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