RSkolem _) | lax = return ()
682+ go [] ((p, _): _) _ | lax = return ()
683+ | otherwise = throwError $ prettyPrintValue (ObjectLiteral ps) ++ " does not have property " ++ p
684+ go ((p,_):_) [] REmpty = throwError $ "Property " ++ p ++ " is not present in closed object type " ++ prettyPrintRow row
685+ go ((p,v):ps) [] u@(RUnknown _) = do
688+ u ~~ RCons p ty rest
690+ go ((p,v):ps) ts r =
695+ r ~~ RCons p ty rest
699+ go ps (delete (p, ty) ts) r
700+ go _ _ _ = throwError $ prettyPrintValue (ObjectLiteral ps) ++ " does not have type " ++ prettyPrintType (Object row)
702+unfoldApplication :: Value -> (Value, [[Value]])
703+unfoldApplication = go []
705+ go argss (App f args) = go (args:argss) f
706+ go argss f = (f, argss)
708+checkFunctionApplications :: M.Map Ident Type -> Type -> [[Value]] -> Type -> Subst Check ()
709+checkFunctionApplications _ _ [] _ = error "Nullary function application"
710+checkFunctionApplications m fnTy [args] ret = checkFunctionApplication m fnTy args ret
711+checkFunctionApplications m fnTy (args:argss) ret = do
713+ checkFunctionApplication m fnTy args f
714+ checkFunctionApplications m f argss ret
716+checkFunctionApplication :: M.Map Ident Type -> Type -> [Value] -> Type -> Subst Check ()
717+checkFunctionApplication m fnTy args ret = rethrow errorMessage $ checkFunctionApplication' m fnTy args ret
719+ errorMessage msg = "Error applying function of type "
720+ ++ prettyPrintType fnTy
721+ ++ " to arguments " ++ intercalate ", " (map prettyPrintValue args)
722+ ++ ", expecting value of type "
723+ ++ prettyPrintType ret ++ ":\n" ++ msg
725+checkFunctionApplication' :: M.Map Ident Type -> Type -> [Value] -> Type -> Subst Check ()
726+checkFunctionApplication' m (Function argTys retTy) args ret = do
727+ guardWith "Incorrect number of function arguments" (length args == length argTys)
728+ zipWithM (check m) args argTys
729+ retTy `subsumes` ret
730+checkFunctionApplication' m (ForAll ident ty) args ret = do
731+ replaced <- replaceVarsWithUnknowns [ident] ty
732+ checkFunctionApplication m replaced args ret
733+checkFunctionApplication' m u@(TUnknown _) args ret = do
734+ tyArgs <- mapM (\arg -> infer m arg >>= replaceAllVarsWithUnknowns) args
735+ u ~~ Function tyArgs ret
736+checkFunctionApplication' m (SaturatedTypeSynonym name tyArgs) args ret = do
737+ ty <- expandTypeSynonym name tyArgs
738+ checkFunctionApplication' m ty args ret
739+checkFunctionApplication' _ fnTy args ret = throwError $ "Cannot apply function of type "
740+ ++ prettyPrintType fnTy
741+ ++ " to arguments " ++ intercalate ", " (map prettyPrintValue args)
742+ ++ ". Expecting value of type " ++ prettyPrintType ret ++ "."
744+subsumes :: Type -> Type -> Subst Check ()
745+subsumes (ForAll ident ty1) ty2 = do
746+ replaced <- replaceVarsWithUnknowns [ident] ty1
747+ replaced `subsumes` ty2
748+subsumes (Function args1 ret1) (Function args2 ret2) = do
749+ zipWithM subsumes args2 args1
750+ ret1 `subsumes` ret2
751+subsumes ty1 ty2 = ty1 ~~ ty2