@@ -1,766 +0,0 @@
1−-----------------------------------------------------------------------------
2−--
3−-- Module : Language.PureScript.TypeChecker.Types
4−-- Copyright : (c) Phil Freeman 2013
5−-- License : MIT
6−--
7−-- Maintainer : Phil Freeman <paf31@cantab.net>
8−-- Stability : experimental
9−-- Portability :
10−--
11−-- |
12−--
13−-----------------------------------------------------------------------------
14−
15−{-# LANGUAGE DeriveDataTypeable #-}
16−
17−module Language.PureScript.TypeChecker.Types (
18− typeOf
19−) where
20−
21−import Data.List
22−import Data.Maybe (isJust, fromMaybe)
23−import Data.Function
24−import qualified Data.Data as D
25−import Data.Generics
26− (something, everywhere, everywhereM, everything, everywhereBut,
27− mkT, mkM, mkQ, extM, extQ)
28−
29−import Language.PureScript.Values
30−import Language.PureScript.Types
31−import Language.PureScript.Kinds
32−import Language.PureScript.Names
33−import Language.PureScript.TypeChecker.Monad
34−import Language.PureScript.TypeChecker.Kinds
35−import Language.PureScript.TypeChecker.Synonyms
36−import Language.PureScript.Pretty
37−import Language.PureScript.Unknown
38−
39−import Control.Monad.State
40−import Control.Monad.Error
41−
42−import Control.Applicative
43−import Control.Arrow (Arrow(..), Kleisli(..), (***), (&&&), second)
44−import qualified Control.Category as C
45−
46−import qualified Data.Map as M
47−
48−instance Unifiable Type where
49− unknown = TUnknown
50− isUnknown (TUnknown u) = Just u
51− isUnknown _ = Nothing
52− (~~) = unifyTypes
53− apply s (TUnknown u) = runSubstitution s u
54− apply s (SaturatedTypeSynonym name tys) = SaturatedTypeSynonym name $ map (apply s) tys
55− apply s (ForAll idents ty) = ForAll idents $ apply s ty
56− apply s (Array t) = Array (apply s t)
57− apply s (Object r) = Object (apply s r)
58− apply s (Function args ret) = Function (map (apply s) args) (apply s ret)
59− apply s (TypeApp t1 t2) = TypeApp (apply s t1) (apply s t2)
60− apply _ t = t
61− unknowns (TUnknown (Unknown u)) = [u]
62− unknowns (SaturatedTypeSynonym _ tys) = concatMap unknowns tys
63− unknowns (ForAll idents ty) = unknowns ty
64− unknowns (Array t) = unknowns t
65− unknowns (Object r) = unknowns r
66− unknowns (Function args ret) = concatMap unknowns args ++ unknowns ret
67− unknowns (TypeApp t1 t2) = unknowns t1 ++ unknowns t2
68− unknowns _ = []
69−
70−instance Unifiable Row where
71− unknown = RUnknown
72− isUnknown (RUnknown u) = Just u
73− isUnknown _ = Nothing
74− r1 ~~ r2 =
75− let
76− (s1, r1') = rowToList r1
77− (s2, r2') = rowToList r2
78− int = [ (t1, t2) | (name, t1) <- s1, (name', t2) <- s2, name == name' ]
79− sd1 = [ (name, t1) | (name, t1) <- s1, name `notElem` map fst s2 ]
80− sd2 = [ (name, t2) | (name, t2) <- s2, name `notElem` map fst s1 ]
81− in do
82− forM_ int (uncurry (~~))
83− unifyRows sd1 r1' sd2 r2'
84− where
85− unifyRows :: [(String, Type)] -> Row -> [(String, Type)] -> Row -> Subst Check ()
86− unifyRows [] (RUnknown u) sd r = replace u (rowFromList (sd, r))
87− unifyRows sd r [] (RUnknown u) = replace u (rowFromList (sd, r))
88− unifyRows ns@((name, ty):row) r others u@(RUnknown un) = do
89− occursCheck un ty
90− forM row $ \(_, ty) -> occursCheck un ty
91− u' <- fresh
92− u ~~ RCons name ty u'
93− unifyRows row r others u'
94− unifyRows [] REmpty [] REmpty = return ()
95− unifyRows [] (RowVar v1) [] (RowVar v2) | v1 == v2 = return ()
96− unifyRows [] (RSkolem s1) [] (RSkolem s2) | s1 == s2 = return ()
97− unifyRows sd1 r1 sd2 r2 = throwError $ "Cannot unify " ++ prettyPrintRow (rowFromList (sd1, r1)) ++ " with " ++ prettyPrintRow (rowFromList (sd2, r2)) ++ "."
98− apply s (RUnknown u) = runSubstitution s u
99− apply s (RCons name ty r) = RCons name (apply s ty) (apply s r)
100− apply _ r = r
101− unknowns (RUnknown (Unknown u)) = [u]
102− unknowns (RCons _ ty r) = unknowns ty ++ unknowns r
103− unknowns _ = []
104−
105−unifyTypes :: Type -> Type -> Subst Check ()
106−unifyTypes t1 t2 = rethrow (\e -> "Error unifying type " ++ prettyPrintType t1 ++ " with type " ++ prettyPrintType t2 ++ ":\n" ++ e) $ do
107− unifyTypes' t1 t2
108− where
109− unifyTypes' (TUnknown u1) (TUnknown u2) | u1 == u2 = return ()
110− unifyTypes' (TUnknown u) t = replace u t
111− unifyTypes' t (TUnknown u) = replace u t
112− unifyTypes' (SaturatedTypeSynonym name1 args1) (SaturatedTypeSynonym name2 args2)
113− | name1 == name2 = zipWithM_ unifyTypes args1 args2
114− unifyTypes' (SaturatedTypeSynonym name args) ty = do
115− ty1 <- expandTypeSynonym name args
116− ty1 `unifyTypes` ty
117− unifyTypes' ty s@(SaturatedTypeSynonym _ _) = s `unifyTypes` ty
118− unifyTypes' (ForAll ident1 ty1) (ForAll ident2 ty2) = do
119− sk <- skolemize ident1 ty1
120− replaced <- replaceVarsWithUnknowns [ident2] ty2
121− sk `unifyTypes` replaced
122− unifyTypes' (ForAll ident ty1) ty2 = do
123− sk <- skolemize ident ty1
124− sk `unifyTypes` ty2
125− unifyTypes' ty f@(ForAll _ _) = f `unifyTypes` ty
126− unifyTypes' Number Number = return ()
127− unifyTypes' String String = return ()
128− unifyTypes' Boolean Boolean = return ()
129− unifyTypes' (Array s) (Array t) = s `unifyTypes` t
130− unifyTypes' (Object row1) (Object row2) = row1 ~~ row2
131− unifyTypes' (Function args1 ret1) (Function args2 ret2) = do
132− guardWith "Function applied to incorrect number of args" $ length args1 == length args2
133− zipWithM_ unifyTypes args1 args2
134− ret1 `unifyTypes` ret2
135− unifyTypes' (TypeVar v1) (TypeVar v2) | v1 == v2 = return ()
136− unifyTypes' (TypeConstructor c1) (TypeConstructor c2) = do
137− modulePath <- checkModulePath `fmap` lift get
138− guardWith ("Cannot unify " ++ show c1 ++ " with " ++ show c2 ++ ".") (qualify modulePath c1 == qualify modulePath c2)
139− unifyTypes' (TypeApp t1 t2) (TypeApp t3 t4) = do
140− t1 `unifyTypes` t3
141− t2 `unifyTypes` t4
142− unifyTypes' (Skolem s1) (Skolem s2) | s1 == s2 = return ()
143− unifyTypes' t1 t2 = throwError $ "Cannot unify " ++ prettyPrintType t1 ++ " with " ++ prettyPrintType t2 ++ "."
144−
145−isFunction :: Value -> Bool
146−isFunction (Abs _ _) = True
147−isFunction (TypedValue untyped _) = isFunction untyped
148−isFunction _ = False
149−
150−typeOf :: Maybe Ident -> Value -> Check Type
151−typeOf name val = do
152− (ty, sub, checks) <- runSubst $ case name of
153− Just ident | isFunction val ->
154− case val of
155− TypedValue val ty -> do
156− kind <- lift $ kindOf ty
157− guardWith ("Expected type of kind *, was " ++ prettyPrintKind kind) $ kind == Star
158− ty' <- lift $ replaceAllTypeSynonyms ty
159− check (M.singleton ident ty) val ty'
160− return ty'
161− _ -> do
162− me <- fresh
163− ty <- infer (M.singleton ident me) val
164− ty ~~ me
165− return ty
166− _ -> infer M.empty val
167− escapeCheck checks ty sub
168− skolemEscapeCheck ty
169− return $ varIfUnknown $ desaturateAllTypeSynonyms $ setifyAll ty
170−
171−escapeCheck :: [AnyUnifiable] -> Type -> Substitution -> Check ()
172−escapeCheck checks ty sub =
173− let
174− visibleUnknowns = nub $ unknowns ty
175− in
176− forM_ checks $ \check -> case check of
177− AnyUnifiable t -> do
178− let unsolvedUnknowns = nub . unknowns $ apply sub t
179− guardWith "Escape check fails" $ null $ unsolvedUnknowns \\ visibleUnknowns
180−
181−skolemEscapeCheck :: Type -> Check ()
182−skolemEscapeCheck ty =
183− case something (extQ (mkQ Nothing findSkolems) findRSkolems) ty of
184− Nothing -> return ()
185− Just _ -> throwError "Skolem variables cannot escape. Consider adding a type signature."
186− where
187− findSkolems (Skolem _) = return ()
188− findSkolems _ = mzero
189− findRSkolems (RSkolem _) = return ()
190− findRSkolems _ = mzero
191−
192−setify :: Row -> Row
193−setify = rowFromList . first (M.toList . M.fromList) . rowToList
194−
195−setifyAll :: (D.Data d) => d -> d
196−setifyAll = everywhere (mkT setify)
197−
198−varIfUnknown :: Type -> Type
199−varIfUnknown ty = mkForAll (sort . map ((:) 'u' . show) . nub $ unknowns ty) ty
200−
201−replaceAllTypeVars :: (D.Data d) => [(String, Type)] -> d -> d
202−replaceAllTypeVars = foldl' (\f (name, ty) -> replaceTypeVars name ty . f) id
203−
204−replaceTypeVars :: (D.Data d) => String -> Type -> d -> d
205−replaceTypeVars name t = everywhereBut (mkQ False isShadowed) (mkT replace)
206− where
207− replace (TypeVar v) | v == name = t
208− replace t = t
209− isShadowed (ForAll v _) | v == name = True
210− isShadowed _ = False
211−
212−replaceRowVars :: (D.Data d) => String -> Row -> d -> d
213−replaceRowVars name r = everywhere (mkT replace)
214− where
215− replace (RowVar v) | v == name = r
216− replace t = t
217−
218−replaceAllVarsWithUnknowns :: Type -> Subst Check Type
219−replaceAllVarsWithUnknowns (ForAll ident ty) = replaceVarsWithUnknowns [ident] ty >>= replaceAllVarsWithUnknowns
220−replaceAllVarsWithUnknowns ty = return ty
221−
222−replaceVarsWithUnknowns :: [String] -> Type -> Subst Check Type
223−replaceVarsWithUnknowns idents = flip evalStateT M.empty . everywhereM (flip extM f $ mkM g)
224− where
225− f :: Type -> StateT (M.Map String Int) (Subst Check) Type
226− f (TypeVar var) | var `elem` idents = do
227− m <- get
228− n <- lift fresh'
229− case M.lookup var m of
230− Nothing -> do
231− put (M.insert var n m)
232− return $ TUnknown (Unknown n)
233− Just u -> return $ TUnknown (Unknown u)
234− f t = return t
235− g :: Row -> StateT (M.Map String Int) (Subst Check) Row
236− g (RowVar var) | var `elem` idents = do
237− m <- get
238− n <- lift fresh'
239− case M.lookup var m of
240− Nothing -> do
241− put (M.insert var n m)
242− return $ RUnknown (Unknown n)
243− Just u -> return $ RUnknown (Unknown u)
244− g r = return r
245−
246−replaceAllTypeSynonyms :: (D.Data d) => d -> Check d
247−replaceAllTypeSynonyms d = do
248− env <- getEnv
249− let syns = map (\((path, name), (args, _)) -> (Qualified path name, length args)) . M.toList $ typeSynonyms env
250− either throwError return $ saturateAllTypeSynonyms syns d
251−
252−desaturateAllTypeSynonyms :: (D.Data d) => d -> d
253−desaturateAllTypeSynonyms = everywhere (mkT replace)
254− where
255− replace (SaturatedTypeSynonym name args) = foldl TypeApp (TypeConstructor name) args
256− replace t = t
257−
258−expandAllTypeSynonyms :: Type -> Subst Check Type
259−expandAllTypeSynonyms (SaturatedTypeSynonym name args) = expandTypeSynonym name args >>= expandAllTypeSynonyms
260−expandAllTypeSynonyms ty = return ty
261−
262−expandTypeSynonym :: Qualified ProperName -> [Type] -> Subst Check Type
263−expandTypeSynonym name args = do
264− env <- lift getEnv
265− modulePath <- checkModulePath `fmap` lift get
266− case M.lookup (qualify modulePath name) (typeSynonyms env) of
267− Just (synArgs, body) -> return $ replaceAllTypeVars (zip synArgs args) body
268− Nothing -> error "Type synonym was not defined"
269−
270−ensureNoDuplicateProperties :: [(String, Value)] -> Check ()
271−ensureNoDuplicateProperties ps = guardWith "Duplicate property names" $ length (nub . map fst $ ps) == length ps
272−
273−infer :: M.Map Ident Type -> Value -> Subst Check Type
274−infer m val = rethrow (\e -> "Error inferring type of term " ++ prettyPrintValue val ++ ":\n" ++ e) $ do
275− ty <- infer' m val
276− escapeCheckLater ty
277− return ty
278−
279−infer' _ (NumericLiteral _) = return Number
280−infer' _ (StringLiteral _) = return String
281−infer' _ (BooleanLiteral _) = return Boolean
282−infer' m (ArrayLiteral vals) = do
283− ts <- mapM (infer m) vals
284− arr <- fresh
285− forM_ ts $ \t -> arr ~~ Array t
286− return arr
287−infer' m (Unary op val) = do
288− t <- infer m val
289− inferUnary op t
290−infer' m (Binary op left right) = do
291− t1 <- infer m left
292− t2 <- infer m right
293− inferBinary op t1 t2
294−infer' m (ObjectLiteral ps) = do
295− lift $ ensureNoDuplicateProperties ps
296− ts <- mapM (infer m . snd) ps
297− let fields = zipWith (\(name, _) t -> (name, t)) ps ts
298− return $ Object $ rowFromList (fields, REmpty)
299−infer' m (ObjectUpdate o ps) = do
300− lift $ ensureNoDuplicateProperties ps
301− row <- fresh
302− newTys <- zipWith (\(name, _) t -> (name, t)) ps <$> mapM (infer m . snd) ps
303− oldTys <- zip (map fst ps) <$> replicateM (length ps) fresh
304− check m o $ Object $ rowFromList (oldTys, row)
305− return $ Object $ rowFromList (newTys, row)
306−infer' m (Indexer index val) = do
307− el <- fresh
308− check m index Number
309− check m val (Array el)
310− return el
311−infer' m (Accessor prop val) = do
312− obj <- infer m val
313− propTy <- inferProperty obj prop
314− case propTy of
315− Nothing -> do
316− field <- fresh
317− rest <- fresh
318− obj `subsumes` Object (RCons prop field rest)
319− return field
320− Just ty -> return ty
321−infer' m (Abs args ret) = do
322− ts <- replicateM (length args) fresh
323− let m' = m `M.union` M.fromList (zip args ts)
324− body <- infer m' ret
325− return $ Function ts body
326−infer' m app@(App _ _) = do
327− let (f, argss) = unfoldApplication app
328− ft <- infer m f
329− ret <- fresh
330− checkFunctionApplications m ft argss ret
331− return ret
332−infer' m (Var var@(Qualified mp name)) = do
333− case mp of
334− ModulePath [] ->
335− case M.lookup name m of
336− Just ty -> lift $ replaceAllTypeSynonyms ty
337− Nothing -> lookupGlobal
338− _ -> lookupGlobal
339− where
340− lookupGlobal = do
341− env <- lift getEnv
342− modulePath <- checkModulePath `fmap` lift get
343− case M.lookup (qualify modulePath var) (names env) of
344− Nothing -> throwError $ show var ++ " is undefined"
345− Just (ty, _) -> lift $ replaceAllTypeSynonyms ty
346−infer' m (Block ss) = do
347− ret <- fresh
348− (allCodePathsReturn, _) <- checkBlock m M.empty ret ss
349− guardWith "Block is missing a return statement" allCodePathsReturn
350− return ret
351−infer' m (Constructor c) = do
352− env <- lift getEnv
353− modulePath <- checkModulePath `fmap` lift get
354− case M.lookup (qualify modulePath c) (dataConstructors env) of
355− Nothing -> throwError $ "Constructor " ++ show c ++ " is undefined"
356− Just ty -> lift $ replaceAllTypeSynonyms ty
357−infer' m (Case val binders) = do
358− t1 <- infer m val
359− ret <- fresh
360− checkBinders m t1 ret binders
361− return ret
362−infer' m (IfThenElse cond th el) = do
363− check m cond Boolean
364− t2 <- infer m th
365− t3 <- infer m el
366− t2 ~~ t3
367− return t2
368−infer' m (TypedValue val ty) = do
369− kind <- lift $ kindOf ty
370− guardWith ("Expected type of kind *, was " ++ prettyPrintKind kind) $ kind == Star
371− ty' <- lift $ replaceAllTypeSynonyms ty
372− check m val ty'
373− return ty'
374−
375−inferProperty :: Type -> String -> Subst Check (Maybe Type)
376−inferProperty (Object row) prop = do
377− let (props, _) = rowToList row
378− return $ lookup prop props
379−inferProperty (SaturatedTypeSynonym name args) prop = do
380− replaced <- expandTypeSynonym name args
381− inferProperty replaced prop
382−inferProperty (ForAll ident ty) prop = do
383− replaced <- replaceVarsWithUnknowns [ident] ty
384− inferProperty replaced prop
385−inferProperty _ prop = return Nothing
386−
387−inferUnary :: UnaryOperator -> Type -> Subst Check Type
388−inferUnary op val =
389− case fromMaybe (error "Invalid operator") $ lookup op unaryOps of
390− (valTy, resTy) -> do
391− val ~~ valTy
392− return resTy
393−
394−checkUnary :: M.Map Ident Type -> UnaryOperator -> Value -> Type -> Subst Check ()
395−checkUnary m op val res =
396− case fromMaybe (error "Invalid operator") $ lookup op unaryOps of
397− (valTy, resTy) -> do
398− res ~~ resTy
399− check m val valTy
400−
401−unaryOps :: [(UnaryOperator, (Type, Type))]
402−unaryOps = [ (Negate, (Number, Number))
403− , (Not, (Boolean, Boolean))
404− , (BitwiseNot, (Number, Number))
405− ]
406−
407−inferBinary :: BinaryOperator -> Type -> Type -> Subst Check Type
408−inferBinary op left right | isEqualityTest op = do
409− left ~~ right
410− return Boolean
411−inferBinary op left right =
412− case fromMaybe (error "Invalid operator") $ lookup op binaryOps of
413− (valTy, resTy) -> do
414− left ~~ valTy
415− right ~~ valTy
416− return resTy
417−
418−checkBinary :: M.Map Ident Type -> BinaryOperator -> Value -> Value -> Type -> Subst Check ()
419−checkBinary m op left right res | isEqualityTest op = do
420− res ~~ Boolean
421− t1 <- infer m left
422− t2 <- infer m right
423− t1 ~~ t2
424−checkBinary m op left right res =
425− case fromMaybe (error "Invalid operator") $ lookup op binaryOps of
426− (valTy, resTy) -> do
427− res ~~ resTy
428− check m left valTy
429− check m right valTy
430−
431−isEqualityTest :: BinaryOperator -> Bool
432−isEqualityTest EqualTo = True
433−isEqualityTest NotEqualTo = True
434−isEqualityTest _ = False
435−
436−binaryOps :: [(BinaryOperator, (Type, Type))]
437−binaryOps = [ (Add, (Number, Number))
438− , (Subtract, (Number, Number))
439− , (Multiply, (Number, Number))
440− , (Divide, (Number, Number))
441− , (Modulus, (Number, Number))
442− , (BitwiseAnd, (Number, Number))
443− , (BitwiseOr, (Number, Number))
444− , (BitwiseXor, (Number, Number))
445− , (ShiftRight, (Number, Number))
446− , (ZeroFillShiftRight, (Number, Number))
447− , (And, (Boolean, Boolean))
448− , (Or, (Boolean, Boolean))
449− , (Concat, (String, String))
450− , (Modulus, (Number, Number))
451− , (LessThan, (Number, Boolean))
452− , (LessThanOrEqualTo, (Number, Boolean))
453− , (GreaterThan, (Number, Boolean))
454− , (GreaterThanOrEqualTo, (Number, Boolean))
455− ]
456−
457−inferBinder :: Type -> Binder -> Subst Check (M.Map Ident Type)
458−inferBinder _ NullBinder = return M.empty
459−inferBinder val (StringBinder _) = val ~~ String >> return M.empty
460−inferBinder val (NumberBinder _) = val ~~ Number >> return M.empty
461−inferBinder val (BooleanBinder _) = val ~~ Boolean >> return M.empty
462−inferBinder val (VarBinder name) = return $ M.singleton name val
463−inferBinder val (NullaryBinder ctor) = do
464− env <- lift getEnv
465− modulePath <- checkModulePath `fmap` lift get
466− case M.lookup (qualify modulePath ctor) (dataConstructors env) of
467− Just ty -> do
468− ty `subsumes` val
469− return M.empty
470− _ -> throwError $ "Constructor " ++ show ctor ++ " is not defined"
471−inferBinder val (UnaryBinder ctor binder) = do
472− env <- lift getEnv
473− modulePath <- checkModulePath `fmap` lift get
474− case M.lookup (qualify modulePath ctor) (dataConstructors env) of
475− Just ty -> do
476− Function [obj] ret <- replaceAllVarsWithUnknowns ty
477− val `subsumes` ret
478− inferBinder obj binder
479− _ -> throwError $ "Constructor " ++ show ctor ++ " is not defined"
480−inferBinder val (ObjectBinder props) = do
481− row <- fresh
482− rest <- fresh
483− m1 <- inferRowProperties row rest props
484− val ~~ Object row
485− return m1
486− where
487− inferRowProperties :: Row -> Row -> [(String, Binder)] -> Subst Check (M.Map Ident Type)
488− inferRowProperties nrow row [] = nrow ~~ row >> return M.empty
489− inferRowProperties nrow row ((name, binder):binders) = do
490− propTy <- fresh
491− m1 <- inferBinder propTy binder
492− m2 <- inferRowProperties nrow (RCons name propTy row) binders
493− return $ m1 `M.union` m2
494−inferBinder val (ArrayBinder binders rest) = do
495− el <- fresh
496− m1 <- M.unions <$> mapM (inferBinder el) binders
497− val ~~ Array el
498− case rest of
499− Nothing -> return m1
500− Just binder -> do
501− m2 <- inferBinder val binder
502− return $ m1 `M.union` m2
503−inferBinder val (NamedBinder name binder) = do
504− m <- inferBinder val binder
505− return $ M.insert name val m
506−
507−inferGuardedBinder :: M.Map Ident Type -> Type -> Binder -> Subst Check (M.Map Ident Type)
508−inferGuardedBinder m val (GuardedBinder cond binder) = do
509− m1 <- inferBinder val binder
510− check (m1 `M.union` m) cond Boolean
511− return m1
512−inferGuardedBinder m val b = inferBinder val b
513−
514−checkBinders :: M.Map Ident Type -> Type -> Type -> [(Binder, Value)] -> Subst Check ()
515−checkBinders _ _ _ [] = return ()
516−checkBinders m nval ret ((binder, val):bs) = do
517− m1 <- inferGuardedBinder m nval binder
518− check (m1 `M.union` m) val ret
519− checkBinders m nval ret bs
520−
521−assignVariable :: Ident -> M.Map Ident Type -> Subst Check ()
522−assignVariable name m =
523− case M.lookup name m of
524− Nothing -> return ()
525− Just _ -> throwError $ "Variable with name " ++ show name ++ " already exists."
526−
527−checkStatement :: M.Map Ident Type -> M.Map Ident Type -> Type -> Statement -> Subst Check (Bool, M.Map Ident Type)
528−checkStatement m mass ret (VariableIntroduction name val) = do
529− assignVariable name (m `M.union` mass)
530− t <- infer m val
531− return (False, M.insert name t mass)
532−checkStatement m mass ret (Assignment ident val) = do
533− t <- infer m val
534− case M.lookup ident mass of
535− Nothing -> throwError $ "No local variable with name " ++ show ident
536− Just ty -> do t ~~ ty
537− return (False, mass)
538−checkStatement m mass ret (While val inner) = do
539− check m val Boolean
540− (allCodePathsReturn, _) <- checkBlock m mass ret inner
541− return (allCodePathsReturn, mass)
542−checkStatement m mass ret (If ifst) = do
543− allCodePathsReturn <- checkIfStatement m mass ret ifst
544− return (allCodePathsReturn, mass)
545−checkStatement m mass ret (For ident start end inner) = do
546− assignVariable ident (m `M.union` mass)
547− check (m `M.union` mass) start Number
548− check (m `M.union` mass) end Number
549− let mass1 = M.insert ident Number mass
550− (allCodePathsReturn, _) <- checkBlock (m `M.union` mass1) mass1 ret inner
551− return (allCodePathsReturn, mass)
552−checkStatement m mass ret (ForEach ident vals inner) = do
553− assignVariable ident (m `M.union` mass)
554− val <- fresh
555− check (m `M.union` mass) vals (Array val)
556− let mass1 = M.insert ident val mass
557− (allCodePathsReturn, _) <- checkBlock (m `M.union` mass1) mass1 ret inner
558− guardWith "Cannot return from within a foreach block" $ not allCodePathsReturn
559− return (False, mass)
560−checkStatement m mass ret (Return val) = do
561− check (m `M.union` mass) val ret
562− return (True, mass)
563−
564−checkIfStatement :: M.Map Ident Type -> M.Map Ident Type -> Type -> IfStatement -> Subst Check Bool
565−checkIfStatement m mass ret (IfStatement val thens Nothing) = do
566− check m val Boolean
567− _ <- checkBlock m mass ret thens
568− return False
569−checkIfStatement m mass ret (IfStatement val thens (Just elses)) = do
570− check m val Boolean
571− (allCodePathsReturn1, _) <- checkBlock m mass ret thens
572− allCodePathsReturn2 <- checkElseStatement m mass ret elses
573− return $ allCodePathsReturn1 && allCodePathsReturn2
574−
575−checkElseStatement :: M.Map Ident Type -> M.Map Ident Type -> Type -> ElseStatement -> Subst Check Bool
576−checkElseStatement m mass ret (Else elses) = fst <$> checkBlock m mass ret elses
577−checkElseStatement m mass ret (ElseIf ifst) = checkIfStatement m mass ret ifst
578−
579−checkBlock :: M.Map Ident Type -> M.Map Ident Type -> Type -> [Statement] -> Subst Check (Bool, M.Map Ident Type)
580−checkBlock _ mass _ [] = return (False, mass)
581−checkBlock m mass ret (s:ss) = do
582− (b1, mass1) <- checkStatement (m `M.union` mass) mass ret s
583− case (b1, ss) of
584− (True, []) -> return (True, mass1)
585− (True, _) -> throwError "Unreachable code"
586− (False, ss) -> do
587− (b2, mass2) <- checkBlock m mass1 ret ss
588− return (b2, mass2)
589−
590−skolemize :: String -> Type -> Subst Check Type
591−skolemize ident ty = do
592− tsk <- Skolem <$> fresh'
593− rsk <- RSkolem <$> fresh'
594− return $ replaceRowVars ident rsk $ replaceTypeVars ident tsk ty
595−
596−check :: M.Map Ident Type -> Value -> Type -> Subst Check ()
597−check m val ty = rethrow errorMessage $ check' m val ty
598− where
599− errorMessage msg =
600− "Error checking type of term " ++
601− prettyPrintValue val ++
602− " against type " ++
603− prettyPrintType ty ++
604− ":\n" ++
605− msg
606−
607−check' :: M.Map Ident Type -> Value -> Type -> Subst Check ()
608−check' m val (ForAll idents ty) = do
609− sk <- skolemize idents ty
610− check m val sk
611−check' m val u@(TUnknown _) = do
612− ty <- infer m val
613− -- Don't unify an unknown with an inferred polytype
614− ty' <- replaceAllVarsWithUnknowns ty
615− ty' ~~ u
616−check' m (NumericLiteral _) Number = return ()
617−check' m (StringLiteral _) String = return ()
618−check' m (BooleanLiteral _) Boolean = return ()
619−check' m (Unary op val) ty = checkUnary m op val ty
620−check' m (Binary op left right) ty = checkBinary m op left right ty
621−check' m (ArrayLiteral vals) (Array ty) = forM_ vals (\val -> check m val ty)
622−check' m (Indexer index vals) ty = check m index Number >> check m vals (Array ty)
623−check' m (Abs args ret) (Function argTys retTy) = do
624− guardWith "Incorrect number of function arguments" (length args == length argTys)
625− let bindings = M.fromList (zip args argTys)
626− check (bindings `M.union` m) ret retTy
627−check' m app@(App _ _) ret = do
628− let (f, argss) = unfoldApplication app
629− ft <- infer m f
630− checkFunctionApplications m ft argss ret
631−check' m v@(Var var@(Qualified mp name)) ty = do
632− case mp of
633− ModulePath [] ->
634− case M.lookup name m of
635− Just ty1 -> do
636− repl <- lift $ replaceAllTypeSynonyms ty1
637− repl `subsumes` ty
638− Nothing -> lookupGlobal
639− _ -> lookupGlobal
640− where
641− lookupGlobal = do
642− env <- lift getEnv
643− modulePath <- checkModulePath `fmap` lift get
644− case M.lookup (qualify modulePath var) (names env) of
645− Nothing -> throwError $ show var ++ " is undefined"
646− Just (ty1, _) -> do
647− repl <- lift $ replaceAllTypeSynonyms ty1
648− repl `subsumes` ty
649−check' m (TypedValue val ty1) ty2 = do
650− kind <- lift $ kindOf ty1
651− guardWith ("Expected type of kind *, was " ++ prettyPrintKind kind) $ kind == Star
652− ty1 `subsumes` ty2
653− check m val ty1
654−check' m (Case val binders) ret = do
655− t1 <- infer m val
656− checkBinders m t1 ret binders
657−check' m (IfThenElse cond th el) ty = do
658− check m cond Boolean
659− check m th ty
660− check m el ty
661−check' m (ObjectLiteral ps) (Object row) = do
662− lift $ ensureNoDuplicateProperties ps
663− checkProperties m ps row False
664−check' m (ObjectUpdate obj ps) (Object row) = do
665− lift $ ensureNoDuplicateProperties ps
666− us <- zip (map fst ps) <$> replicateM (length ps) fresh
667− let (propsToCheck, rest) = rowToList row
668− propsToRemove = map fst ps
669− remainingProps = filter (\(p, _) -> p `notElem` propsToRemove) propsToCheck
670− check m obj (Object (rowFromList (us ++ remainingProps, rest)))
671− checkProperties m ps row True
672−check' m (Accessor prop val) ty = do
673− rest <- fresh
674− check m val (Object (RCons prop ty rest))
675−check' m (Block ss) ret = do
676− (allCodePathsReturn, _) <- checkBlock m M.empty ret ss
677− guardWith "Block is missing a return statement" allCodePathsReturn
678−check' m (Constructor c) ty = do
679− env <- lift getEnv
680− modulePath <- checkModulePath `fmap` lift get
681− case M.lookup (qualify modulePath c) (dataConstructors env) of
682− Nothing -> throwError $ "Constructor " ++ show c ++ " is undefined"
683− Just ty1 -> do
684− repl <- lift $ replaceAllTypeSynonyms ty1
685− repl `subsumes` ty
686−check' m val (SaturatedTypeSynonym name args) = do
687− ty <- expandTypeSynonym name args
688− check m val ty
689−check' _ val ty = throwError $ prettyPrintValue val ++ " does not have type " ++ prettyPrintType ty
690−
691−checkProperties :: M.Map Ident Type -> [(String, Value)] -> Row -> Bool -> Subst Check ()
692−checkProperties m ps row lax = let (ts, r') = rowToList row in go ps ts r' where
693− go [] [] REmpty = return ()
694− go [] [] u@(RUnknown _) = u ~~ REmpty
695− go [] [] (RSkolem _) | lax = return ()
696− go [] ((p, _): _) _ | lax = return ()
697− | otherwise = throwError $ prettyPrintValue (ObjectLiteral ps) ++ " does not have property " ++ p
698− go ((p,_):_) [] REmpty = throwError $ "Property " ++ p ++ " is not present in closed object type " ++ prettyPrintRow row
699− go ((p,v):ps) [] u@(RUnknown _) = do
700− ty <- infer m v
701− rest <- fresh
702− u ~~ RCons p ty rest
703− go ps [] rest
704− go ((p,v):ps) ts r =
705− case lookup p ts of
706− Nothing -> do
707− ty <- infer m v
708− rest <- fresh
709− r ~~ RCons p ty rest
710− go ps ts rest
711− Just ty -> do
712− check m v ty
713− go ps (delete (p, ty) ts) r
714− go _ _ _ = throwError $ prettyPrintValue (ObjectLiteral ps) ++ " does not have type " ++ prettyPrintType (Object row)
715−
716−unfoldApplication :: Value -> (Value, [[Value]])
717−unfoldApplication = go []
718− where
719− go argss (App f args) = go (args:argss) f
720− go argss f = (f, argss)
721−
722−checkFunctionApplications :: M.Map Ident Type -> Type -> [[Value]] -> Type -> Subst Check ()
723−checkFunctionApplications _ _ [] _ = error "Nullary function application"
724−checkFunctionApplications m fnTy [args] ret = checkFunctionApplication m fnTy args ret
725−checkFunctionApplications m fnTy (args:argss) ret = do
726− f <- fresh
727− checkFunctionApplication m fnTy args f
728− checkFunctionApplications m f argss ret
729−
730−checkFunctionApplication :: M.Map Ident Type -> Type -> [Value] -> Type -> Subst Check ()
731−checkFunctionApplication m fnTy args ret = rethrow errorMessage $ checkFunctionApplication' m fnTy args ret
732− where
733− errorMessage msg = "Error applying function of type "
734− ++ prettyPrintType fnTy
735− ++ " to arguments " ++ intercalate ", " (map prettyPrintValue args)
736− ++ ", expecting value of type "
737− ++ prettyPrintType ret ++ ":\n" ++ msg
738−
739−checkFunctionApplication' :: M.Map Ident Type -> Type -> [Value] -> Type -> Subst Check ()
740−checkFunctionApplication' m (Function argTys retTy) args ret = do
741− guardWith "Incorrect number of function arguments" (length args == length argTys)
742− zipWithM (check m) args argTys
743− retTy `subsumes` ret
744−checkFunctionApplication' m (ForAll ident ty) args ret = do
745− replaced <- replaceVarsWithUnknowns [ident] ty
746− checkFunctionApplication m replaced args ret
747−checkFunctionApplication' m u@(TUnknown _) args ret = do
748− tyArgs <- mapM (\arg -> infer m arg >>= replaceAllVarsWithUnknowns) args
749− u ~~ Function tyArgs ret
750−checkFunctionApplication' m (SaturatedTypeSynonym name tyArgs) args ret = do
751− ty <- expandTypeSynonym name tyArgs
752− checkFunctionApplication' m ty args ret
753−checkFunctionApplication' _ fnTy args ret = throwError $ "Cannot apply function of type "
754− ++ prettyPrintType fnTy
755− ++ " to arguments " ++ intercalate ", " (map prettyPrintValue args)
756− ++ ". Expecting value of type " ++ prettyPrintType ret ++ "."
757−
758−subsumes :: Type -> Type -> Subst Check ()
759−subsumes (ForAll ident ty1) ty2 = do
760− replaced <- replaceVarsWithUnknowns [ident] ty1
761− replaced `subsumes` ty2
762−subsumes (Function args1 ret1) (Function args2 ret2) = do
763− zipWithM subsumes args2 args1
764− ret1 `subsumes` ret2
765−subsumes ty1 ty2 = ty1 ~~ ty2
766−