@@ -1,768 +0,0 @@
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, FlexibleContexts #-}
17−module Language.PureScript.TypeChecker.Types (
22−import Data.Maybe (fromMaybe)
23−import Data.Either (lefts, rights)
24−import qualified Data.Data as D
26− (mkT, something, everywhere, everywhereBut, mkQ, extQ)
28−import Language.PureScript.Values
29−import Language.PureScript.Types
30−import Language.PureScript.Kinds
31−import Language.PureScript.Names
32−import Language.PureScript.TypeChecker.Monad
33−import Language.PureScript.TypeChecker.Kinds
34−import Language.PureScript.TypeChecker.Synonyms
35−import Language.PureScript.Pretty
36−import Language.PureScript.Unknown
38−import Control.Monad.State
39−import Control.Monad.Error
40−import Control.Monad.Reader
42−import Control.Applicative
43−import Control.Arrow (Arrow(..))
45−import qualified Data.Map as M
47−instance Unifiable Type where
49− isUnknown (TUnknown u) = Just u
50− isUnknown _ = Nothing
52− apply s (TUnknown u) = runSubstitution s u
53− apply s (SaturatedTypeSynonym name tys) = SaturatedTypeSynonym name $ map (apply s) tys
54− apply s (ForAll idents ty) = ForAll idents $ apply s ty
55− apply s (Array t) = Array (apply s t)
56− apply s (Object r) = Object (apply s r)
57− apply s (Function args ret) = Function (map (apply s) args) (apply s ret)
58− apply s (TypeApp t1 t2) = TypeApp (apply s t1) (apply s t2)
60− unknowns (TUnknown (Unknown u)) = [u]
61− unknowns (SaturatedTypeSynonym _ tys) = concatMap unknowns tys
62− unknowns (ForAll _ ty) = unknowns ty
63− unknowns (Array t) = unknowns t
64− unknowns (Object r) = unknowns r
65− unknowns (Function args ret) = concatMap unknowns args ++ unknowns ret
66− unknowns (TypeApp t1 t2) = unknowns t1 ++ unknowns t2
69−instance Unifiable Row where
71− isUnknown (RUnknown u) = Just u
72− isUnknown _ = Nothing
75− (s1, r1') = rowToList r1
76− (s2, r2') = rowToList r2
77− int = [ (t1, t2) | (name, t1) <- s1, (name', t2) <- s2, name == name' ]
78− sd1 = [ (name, t1) | (name, t1) <- s1, name `notElem` map fst s2 ]
79− sd2 = [ (name, t2) | (name, t2) <- s2, name `notElem` map fst s1 ]
81− forM_ int (uncurry (~~))
82− unifyRows sd1 r1' sd2 r2'
84− unifyRows :: [(String, Type)] -> Row -> [(String, Type)] -> Row -> Subst ()
85− unifyRows [] (RUnknown u) sd r = replace u (rowFromList (sd, r))
86− unifyRows sd r [] (RUnknown u) = replace u (rowFromList (sd, r))
87− unifyRows ((name, ty):row) r others u@(RUnknown un) = do
89− forM row $ \(_, t) -> occursCheck un t
91− u ~~ RCons name ty u'
92− unifyRows row r others u'
93− unifyRows [] REmpty [] REmpty = return ()
94− unifyRows [] (RowVar v1) [] (RowVar v2) | v1 == v2 = return ()
95− unifyRows [] (RSkolem s1) [] (RSkolem s2) | s1 == s2 = return ()
96− unifyRows sd3 r3 sd4 r4 = throwError $ "Cannot unify " ++ prettyPrintRow (rowFromList (sd3, r3)) ++ " with " ++ prettyPrintRow (rowFromList (sd4, r4)) ++ "."
97− apply s (RUnknown u) = runSubstitution s u
98− apply s (RCons name ty r) = RCons name (apply s ty) (apply s r)
100− unknowns (RUnknown (Unknown u)) = [u]
101− unknowns (RCons _ ty r) = unknowns ty ++ unknowns r
104−unifyTypes :: Type -> Type -> Subst ()
105−unifyTypes t1 t2 = rethrow (\e -> "Error unifying type " ++ prettyPrintType t1 ++ " with type " ++ prettyPrintType t2 ++ ":\n" ++ e) $ do
108− unifyTypes' (TUnknown u1) (TUnknown u2) | u1 == u2 = return ()
109− unifyTypes' (TUnknown u) t = replace u t
110− unifyTypes' t (TUnknown u) = replace u t
111− unifyTypes' (SaturatedTypeSynonym name1 args1) (SaturatedTypeSynonym name2 args2)
112− | name1 == name2 = zipWithM_ unifyTypes args1 args2
113− unifyTypes' (SaturatedTypeSynonym name args) ty = do
114− ty1 <- expandTypeSynonym name args
116− unifyTypes' ty s@(SaturatedTypeSynonym _ _) = s `unifyTypes` ty
117− unifyTypes' (ForAll ident1 ty1) (ForAll ident2 ty2) = do
118− sk <- skolemize ident1 ty1
119− replaced <- replaceVarWithUnknown ident2 ty2
120− sk `unifyTypes` replaced
121− unifyTypes' (ForAll ident ty1) ty2 = do
122− sk <- skolemize ident ty1
124− unifyTypes' ty f@(ForAll _ _) = f `unifyTypes` ty
125− unifyTypes' Number Number = return ()
126− unifyTypes' String String = return ()
127− unifyTypes' Boolean Boolean = return ()
128− unifyTypes' (Array s) (Array t) = s `unifyTypes` t
129− unifyTypes' (Object row1) (Object row2) = row1 ~~ row2
130− unifyTypes' (Function args1 ret1) (Function args2 ret2) = do
131− guardWith "Function applied to incorrect number of args" $ length args1 == length args2
132− zipWithM_ unifyTypes args1 args2
133− ret1 `unifyTypes` ret2
134− unifyTypes' (TypeVar v1) (TypeVar v2) | v1 == v2 = return ()
135− unifyTypes' (TypeConstructor c1) (TypeConstructor c2) = do
136− moduleName <- substCurrentModule `fmap` ask
137− guardWith ("Cannot unify " ++ show c1 ++ " with " ++ show c2 ++ ".") (qualify moduleName c1 == qualify moduleName c2)
138− unifyTypes' (TypeApp t3 t4) (TypeApp t5 t6) = do
141− unifyTypes' (Skolem s1) (Skolem s2) | s1 == s2 = return ()
142− unifyTypes' t3 t4 = throwError $ "Cannot unify " ++ prettyPrintType t3 ++ " with " ++ prettyPrintType t4 ++ "."
144−typesOf :: ModuleName -> [(Ident, Value)] -> Check [Type]
145−typesOf moduleName vals = do
146− (tys, sub, checks) <- runSubst (SubstContext moduleName) $ do
147− let es = map isTyped vals
150− typedDict = map (\(ident, ty, _) -> (ident, ty)) typed
151− untypedNames <- replicateM (length untyped) fresh
152− let untypedDict = zip (map fst untyped) untypedNames
153− dict = M.fromList (map (\(ident, ty) -> ((moduleName, ident), (ty, LocalVariable))) $ typedDict ++ untypedDict)
154− tys <- forM es $ \e -> case e of
155− Left (_, ty, val) -> do
156− kind <- liftCheck $ kindOf moduleName ty
157− guardWith ("Expected type of kind *, was " ++ prettyPrintKind kind) $ kind == Star
158− ty' <- replaceAllTypeSynonyms ty
159− bindNames dict $ check val ty'
161− Right (ident, val) -> do
162− ty <- bindNames dict $ infer val
163− ty ~~ fromMaybe (error "name not found in dictionary") (lookup ident untypedDict)
166− forM tys $ flip (escapeCheck checks) sub
167− forM tys $ skolemEscapeCheck
168− return $ map (varIfUnknown . desaturateAllTypeSynonyms . setifyAll) tys
170−isTyped :: (Ident, Value) -> Either (Ident, Type, Value) (Ident, Value)
171−isTyped (name, TypedValue value ty) = Left (name, ty, value)
172−isTyped (name, value) = Right (name, value)
174−escapeCheck :: [AnyUnifiable] -> Type -> Substitution -> Check ()
175−escapeCheck checks ty sub =
177− visibleUnknowns = nub $ unknowns ty
179− forM_ checks $ \c -> case c of
180− AnyUnifiable t -> do
181− let unsolvedUnknowns = nub . unknowns $ apply sub t
182− guardWith "Escape check fails" $ null $ unsolvedUnknowns \\ visibleUnknowns
184−skolemEscapeCheck :: Type -> Check ()
185−skolemEscapeCheck ty =
186− case something (extQ (mkQ Nothing findSkolems) findRSkolems) ty of
187− Nothing -> return ()
188− Just _ -> throwError "Skolem variables cannot escape. Consider adding a type signature."
190− findSkolems (Skolem _) = return ()
191− findSkolems _ = mzero
192− findRSkolems (RSkolem _) = return ()
193− findRSkolems _ = mzero
196−setify = rowFromList . first (M.toList . M.fromList) . rowToList
198−setifyAll :: (D.Data d) => d -> d
199−setifyAll = everywhere (mkT setify)
201−varIfUnknown :: Type -> Type
203− let unks = nub $ unknowns ty
204− toName = (:) 't' . show
205− ty' = everywhere (mkT rowToVar) . everywhere (mkT typeToVar) $ ty
206− typeToVar :: Type -> Type
207− typeToVar (TUnknown (Unknown u)) = TypeVar (toName u)
209− rowToVar :: Row -> Row
210− rowToVar (RUnknown (Unknown u)) = RowVar (toName u)
212− in mkForAll (sort . map toName $ unks) ty'
214−replaceAllTypeVars :: (D.Data d) => [(String, Type)] -> d -> d
215−replaceAllTypeVars = foldl' (\f (name, ty) -> replaceTypeVars name ty . f) id
217−replaceTypeVars :: (D.Data d) => String -> Type -> d -> d
218−replaceTypeVars name t = everywhereBut (mkQ False isShadowed) (mkT replaceTypeVar)
220− replaceTypeVar (TypeVar v) | v == name = t
221− replaceTypeVar other = other
222− isShadowed (ForAll v _) | v == name = True
223− isShadowed _ = False
225−replaceRowVars :: (D.Data d) => String -> Row -> d -> d
226−replaceRowVars name r = everywhere (mkT replaceRowVar)
228− replaceRowVar (RowVar v) | v == name = r
229− replaceRowVar other = other
231−replaceAllVarsWithUnknowns :: Type -> Subst Type
232−replaceAllVarsWithUnknowns (ForAll ident ty) = replaceVarWithUnknown ident ty >>= replaceAllVarsWithUnknowns
233−replaceAllVarsWithUnknowns ty = return ty
235−replaceVarWithUnknown :: String -> Type -> Subst Type
236−replaceVarWithUnknown ident ty = do
239− return $ replaceRowVars ident ru . replaceTypeVars ident tu $ ty
241−replaceAllTypeSynonyms :: (Functor m, MonadState CheckState m, MonadReader SubstContext m, MonadError String m) => (D.Data d) => d -> m d
242−replaceAllTypeSynonyms d = do
244− moduleName <- substCurrentModule <$> ask
245− let syns = map (\((path, name), (args, _)) -> (Qualified (Just path) name, length args)) . M.toList $ typeSynonyms env
246− either throwError return $ saturateAllTypeSynonyms moduleName syns d
248−desaturateAllTypeSynonyms :: (D.Data d) => d -> d
249−desaturateAllTypeSynonyms = everywhere (mkT replaceSaturatedTypeSynonym)
251− replaceSaturatedTypeSynonym (SaturatedTypeSynonym name args) = foldl TypeApp (TypeConstructor name) args
252− replaceSaturatedTypeSynonym t = t
254−expandTypeSynonym :: Qualified ProperName -> [Type] -> Subst Type
255−expandTypeSynonym name args = do
257− moduleName <- substCurrentModule `fmap` ask
258− case M.lookup (qualify moduleName name) (typeSynonyms env) of
259− Just (synArgs, body) -> return $ replaceAllTypeVars (zip synArgs args) body
260− Nothing -> error "Type synonym was not defined"
262−ensureNoDuplicateProperties :: (MonadError String m) => [(String, Value)] -> m ()
263−ensureNoDuplicateProperties ps = guardWith "Duplicate property names" $ length (nub . map fst $ ps) == length ps
265−infer :: Value -> Subst Type
266−infer val = rethrow (\e -> "Error inferring type of term " ++ prettyPrintValue val ++ ":\n" ++ e) $ do
271−infer' :: Value -> Subst Type
272−infer' (NumericLiteral _) = return Number
273−infer' (StringLiteral _) = return String
274−infer' (BooleanLiteral _) = return Boolean
275−infer' (ArrayLiteral vals) = do
276− ts <- mapM (infer) vals
278− forM_ ts $ \t -> els ~~ Array t
280−infer' (Unary op val) = do
283−infer' (Binary op left right) = do
286− inferBinary op t1 t2
287−infer' (ObjectLiteral ps) = do
288− ensureNoDuplicateProperties ps
289− ts <- mapM (infer . snd) ps
290− let fields = zipWith (\(name, _) t -> (name, t)) ps ts
291− return $ Object $ rowFromList (fields, REmpty)
292−infer' (ObjectUpdate o ps) = do
293− ensureNoDuplicateProperties ps
295− newTys <- zipWith (\(name, _) t -> (name, t)) ps <$> mapM (infer . snd) ps
296− oldTys <- zip (map fst ps) <$> replicateM (length ps) fresh
297− check o $ Object $ rowFromList (oldTys, row)
298− return $ Object $ rowFromList (newTys, row)
299−infer' (Indexer index val) = do
302− check val (Array el)
304−infer' (Accessor prop val) = do
306− propTy <- inferProperty obj prop
311− obj `subsumes` Object (RCons prop field rest)
313− Just ty -> return ty
314−infer' (Abs args ret) = do
315− ts <- replicateM (length args) fresh
316− moduleName <- substCurrentModule <$> ask
317− bindLocalVariables moduleName (zip args ts) $ do
319− return $ Function ts body
320−infer' app@(App _ _) = do
321− let (f, argss) = unfoldApplication app
324− checkFunctionApplications ft argss ret
326−infer' (Var var) = do
327− moduleName <- substCurrentModule <$> ask
328− ty <- lookupVariable moduleName var
329− replaceAllTypeSynonyms ty
330−infer' (Block ss) = do
332− (allCodePathsReturn, _) <- checkBlock M.empty ret ss
333− guardWith "Block is missing a return statement" allCodePathsReturn
335−infer' (Constructor c) = do
337− moduleName <- substCurrentModule `fmap` ask
338− case M.lookup (qualify moduleName c) (dataConstructors env) of
339− Nothing -> throwError $ "Constructor " ++ show c ++ " is undefined"
340− Just ty -> replaceAllTypeSynonyms ty
341−infer' (Case vals binders) = do
342− ts <- mapM infer vals
344− checkBinders ts ret binders
346−infer' (IfThenElse cond th el) = do
352−infer' (TypedValue val ty) = do
353− moduleName <- substCurrentModule <$> ask
354− kind <- liftCheck $ kindOf moduleName ty
355− guardWith ("Expected type of kind *, was " ++ prettyPrintKind kind) $ kind == Star
356− ty' <- replaceAllTypeSynonyms ty
359−infer' _ = error "Invalid argument to infer"
361−inferProperty :: Type -> String -> Subst (Maybe Type)
362−inferProperty (Object row) prop = do
363− let (props, _) = rowToList row
364− return $ lookup prop props
365−inferProperty (SaturatedTypeSynonym name args) prop = do
366− replaced <- expandTypeSynonym name args
367− inferProperty replaced prop
368−inferProperty (ForAll ident ty) prop = do
369− replaced <- replaceVarWithUnknown ident ty
370− inferProperty replaced prop
371−inferProperty _ _ = return Nothing
373−inferUnary :: UnaryOperator -> Type -> Subst Type
375− case fromMaybe (error "Invalid operator") $ lookup op unaryOps of
376− (valTy, resTy) -> do
380−checkUnary :: UnaryOperator -> Value -> Type -> Subst ()
381−checkUnary op val res =
382− case fromMaybe (error "Invalid operator") $ lookup op unaryOps of
383− (valTy, resTy) -> do
387−unaryOps :: [(UnaryOperator, (Type, Type))]
388−unaryOps = [ (Negate, (Number, Number))
389− , (Not, (Boolean, Boolean))
390− , (BitwiseNot, (Number, Number))
393−inferBinary :: BinaryOperator -> Type -> Type -> Subst Type
394−inferBinary op left right | isEqualityTest op = do
397−inferBinary op left right =
398− case fromMaybe (error "Invalid operator") $ lookup op binaryOps of
399− (valTy, resTy) -> do
404−checkBinary :: BinaryOperator -> Value -> Value -> Type -> Subst ()
405−checkBinary op left right res | isEqualityTest op = do
410−checkBinary op left right res =
411− case fromMaybe (error "Invalid operator") $ lookup op binaryOps of
412− (valTy, resTy) -> do
417−isEqualityTest :: BinaryOperator -> Bool
418−isEqualityTest EqualTo = True
419−isEqualityTest NotEqualTo = True
420−isEqualityTest _ = False
422−binaryOps :: [(BinaryOperator, (Type, Type))]
423−binaryOps = [ (Add, (Number, Number))
424− , (Subtract, (Number, Number))
425− , (Multiply, (Number, Number))
426− , (Divide, (Number, Number))
427− , (Modulus, (Number, Number))
428− , (BitwiseAnd, (Number, Number))
429− , (BitwiseOr, (Number, Number))
430− , (BitwiseXor, (Number, Number))
431− , (ShiftRight, (Number, Number))
432− , (ZeroFillShiftRight, (Number, Number))
433− , (And, (Boolean, Boolean))
434− , (Or, (Boolean, Boolean))
435− , (Concat, (String, String))
436− , (Modulus, (Number, Number))
437− , (LessThan, (Number, Boolean))
438− , (LessThanOrEqualTo, (Number, Boolean))
439− , (GreaterThan, (Number, Boolean))
440− , (GreaterThanOrEqualTo, (Number, Boolean))
443−inferBinder :: Type -> Binder -> Subst (M.Map Ident Type)
444−inferBinder _ NullBinder = return M.empty
445−inferBinder val (StringBinder _) = val ~~ String >> return M.empty
446−inferBinder val (NumberBinder _) = val ~~ Number >> return M.empty
447−inferBinder val (BooleanBinder _) = val ~~ Boolean >> return M.empty
448−inferBinder val (VarBinder name) = return $ M.singleton name val
449−inferBinder val (NullaryBinder ctor) = do
451− moduleName <- substCurrentModule <$> ask
452− case M.lookup (qualify moduleName ctor) (dataConstructors env) of
456− _ -> throwError $ "Constructor " ++ show ctor ++ " is not defined"
457−inferBinder val (UnaryBinder ctor binder) = do
459− moduleName <- substCurrentModule <$> ask
460− case M.lookup (qualify moduleName ctor) (dataConstructors env) of
462− fn <- replaceAllVarsWithUnknowns ty
464− Function [obj] ret -> do
466− inferBinder obj binder
467− _ -> throwError $ "Constructor " ++ show ctor ++ " is not a unary constructor"
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 (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) = do
485− m1 <- M.unions <$> mapM (inferBinder el) binders
488−inferBinder val (ConsBinder headBinder tailBinder) = do
490− m1 <- inferBinder el headBinder
491− m2 <- inferBinder val tailBinder
493− return $ m1 `M.union` m2
494−inferBinder val (NamedBinder name binder) = do
495− m <- inferBinder val binder
496− return $ M.insert name val m
498−checkBinders :: [Type] -> Type -> [([Binder], Maybe Guard, Value)] -> Subst ()
499−checkBinders _ _ [] = return ()
500−checkBinders nvals ret ((binders, grd, val):bs) = do
501− moduleName <- substCurrentModule <$> ask
502− m1 <- M.unions <$> zipWithM inferBinder nvals binders
503− bindLocalVariables moduleName (M.toList m1) $ do
506− Nothing -> return ()
507− Just g -> check g Boolean
508− checkBinders nvals ret bs
510−assignVariable :: Ident -> Subst ()
511−assignVariable name = do
512− env <- checkEnv <$> get
513− moduleName <- substCurrentModule <$> ask
514− case M.lookup (moduleName, name) (names env) of
515− Just (_, LocalVariable) -> throwError $ "Variable with name " ++ show name ++ " already exists."
518−checkStatement :: M.Map Ident Type -> Type -> Statement -> Subst (Bool, M.Map Ident Type)
519−checkStatement mass _ (VariableIntroduction name val) = do
522− return (False, M.insert name t mass)
523−checkStatement mass _ (Assignment ident val) = do
525− case M.lookup ident mass of
526− Nothing -> throwError $ "No local variable with name " ++ show ident
527− Just ty -> do t ~~ ty
528− return (False, mass)
529−checkStatement mass ret (While val inner) = do
531− (allCodePathsReturn, _) <- checkBlock mass ret inner
532− return (allCodePathsReturn, mass)
533−checkStatement mass ret (If ifst) = do
534− allCodePathsReturn <- checkIfStatement mass ret ifst
535− return (allCodePathsReturn, mass)
536−checkStatement mass ret (For ident start end inner) = do
537− moduleName <- substCurrentModule <$> ask
538− assignVariable ident
541− (allCodePathsReturn, _) <- bindLocalVariables moduleName [(ident, Number)] $ checkBlock mass ret inner
542− return (allCodePathsReturn, mass)
543−checkStatement mass ret (ForEach ident vals inner) = do
544− moduleName <- substCurrentModule <$> ask
545− assignVariable ident
547− check vals (Array val)
548− (allCodePathsReturn, _) <- bindLocalVariables moduleName [(ident, val)] $ checkBlock mass ret inner
549− guardWith "Cannot return from within a foreach block" $ not allCodePathsReturn
550− return (False, mass)
551−checkStatement mass _ (ValueStatement val) = do
553− return (False, mass)
554−checkStatement mass ret (Return val) = do
558−checkIfStatement :: M.Map Ident Type -> Type -> IfStatement -> Subst Bool
559−checkIfStatement mass ret (IfStatement val thens Nothing) = do
561− _ <- checkBlock mass ret thens
563−checkIfStatement mass ret (IfStatement val thens (Just elses)) = do
565− (allCodePathsReturn1, _) <- checkBlock mass ret thens
566− allCodePathsReturn2 <- checkElseStatement mass ret elses
567− return $ allCodePathsReturn1 && allCodePathsReturn2
569−checkElseStatement :: M.Map Ident Type -> Type -> ElseStatement -> Subst Bool
570−checkElseStatement mass ret (Else elses) = fst <$> checkBlock mass ret elses
571−checkElseStatement mass ret (ElseIf ifst) = checkIfStatement mass ret ifst
573−checkBlock :: M.Map Ident Type -> Type -> [Statement] -> Subst (Bool, M.Map Ident Type)
574−checkBlock mass _ [] = return (False, mass)
575−checkBlock mass ret (s:ss) = do
576− moduleName <- substCurrentModule <$> ask
577− (b1, mass1) <- checkStatement mass ret s
578− bindLocalVariables moduleName (M.toList mass1) $ case (b1, ss) of
579− (True, []) -> return (True, mass1)
580− (True, _) -> throwError "Unreachable code"
581− (False, ss') -> checkBlock mass1 ret ss'
583−skolemize :: String -> Type -> Subst Type
584−skolemize ident ty = do
585− tsk <- Skolem <$> fresh'
586− rsk <- RSkolem <$> fresh'
587− return $ replaceRowVars ident rsk $ replaceTypeVars ident tsk ty
589−check :: Value -> Type -> Subst ()
590−check val ty = rethrow errorMessage $ check' val ty
593− "Error checking type of term " ++
594− prettyPrintValue val ++
596− prettyPrintType ty ++
600−check' :: Value -> Type -> Subst ()
601−check' val (ForAll idents ty) = do
602− sk <- skolemize idents ty
604−check' val u@(TUnknown _) = do
606− -- Don't unify an unknown with an inferred polytype
607− ty' <- replaceAllVarsWithUnknowns ty
609−check' (NumericLiteral _) Number = return ()
610−check' (StringLiteral _) String = return ()
611−check' (BooleanLiteral _) Boolean = return ()
612−check' (Unary op val) ty = checkUnary op val ty
613−check' (Binary op left right) ty = checkBinary op left right ty
614−check' (ArrayLiteral vals) (Array ty) = forM_ vals (\val -> check val ty)
615−check' (Indexer index vals) ty = check index Number >> check vals (Array ty)
616−check' (Abs args ret) (Function argTys retTy) = do
617− moduleName <- substCurrentModule <$> ask
618− guardWith "Incorrect number of function arguments" (length args == length argTys)
619− bindLocalVariables moduleName (zip args argTys) $ check ret retTy
620−check' app@(App _ _) ret = do
621− let (f, argss) = unfoldApplication app
623− checkFunctionApplications ft argss ret
624−check' (Var var) ty = do
625− moduleName <- substCurrentModule <$> ask
626− ty1 <- lookupVariable moduleName var
627− repl <- replaceAllTypeSynonyms ty1
629−check' (TypedValue val ty1) ty2 = do
630− moduleName <- substCurrentModule <$> ask
631− kind <- liftCheck $ kindOf moduleName ty1
632− guardWith ("Expected type of kind *, was " ++ prettyPrintKind kind) $ kind == Star
635−check' (Case vals binders) ret = do
636− ts <- mapM infer vals
637− checkBinders ts ret binders
638−check' (IfThenElse cond th el) ty = do
642−check' (ObjectLiteral ps) (Object row) = do
643− ensureNoDuplicateProperties ps
644− checkProperties ps row False
645−check' (ObjectUpdate obj ps) (Object row) = do
646− ensureNoDuplicateProperties ps
647− us <- zip (map fst ps) <$> replicateM (length ps) fresh
648− let (propsToCheck, rest) = rowToList row
649− propsToRemove = map fst ps
650− remainingProps = filter (\(p, _) -> p `notElem` propsToRemove) propsToCheck
651− check obj (Object (rowFromList (us ++ remainingProps, rest)))
652− checkProperties ps row True
653−check' (Accessor prop val) ty = do
655− check val (Object (RCons prop ty rest))
656−check' (Block ss) ret = do
657− (allCodePathsReturn, _) <- checkBlock M.empty ret ss
658− guardWith "Block is missing a return statement" allCodePathsReturn
659−check' (Constructor c) ty = do
661− moduleName <- substCurrentModule <$> ask
662− case M.lookup (qualify moduleName c) (dataConstructors env) of
663− Nothing -> throwError $ "Constructor " ++ show c ++ " is undefined"
665− repl <- replaceAllTypeSynonyms ty1
667−check' val (SaturatedTypeSynonym name args) = do
668− ty <- expandTypeSynonym name args
670−check' val ty = throwError $ prettyPrintValue val ++ " does not have type " ++ prettyPrintType ty
672−checkProperties :: [(String, Value)] -> Row -> Bool -> Subst ()
673−checkProperties 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−unfoldApplication :: Value -> (Value, [[Value]])
698−unfoldApplication = go []
700− go argss (App f args) = go (args:argss) f
701− go argss f = (f, argss)
703−checkFunctionApplications :: Type -> [[Value]] -> Type -> Subst ()
704−checkFunctionApplications _ [] _ = error "Nullary function application"
705−checkFunctionApplications fnTy [args] ret = checkFunctionApplication fnTy args ret
706−checkFunctionApplications fnTy (args:argss) ret = do
707− argTys <- mapM (infer) args
708− f <- inferFunctionApplication fnTy argTys
709− checkFunctionApplications f argss ret
711−checkFunctionApplication :: Type -> [Value] -> Type -> Subst ()
712−checkFunctionApplication fnTy args ret = rethrow errorMessage $ checkFunctionApplication' fnTy args ret
714− errorMessage msg = "Error applying function of type "
715− ++ prettyPrintType fnTy
716− ++ " to arguments " ++ intercalate ", " (map prettyPrintValue args)
717− ++ ", expecting value of type "
718− ++ prettyPrintType ret ++ ":\n" ++ msg
720−inferFunctionApplication :: Type -> [Type] -> Subst Type
721−inferFunctionApplication (Function argTys retTy) args = do
722− guardWith "Incorrect number of function arguments" (length args == length argTys)
723− zipWithM subsumes args argTys
725−inferFunctionApplication (ForAll ident ty) args = do
726− replaced <- replaceVarWithUnknown ident ty
727− inferFunctionApplication replaced args
728−inferFunctionApplication u@(TUnknown _) args = do
731− args' <- mapM replaceAllVarsWithUnknowns args
732− u ~~ Function args' ret
734−inferFunctionApplication (SaturatedTypeSynonym name tyArgs) args = do
735− ty <- expandTypeSynonym name tyArgs
736− inferFunctionApplication ty args
737−inferFunctionApplication fnTy args = throwError $ "Cannot apply function of type "
738− ++ prettyPrintType fnTy
739− ++ " to argument(s) of type(s) " ++ intercalate ", " (map prettyPrintType args)
741−checkFunctionApplication' :: Type -> [Value] -> Type -> Subst ()
742−checkFunctionApplication' (Function argTys retTy) args ret = do
743− guardWith "Incorrect number of function arguments" (length args == length argTys)
744− zipWithM (check) args argTys
745− retTy `subsumes` ret
746−checkFunctionApplication' (ForAll ident ty) args ret = do
747− replaced <- replaceVarWithUnknown ident ty
748− checkFunctionApplication replaced args ret
749−checkFunctionApplication' u@(TUnknown _) args ret = do
750− tyArgs <- mapM (\arg -> infer arg >>= replaceAllVarsWithUnknowns) args
751− u ~~ Function tyArgs ret
752−checkFunctionApplication' (SaturatedTypeSynonym name tyArgs) args ret = do
753− ty <- expandTypeSynonym name tyArgs
754− checkFunctionApplication' ty args ret
755−checkFunctionApplication' fnTy args ret = throwError $ "Applying a function of type "
756− ++ prettyPrintType fnTy
757− ++ " to argument(s) " ++ intercalate ", " (map prettyPrintValue args)
758− ++ " does not yield a value of type " ++ prettyPrintType ret ++ "."
760−subsumes :: Type -> Type -> Subst ()
761−subsumes (ForAll ident ty1) ty2 = do
762− replaced <- replaceVarWithUnknown ident ty1
763− replaced `subsumes` ty2
764−subsumes (Function args1 ret1) (Function args2 ret2) = do
765− zipWithM subsumes args2 args1
766− ret1 `subsumes` ret2
767−subsumes ty1 ty2 = ty1 ~~ ty2