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