@@ -1,748 +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 <- replaceVarWithUnknown 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) = replaceVarWithUnknown ident ty >>= replaceAllVarsWithUnknowns
220−replaceAllVarsWithUnknowns ty = return ty
221−
222−replaceVarWithUnknown :: String -> Type -> Subst Check Type
223−replaceVarWithUnknown ident ty = do
224− tu <- fresh
225− ru <- fresh
226− return $ replaceRowVars ident ru . replaceTypeVars ident tu $ ty
227−
228−replaceAllTypeSynonyms :: (D.Data d) => d -> Check d
229−replaceAllTypeSynonyms d = do
230− env <- getEnv
231− let syns = map (\((path, name), (args, _)) -> (Qualified path name, length args)) . M.toList $ typeSynonyms env
232− either throwError return $ saturateAllTypeSynonyms syns d
233−
234−desaturateAllTypeSynonyms :: (D.Data d) => d -> d
235−desaturateAllTypeSynonyms = everywhere (mkT replace)
236− where
237− replace (SaturatedTypeSynonym name args) = foldl TypeApp (TypeConstructor name) args
238− replace t = t
239−
240−expandAllTypeSynonyms :: Type -> Subst Check Type
241−expandAllTypeSynonyms (SaturatedTypeSynonym name args) = expandTypeSynonym name args >>= expandAllTypeSynonyms
242−expandAllTypeSynonyms ty = return ty
243−
244−expandTypeSynonym :: Qualified ProperName -> [Type] -> Subst Check Type
245−expandTypeSynonym name args = do
246− env <- lift getEnv
247− modulePath <- checkModulePath `fmap` lift get
248− case M.lookup (qualify modulePath name) (typeSynonyms env) of
249− Just (synArgs, body) -> return $ replaceAllTypeVars (zip synArgs args) body
250− Nothing -> error "Type synonym was not defined"
251−
252−ensureNoDuplicateProperties :: [(String, Value)] -> Check ()
253−ensureNoDuplicateProperties ps = guardWith "Duplicate property names" $ length (nub . map fst $ ps) == length ps
254−
255−infer :: M.Map Ident Type -> Value -> Subst Check Type
256−infer m val = rethrow (\e -> "Error inferring type of term " ++ prettyPrintValue val ++ ":\n" ++ e) $ do
257− ty <- infer' m val
258− escapeCheckLater ty
259− return ty
260−
261−infer' _ (NumericLiteral _) = return Number
262−infer' _ (StringLiteral _) = return String
263−infer' _ (BooleanLiteral _) = return Boolean
264−infer' m (ArrayLiteral vals) = do
265− ts <- mapM (infer m) vals
266− arr <- fresh
267− forM_ ts $ \t -> arr ~~ Array t
268− return arr
269−infer' m (Unary op val) = do
270− t <- infer m val
271− inferUnary op t
272−infer' m (Binary op left right) = do
273− t1 <- infer m left
274− t2 <- infer m right
275− inferBinary op t1 t2
276−infer' m (ObjectLiteral ps) = do
277− lift $ ensureNoDuplicateProperties ps
278− ts <- mapM (infer m . snd) ps
279− let fields = zipWith (\(name, _) t -> (name, t)) ps ts
280− return $ Object $ rowFromList (fields, REmpty)
281−infer' m (ObjectUpdate o ps) = do
282− lift $ ensureNoDuplicateProperties ps
283− row <- fresh
284− newTys <- zipWith (\(name, _) t -> (name, t)) ps <$> mapM (infer m . snd) ps
285− oldTys <- zip (map fst ps) <$> replicateM (length ps) fresh
286− check m o $ Object $ rowFromList (oldTys, row)
287− return $ Object $ rowFromList (newTys, row)
288−infer' m (Indexer index val) = do
289− el <- fresh
290− check m index Number
291− check m val (Array el)
292− return el
293−infer' m (Accessor prop val) = do
294− obj <- infer m val
295− propTy <- inferProperty obj prop
296− case propTy of
297− Nothing -> do
298− field <- fresh
299− rest <- fresh
300− obj `subsumes` Object (RCons prop field rest)
301− return field
302− Just ty -> return ty
303−infer' m (Abs args ret) = do
304− ts <- replicateM (length args) fresh
305− let m' = m `M.union` M.fromList (zip args ts)
306− body <- infer m' ret
307− return $ Function ts body
308−infer' m app@(App _ _) = do
309− let (f, argss) = unfoldApplication app
310− ft <- infer m f
311− ret <- fresh
312− checkFunctionApplications m ft argss ret
313− return ret
314−infer' m (Var var@(Qualified mp name)) = do
315− case mp of
316− ModulePath [] ->
317− case M.lookup name m of
318− Just ty -> lift $ replaceAllTypeSynonyms ty
319− Nothing -> lookupGlobal
320− _ -> lookupGlobal
321− where
322− lookupGlobal = do
323− env <- lift getEnv
324− modulePath <- checkModulePath `fmap` lift get
325− case M.lookup (qualify modulePath var) (names env) of
326− Nothing -> throwError $ show var ++ " is undefined"
327− Just (ty, _) -> lift $ replaceAllTypeSynonyms ty
328−infer' m (Block ss) = do
329− ret <- fresh
330− (allCodePathsReturn, _) <- checkBlock m M.empty ret ss
331− guardWith "Block is missing a return statement" allCodePathsReturn
332− return ret
333−infer' m (Constructor c) = do
334− env <- lift getEnv
335− modulePath <- checkModulePath `fmap` lift get
336− case M.lookup (qualify modulePath c) (dataConstructors env) of
337− Nothing -> throwError $ "Constructor " ++ show c ++ " is undefined"
338− Just ty -> lift $ replaceAllTypeSynonyms ty
339−infer' m (Case val binders) = do
340− t1 <- infer m val
341− ret <- fresh
342− checkBinders m t1 ret binders
343− return ret
344−infer' m (IfThenElse cond th el) = do
345− check m cond Boolean
346− t2 <- infer m th
347− t3 <- infer m el
348− t2 ~~ t3
349− return t2
350−infer' m (TypedValue val ty) = do
351− kind <- lift $ kindOf ty
352− guardWith ("Expected type of kind *, was " ++ prettyPrintKind kind) $ kind == Star
353− ty' <- lift $ replaceAllTypeSynonyms ty
354− check m val ty'
355− return ty'
356−
357−inferProperty :: Type -> String -> Subst Check (Maybe Type)
358−inferProperty (Object row) prop = do
359− let (props, _) = rowToList row
360− return $ lookup prop props
361−inferProperty (SaturatedTypeSynonym name args) prop = do
362− replaced <- expandTypeSynonym name args
363− inferProperty replaced prop
364−inferProperty (ForAll ident ty) prop = do
365− replaced <- replaceVarWithUnknown ident ty
366− inferProperty replaced prop
367−inferProperty _ prop = return Nothing
368−
369−inferUnary :: UnaryOperator -> Type -> Subst Check Type
370−inferUnary op val =
371− case fromMaybe (error "Invalid operator") $ lookup op unaryOps of
372− (valTy, resTy) -> do
373− val ~~ valTy
374− return resTy
375−
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
380− res ~~ resTy
381− check m val valTy
382−
383−unaryOps :: [(UnaryOperator, (Type, Type))]
384−unaryOps = [ (Negate, (Number, Number))
385− , (Not, (Boolean, Boolean))
386− , (BitwiseNot, (Number, Number))
387− ]
388−
389−inferBinary :: BinaryOperator -> Type -> Type -> Subst Check Type
390−inferBinary op left right | isEqualityTest op = do
391− left ~~ right
392− return Boolean
393−inferBinary op left right =
394− case fromMaybe (error "Invalid operator") $ lookup op binaryOps of
395− (valTy, resTy) -> do
396− left ~~ valTy
397− right ~~ valTy
398− return resTy
399−
400−checkBinary :: M.Map Ident Type -> BinaryOperator -> Value -> Value -> Type -> Subst Check ()
401−checkBinary m op left right res | isEqualityTest op = do
402− res ~~ Boolean
403− t1 <- infer m left
404− t2 <- infer m right
405− t1 ~~ t2
406−checkBinary m op left right res =
407− case fromMaybe (error "Invalid operator") $ lookup op binaryOps of
408− (valTy, resTy) -> do
409− res ~~ resTy
410− check m left valTy
411− check m right valTy
412−
413−isEqualityTest :: BinaryOperator -> Bool
414−isEqualityTest EqualTo = True
415−isEqualityTest NotEqualTo = True
416−isEqualityTest _ = False
417−
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))
437− ]
438−
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
446− env <- lift getEnv
447− modulePath <- checkModulePath `fmap` lift get
448− case M.lookup (qualify modulePath ctor) (dataConstructors env) of
449− Just ty -> do
450− ty `subsumes` val
451− return M.empty
452− _ -> throwError $ "Constructor " ++ show ctor ++ " is not defined"
453−inferBinder val (UnaryBinder ctor binder) = do
454− env <- lift getEnv
455− modulePath <- checkModulePath `fmap` lift get
456− case M.lookup (qualify modulePath ctor) (dataConstructors env) of
457− Just ty -> do
458− Function [obj] ret <- replaceAllVarsWithUnknowns ty
459− val `subsumes` ret
460− inferBinder obj binder
461− _ -> throwError $ "Constructor " ++ show ctor ++ " is not defined"
462−inferBinder val (ObjectBinder props) = do
463− row <- fresh
464− rest <- fresh
465− m1 <- inferRowProperties row rest props
466− val ~~ Object row
467− return m1
468− where
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
472− propTy <- fresh
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
477− el <- fresh
478− m1 <- M.unions <$> mapM (inferBinder el) binders
479− val ~~ Array el
480− case rest of
481− Nothing -> return m1
482− Just binder -> do
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
488−
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− check (m1 `M.union` m) cond Boolean
493− return m1
494−inferGuardedBinder m val b = inferBinder val b
495−
496−checkBinders :: M.Map Ident Type -> Type -> Type -> [(Binder, Value)] -> Subst Check ()
497−checkBinders _ _ _ [] = return ()
498−checkBinders m nval ret ((binder, val):bs) = do
499− m1 <- inferGuardedBinder m nval binder
500− check (m1 `M.union` m) val ret
501− checkBinders m nval ret bs
502−
503−assignVariable :: Ident -> M.Map Ident Type -> Subst Check ()
504−assignVariable name m =
505− case M.lookup name m of
506− Nothing -> return ()
507− Just _ -> throwError $ "Variable with name " ++ show name ++ " already exists."
508−
509−checkStatement :: M.Map Ident Type -> M.Map Ident Type -> Type -> Statement -> Subst Check (Bool, M.Map Ident Type)
510−checkStatement m mass ret (VariableIntroduction name val) = do
511− assignVariable name (m `M.union` mass)
512− t <- infer m val
513− return (False, M.insert name t mass)
514−checkStatement m mass ret (Assignment ident val) = do
515− t <- infer m val
516− case M.lookup ident mass of
517− Nothing -> throwError $ "No local variable with name " ++ show ident
518− Just ty -> do t ~~ ty
519− return (False, mass)
520−checkStatement m mass ret (While val inner) = do
521− check m val Boolean
522− (allCodePathsReturn, _) <- checkBlock m mass ret inner
523− return (allCodePathsReturn, mass)
524−checkStatement m mass ret (If ifst) = do
525− allCodePathsReturn <- checkIfStatement m mass ret ifst
526− return (allCodePathsReturn, mass)
527−checkStatement m mass ret (For ident start end inner) = do
528− assignVariable ident (m `M.union` mass)
529− check (m `M.union` mass) start Number
530− check (m `M.union` mass) end Number
531− let mass1 = M.insert ident Number mass
532− (allCodePathsReturn, _) <- checkBlock (m `M.union` mass1) mass1 ret inner
533− return (allCodePathsReturn, mass)
534−checkStatement m mass ret (ForEach ident vals inner) = do
535− assignVariable ident (m `M.union` mass)
536− val <- fresh
537− check (m `M.union` mass) vals (Array val)
538− let mass1 = M.insert ident val mass
539− (allCodePathsReturn, _) <- checkBlock (m `M.union` mass1) mass1 ret inner
540− guardWith "Cannot return from within a foreach block" $ not allCodePathsReturn
541− return (False, mass)
542−checkStatement m mass ret (Return val) = do
543− check (m `M.union` mass) val ret
544− return (True, mass)
545−
546−checkIfStatement :: M.Map Ident Type -> M.Map Ident Type -> Type -> IfStatement -> Subst Check Bool
547−checkIfStatement m mass ret (IfStatement val thens Nothing) = do
548− check m val Boolean
549− _ <- checkBlock m mass ret thens
550− return False
551−checkIfStatement m mass ret (IfStatement val thens (Just elses)) = do
552− check m val Boolean
553− (allCodePathsReturn1, _) <- checkBlock m mass ret thens
554− allCodePathsReturn2 <- checkElseStatement m mass ret elses
555− return $ allCodePathsReturn1 && allCodePathsReturn2
556−
557−checkElseStatement :: M.Map Ident Type -> M.Map Ident Type -> Type -> ElseStatement -> Subst Check Bool
558−checkElseStatement m mass ret (Else elses) = fst <$> checkBlock m mass ret elses
559−checkElseStatement m mass ret (ElseIf ifst) = checkIfStatement m mass ret ifst
560−
561−checkBlock :: M.Map Ident Type -> M.Map Ident Type -> Type -> [Statement] -> Subst Check (Bool, M.Map Ident Type)
562−checkBlock _ mass _ [] = return (False, mass)
563−checkBlock m mass ret (s:ss) = do
564− (b1, mass1) <- checkStatement (m `M.union` mass) mass ret s
565− case (b1, ss) of
566− (True, []) -> return (True, mass1)
567− (True, _) -> throwError "Unreachable code"
568− (False, ss) -> do
569− (b2, mass2) <- checkBlock m mass1 ret ss
570− return (b2, mass2)
571−
572−skolemize :: String -> Type -> Subst Check Type
573−skolemize ident ty = do
574− tsk <- Skolem <$> fresh'
575− rsk <- RSkolem <$> fresh'
576− return $ replaceRowVars ident rsk $ replaceTypeVars ident tsk ty
577−
578−check :: M.Map Ident Type -> Value -> Type -> Subst Check ()
579−check m val ty = rethrow errorMessage $ check' m val ty
580− where
581− errorMessage msg =
582− "Error checking type of term " ++
583− prettyPrintValue val ++
584− " against type " ++
585− prettyPrintType ty ++
586− ":\n" ++
587− msg
588−
589−check' :: M.Map Ident Type -> Value -> Type -> Subst Check ()
590−check' m val (ForAll idents ty) = do
591− sk <- skolemize idents ty
592− check m val sk
593−check' m val u@(TUnknown _) = do
594− ty <- infer m val
595− -- Don't unify an unknown with an inferred polytype
596− ty' <- replaceAllVarsWithUnknowns ty
597− ty' ~~ u
598−check' m (NumericLiteral _) Number = return ()
599−check' m (StringLiteral _) String = return ()
600−check' m (BooleanLiteral _) Boolean = return ()
601−check' m (Unary op val) ty = checkUnary m op val ty
602−check' m (Binary op left right) ty = checkBinary m op left right ty
603−check' m (ArrayLiteral vals) (Array ty) = forM_ vals (\val -> check m val ty)
604−check' m (Indexer index vals) ty = check m index Number >> check m vals (Array ty)
605−check' m (Abs args ret) (Function argTys retTy) = do
606− guardWith "Incorrect number of function arguments" (length args == length argTys)
607− let bindings = M.fromList (zip args argTys)
608− check (bindings `M.union` m) ret retTy
609−check' m app@(App _ _) ret = do
610− let (f, argss) = unfoldApplication app
611− ft <- infer m f
612− checkFunctionApplications m ft argss ret
613−check' m v@(Var var@(Qualified mp name)) ty = do
614− case mp of
615− ModulePath [] ->
616− case M.lookup name m of
617− Just ty1 -> do
618− repl <- lift $ replaceAllTypeSynonyms ty1
619− repl `subsumes` ty
620− Nothing -> lookupGlobal
621− _ -> lookupGlobal
622− where
623− lookupGlobal = do
624− env <- lift getEnv
625− modulePath <- checkModulePath `fmap` lift get
626− case M.lookup (qualify modulePath var) (names env) of
627− Nothing -> throwError $ show var ++ " is undefined"
628− Just (ty1, _) -> do
629− repl <- lift $ replaceAllTypeSynonyms ty1
630− repl `subsumes` ty
631−check' m (TypedValue val ty1) ty2 = do
632− kind <- lift $ kindOf ty1
633− guardWith ("Expected type of kind *, was " ++ prettyPrintKind kind) $ kind == Star
634− ty1 `subsumes` ty2
635− check m val ty1
636−check' m (Case val binders) ret = do
637− t1 <- infer m val
638− checkBinders m t1 ret binders
639−check' m (IfThenElse cond th el) ty = do
640− check m cond Boolean
641− check m th ty
642− check m el ty
643−check' m (ObjectLiteral ps) (Object row) = do
644− lift $ ensureNoDuplicateProperties ps
645− checkProperties m ps row False
646−check' m (ObjectUpdate obj ps) (Object row) = do
647− lift $ ensureNoDuplicateProperties ps
648− us <- zip (map fst ps) <$> replicateM (length ps) fresh
649− let (propsToCheck, rest) = rowToList row
650− propsToRemove = map fst ps
651− remainingProps = filter (\(p, _) -> p `notElem` propsToRemove) propsToCheck
652− check m obj (Object (rowFromList (us ++ remainingProps, rest)))
653− checkProperties m ps row True
654−check' m (Accessor prop val) ty = do
655− rest <- fresh
656− check m val (Object (RCons prop ty rest))
657−check' m (Block ss) ret = do
658− (allCodePathsReturn, _) <- checkBlock m M.empty ret ss
659− guardWith "Block is missing a return statement" allCodePathsReturn
660−check' m (Constructor c) ty = do
661− env <- lift getEnv
662− modulePath <- checkModulePath `fmap` lift get
663− case M.lookup (qualify modulePath c) (dataConstructors env) of
664− Nothing -> throwError $ "Constructor " ++ show c ++ " is undefined"
665− Just ty1 -> do
666− repl <- lift $ replaceAllTypeSynonyms ty1
667− repl `subsumes` ty
668−check' m val (SaturatedTypeSynonym name args) = do
669− ty <- expandTypeSynonym name args
670− check m val ty
671−check' _ val ty = throwError $ prettyPrintValue val ++ " does not have type " ++ prettyPrintType ty
672−
673−checkProperties :: M.Map Ident Type -> [(String, Value)] -> Row -> Bool -> Subst Check ()
674−checkProperties m ps row lax = let (ts, r') = rowToList row in go ps ts r' where
675− go [] [] REmpty = return ()
676− go [] [] u@(RUnknown _) = u ~~ REmpty
677− go [] [] (RSkolem _) | lax = return ()
678− go [] ((p, _): _) _ | lax = return ()
679− | otherwise = throwError $ prettyPrintValue (ObjectLiteral ps) ++ " does not have property " ++ p
680− go ((p,_):_) [] REmpty = throwError $ "Property " ++ p ++ " is not present in closed object type " ++ prettyPrintRow row
681− go ((p,v):ps) [] u@(RUnknown _) = do
682− ty <- infer m v
683− rest <- fresh
684− u ~~ RCons p ty rest
685− go ps [] rest
686− go ((p,v):ps) ts r =
687− case lookup p ts of
688− Nothing -> do
689− ty <- infer m v
690− rest <- fresh
691− r ~~ RCons p ty rest
692− go ps ts rest
693− Just ty -> do
694− check m v ty
695− go ps (delete (p, ty) ts) r
696− go _ _ _ = throwError $ prettyPrintValue (ObjectLiteral ps) ++ " does not have type " ++ prettyPrintType (Object row)
697−
698−unfoldApplication :: Value -> (Value, [[Value]])
699−unfoldApplication = go []
700− where
701− go argss (App f args) = go (args:argss) f
702− go argss f = (f, argss)
703−
704−checkFunctionApplications :: M.Map Ident Type -> Type -> [[Value]] -> Type -> Subst Check ()
705−checkFunctionApplications _ _ [] _ = error "Nullary function application"
706−checkFunctionApplications m fnTy [args] ret = checkFunctionApplication m fnTy args ret
707−checkFunctionApplications m fnTy (args:argss) ret = do
708− f <- fresh
709− checkFunctionApplication m fnTy args f
710− checkFunctionApplications m f argss ret
711−
712−checkFunctionApplication :: M.Map Ident Type -> Type -> [Value] -> Type -> Subst Check ()
713−checkFunctionApplication m fnTy args ret = rethrow errorMessage $ checkFunctionApplication' m fnTy args ret
714− where
715− errorMessage msg = "Error applying function of type "
716− ++ prettyPrintType fnTy
717− ++ " to arguments " ++ intercalate ", " (map prettyPrintValue args)
718− ++ ", expecting value of type "
719− ++ prettyPrintType ret ++ ":\n" ++ msg
720−
721−checkFunctionApplication' :: M.Map Ident Type -> Type -> [Value] -> Type -> Subst Check ()
722−checkFunctionApplication' m (Function argTys retTy) args ret = do
723− guardWith "Incorrect number of function arguments" (length args == length argTys)
724− zipWithM (check m) args argTys
725− retTy `subsumes` ret
726−checkFunctionApplication' m (ForAll ident ty) args ret = do
727− replaced <- replaceVarWithUnknown ident ty
728− checkFunctionApplication m replaced args ret
729−checkFunctionApplication' m u@(TUnknown _) args ret = do
730− tyArgs <- mapM (\arg -> infer m arg >>= replaceAllVarsWithUnknowns) args
731− u ~~ Function tyArgs ret
732−checkFunctionApplication' m (SaturatedTypeSynonym name tyArgs) args ret = do
733− ty <- expandTypeSynonym name tyArgs
734− checkFunctionApplication' m ty args ret
735−checkFunctionApplication' _ fnTy args ret = throwError $ "Cannot apply function of type "
736− ++ prettyPrintType fnTy
737− ++ " to arguments " ++ intercalate ", " (map prettyPrintValue args)
738− ++ ". Expecting value of type " ++ prettyPrintType ret ++ "."
739−
740−subsumes :: Type -> Type -> Subst Check ()
741−subsumes (ForAll ident ty1) ty2 = do
742− replaced <- replaceVarWithUnknown ident ty1
743− replaced `subsumes` ty2
744−subsumes (Function args1 ret1) (Function args2 ret2) = do
745− zipWithM subsumes args2 args1
746− ret1 `subsumes` ret2
747−subsumes ty1 ty2 = ty1 ~~ ty2
748−