@@ -1,731 +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−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) -> do
250− let m = M.fromList $ zip synArgs args
251− return $ replaceTypeVars m body
252− Nothing -> error "Type synonym was not defined"
253−
254−ensureNoDuplicateProperties :: [(String, Value)] -> Check ()
255−ensureNoDuplicateProperties ps = guardWith "Duplicate property names" $ length (nub . map fst $ ps) == length ps
256−
257−infer :: M.Map Ident Type -> Value -> Subst Check Type
258−infer m val = rethrow (\e -> "Error inferring type of term " ++ prettyPrintValue val ++ ":\n" ++ e) $ do
259− ty <- infer' m val
260− escapeCheckLater ty
261− return ty
262−
263−infer' _ (NumericLiteral _) = return Number
264−infer' _ (StringLiteral _) = return String
265−infer' _ (BooleanLiteral _) = return Boolean
266−infer' m (ArrayLiteral vals) = do
267− ts <- mapM (infer m) vals
268− arr <- fresh
269− forM_ ts $ \t -> arr ~~ Array t
270− return arr
271−infer' m (Unary op val) = do
272− t <- infer m val
273− inferUnary op t
274−infer' m (Binary op left right) = do
275− t1 <- infer m left
276− t2 <- infer m right
277− inferBinary op t1 t2
278−infer' m (ObjectLiteral ps) = do
279− lift $ ensureNoDuplicateProperties ps
280− ts <- mapM (infer m . snd) ps
281− let fields = zipWith (\(name, _) t -> (name, t)) ps ts
282− return $ Object $ typesToRow fields
283−infer' m (ObjectUpdate o ps) = do
284− lift $ ensureNoDuplicateProperties ps
285− obj <- infer m o
286− row <- fresh
287− ts <- mapM (infer m . snd) ps
288− let tys = zipWith (\(name, _) t -> (name, t)) ps ts
289− obj ~~ Object (rowFromList (tys, row))
290− return obj
291−infer' m (Indexer index val) = do
292− el <- fresh
293− check m index Number
294− check m val (Array el)
295− return el
296−infer' m (Accessor prop val) = do
297− field <- fresh
298− rest <- fresh
299− check m val (Object (RCons prop field rest))
300− return field
301−infer' m (Abs args ret) = do
302− ts <- replicateM (length args) fresh
303− let m' = m `M.union` M.fromList (zip args ts)
304− body <- infer m' ret
305− return $ Function ts body
306−infer' m app@(App _ _) = do
307− let (f, argss) = unfoldApplication app
308− ft <- infer m f
309− ret <- fresh
310− checkFunctionApplications m ft argss ret
311− return ret
312−infer' m (Var var@(Qualified mp name)) = do
313− case mp of
314− ModulePath [] ->
315− case M.lookup name m of
316− Just ty -> lift $ replaceAllTypeSynonyms ty
317− Nothing -> lookupGlobal
318− _ -> lookupGlobal
319− where
320− lookupGlobal = do
321− env <- lift getEnv
322− modulePath <- checkModulePath `fmap` lift get
323− case M.lookup (qualify modulePath var) (names env) of
324− Nothing -> throwError $ show var ++ " is undefined"
325− Just (ty, _) -> lift $ replaceAllTypeSynonyms ty
326−infer' m (Block ss) = do
327− ret <- fresh
328− (allCodePathsReturn, _) <- checkBlock m M.empty ret ss
329− guardWith "Block is missing a return statement" allCodePathsReturn
330− return ret
331−infer' m (Constructor c) = do
332− env <- lift getEnv
333− modulePath <- checkModulePath `fmap` lift get
334− case M.lookup (qualify modulePath c) (dataConstructors env) of
335− Nothing -> throwError $ "Constructor " ++ show c ++ " is undefined"
336− Just ty -> lift $ replaceAllTypeSynonyms ty
337−infer' m (Case val binders) = do
338− t1 <- infer m val
339− ret <- fresh
340− checkBinders m t1 ret binders
341− return ret
342−infer' m (IfThenElse cond th el) = do
343− check m cond Boolean
344− t2 <- infer m th
345− t3 <- infer m el
346− t2 ~~ t3
347− return t2
348−infer' m (TypedValue val ty) = do
349− kind <- lift $ kindOf ty
350− guardWith ("Expected type of kind *, was " ++ prettyPrintKind kind) $ kind == Star
351− ty' <- lift $ replaceAllTypeSynonyms ty
352− check m val ty'
353− return ty'
354−
355−inferUnary :: UnaryOperator -> Type -> Subst Check Type
356−inferUnary op val =
357− case fromMaybe (error "Invalid operator") $ lookup op unaryOps of
358− (valTy, resTy) -> do
359− val ~~ valTy
360− return resTy
361−
362−checkUnary :: M.Map Ident Type -> UnaryOperator -> Value -> Type -> Subst Check ()
363−checkUnary m op val res =
364− case fromMaybe (error "Invalid operator") $ lookup op unaryOps of
365− (valTy, resTy) -> do
366− res ~~ resTy
367− check m val valTy
368−
369−unaryOps :: [(UnaryOperator, (Type, Type))]
370−unaryOps = [ (Negate, (Number, Number))
371− , (Not, (Boolean, Boolean))
372− , (BitwiseNot, (Number, Number))
373− ]
374−
375−inferBinary :: BinaryOperator -> Type -> Type -> Subst Check Type
376−inferBinary op left right | isEqualityTest op = do
377− left ~~ right
378− return Boolean
379−inferBinary op left right =
380− case fromMaybe (error "Invalid operator") $ lookup op binaryOps of
381− (valTy, resTy) -> do
382− left ~~ valTy
383− right ~~ valTy
384− return resTy
385−
386−checkBinary :: M.Map Ident Type -> BinaryOperator -> Value -> Value -> Type -> Subst Check ()
387−checkBinary m op left right res | isEqualityTest op = do
388− res ~~ Boolean
389− t1 <- infer m left
390− t2 <- infer m right
391− t1 ~~ t2
392−checkBinary m op left right res =
393− case fromMaybe (error "Invalid operator") $ lookup op binaryOps of
394− (valTy, resTy) -> do
395− res ~~ resTy
396− check m left valTy
397− check m right valTy
398−
399−isEqualityTest :: BinaryOperator -> Bool
400−isEqualityTest EqualTo = True
401−isEqualityTest NotEqualTo = True
402−isEqualityTest _ = False
403−
404−binaryOps :: [(BinaryOperator, (Type, Type))]
405−binaryOps = [ (Add, (Number, Number))
406− , (Subtract, (Number, Number))
407− , (Multiply, (Number, Number))
408− , (Divide, (Number, Number))
409− , (Modulus, (Number, Number))
410− , (BitwiseAnd, (Number, Number))
411− , (BitwiseOr, (Number, Number))
412− , (BitwiseXor, (Number, Number))
413− , (ShiftRight, (Number, Number))
414− , (ZeroFillShiftRight, (Number, Number))
415− , (And, (Boolean, Boolean))
416− , (Or, (Boolean, Boolean))
417− , (Concat, (String, String))
418− , (Modulus, (Number, Number))
419− , (LessThan, (Number, Boolean))
420− , (LessThanOrEqualTo, (Number, Boolean))
421− , (GreaterThan, (Number, Boolean))
422− , (GreaterThanOrEqualTo, (Number, Boolean))
423− ]
424−
425−inferBinder :: Type -> Binder -> Subst Check (M.Map Ident Type)
426−inferBinder _ NullBinder = return M.empty
427−inferBinder val (StringBinder _) = val ~~ String >> return M.empty
428−inferBinder val (NumberBinder _) = val ~~ Number >> return M.empty
429−inferBinder val (BooleanBinder _) = val ~~ Boolean >> return M.empty
430−inferBinder val (VarBinder name) = return $ M.singleton name val
431−inferBinder val (NullaryBinder ctor) = do
432− env <- lift getEnv
433− modulePath <- checkModulePath `fmap` lift get
434− case M.lookup (qualify modulePath ctor) (dataConstructors env) of
435− Just ty -> do
436− ty `subsumes` val
437− return M.empty
438− _ -> throwError $ "Constructor " ++ show ctor ++ " is not defined"
439−inferBinder val (UnaryBinder ctor binder) = do
440− env <- lift getEnv
441− modulePath <- checkModulePath `fmap` lift get
442− case M.lookup (qualify modulePath ctor) (dataConstructors env) of
443− Just ty -> do
444− obj <- fresh
445− ty `subsumes` (Function [obj] val)
446− inferBinder obj binder
447− _ -> throwError $ "Constructor " ++ show ctor ++ " is not defined"
448−inferBinder val (ObjectBinder props) = do
449− row <- fresh
450− rest <- fresh
451− m1 <- inferRowProperties row rest props
452− val ~~ Object row
453− return m1
454− where
455− inferRowProperties :: Row -> Row -> [(String, Binder)] -> Subst Check (M.Map Ident Type)
456− inferRowProperties nrow row [] = nrow ~~ row >> return M.empty
457− inferRowProperties nrow row ((name, binder):binders) = do
458− propTy <- fresh
459− m1 <- inferBinder propTy binder
460− m2 <- inferRowProperties nrow (RCons name propTy row) binders
461− return $ m1 `M.union` m2
462−inferBinder val (ArrayBinder binders rest) = do
463− el <- fresh
464− m1 <- M.unions <$> mapM (inferBinder el) binders
465− val ~~ Array el
466− case rest of
467− Nothing -> return m1
468− Just binder -> do
469− m2 <- inferBinder val binder
470− return $ m1 `M.union` m2
471−inferBinder val (NamedBinder name binder) = do
472− m <- inferBinder val binder
473− return $ M.insert name val m
474−
475−inferGuardedBinder :: M.Map Ident Type -> Type -> Binder -> Subst Check (M.Map Ident Type)
476−inferGuardedBinder m val (GuardedBinder cond binder) = do
477− m1 <- inferBinder val binder
478− ty <- infer (m `M.union` m1) cond
479− ty ~~ Boolean
480− return m1
481−inferGuardedBinder m val b = inferBinder val b
482−
483−checkBinders :: M.Map Ident Type -> Type -> Type -> [(Binder, Value)] -> Subst Check ()
484−checkBinders _ _ _ [] = return ()
485−checkBinders m nval ret ((binder, val):bs) = do
486− m1 <- inferGuardedBinder m nval binder
487− check (m `M.union` m1) val ret
488− checkBinders m nval ret bs
489−
490−assignVariable :: Ident -> M.Map Ident Type -> Subst Check ()
491−assignVariable name m =
492− case M.lookup name m of
493− Nothing -> return ()
494− Just _ -> throwError $ "Variable with name " ++ show name ++ " already exists."
495−
496−checkStatement :: M.Map Ident Type -> M.Map Ident Type -> Type -> Statement -> Subst Check (Bool, M.Map Ident Type)
497−checkStatement m mass ret (VariableIntroduction name val) = do
498− assignVariable name (m `M.union` mass)
499− t <- infer m val
500− return (False, M.insert name t mass)
501−checkStatement m mass ret (Assignment ident val) = do
502− t <- infer m val
503− case M.lookup ident mass of
504− Nothing -> throwError $ "No local variable with name " ++ show ident
505− Just ty -> do t ~~ ty
506− return (False, mass)
507−checkStatement m mass ret (While val inner) = do
508− check m val Boolean
509− (allCodePathsReturn, _) <- checkBlock m mass ret inner
510− return (allCodePathsReturn, mass)
511−checkStatement m mass ret (If ifst) = do
512− allCodePathsReturn <- checkIfStatement m mass ret ifst
513− return (allCodePathsReturn, mass)
514−checkStatement m mass ret (For ident start end inner) = do
515− assignVariable ident (m `M.union` mass)
516− check (m `M.union` mass) start Number
517− check (m `M.union` mass) end Number
518− let mass1 = M.insert ident Number mass
519− (allCodePathsReturn, _) <- checkBlock (m `M.union` mass1) mass1 ret inner
520− return (allCodePathsReturn, mass)
521−checkStatement m mass ret (ForEach ident vals inner) = do
522− assignVariable ident (m `M.union` mass)
523− val <- fresh
524− check (m `M.union` mass) vals (Array val)
525− let mass1 = M.insert ident val mass
526− (allCodePathsReturn, _) <- checkBlock (m `M.union` mass1) mass1 ret inner
527− guardWith "Cannot return from within a foreach block" $ not allCodePathsReturn
528− return (False, mass)
529−checkStatement m mass ret (Return val) = do
530− check (m `M.union` mass) val ret
531− return (True, mass)
532−
533−checkIfStatement :: M.Map Ident Type -> M.Map Ident Type -> Type -> IfStatement -> Subst Check Bool
534−checkIfStatement m mass ret (IfStatement val thens Nothing) = do
535− check m val Boolean
536− _ <- checkBlock m mass ret thens
537− return False
538−checkIfStatement m mass ret (IfStatement val thens (Just elses)) = do
539− check m val Boolean
540− (allCodePathsReturn1, _) <- checkBlock m mass ret thens
541− allCodePathsReturn2 <- checkElseStatement m mass ret elses
542− return $ allCodePathsReturn1 && allCodePathsReturn2
543−
544−checkElseStatement :: M.Map Ident Type -> M.Map Ident Type -> Type -> ElseStatement -> Subst Check Bool
545−checkElseStatement m mass ret (Else elses) = fst <$> checkBlock m mass ret elses
546−checkElseStatement m mass ret (ElseIf ifst) = checkIfStatement m mass ret ifst
547−
548−checkBlock :: M.Map Ident Type -> M.Map Ident Type -> Type -> [Statement] -> Subst Check (Bool, M.Map Ident Type)
549−checkBlock _ mass _ [] = return (False, mass)
550−checkBlock m mass ret (s:ss) = do
551− (b1, mass1) <- checkStatement (m `M.union` mass) mass ret s
552− case (b1, ss) of
553− (True, []) -> return (True, mass1)
554− (True, _) -> throwError "Unreachable code"
555− (False, ss) -> do
556− (b2, mass2) <- checkBlock m mass1 ret ss
557− return (b2, mass2)
558−
559−skolemize :: String -> Type -> Subst Check Type
560−skolemize ident ty = do
561− tsk <- Skolem <$> fresh'
562− rsk <- RSkolem <$> fresh'
563− return $ replaceRowVars (M.singleton ident rsk) $ replaceTypeVars (M.singleton ident tsk) ty
564−
565−check :: M.Map Ident Type -> Value -> Type -> Subst Check ()
566−check m val ty = rethrow errorMessage $ check' m val ty
567− where
568− errorMessage msg =
569− "Error checking type of term " ++
570− prettyPrintValue val ++
571− " against type " ++
572− prettyPrintType ty ++
573− ":\n" ++
574− msg
575−
576−check' :: M.Map Ident Type -> Value -> Type -> Subst Check ()
577−check' m val (ForAll idents ty) = do
578− sk <- skolemize idents ty
579− check m val sk
580−check' m val u@(TUnknown _) = do
581− ty <- infer m val
582− -- Don't unify an unknown with an inferred polytype
583− ty' <- replaceAllVarsWithUnknowns ty
584− ty' ~~ u
585−check' m (NumericLiteral _) Number = return ()
586−check' m (StringLiteral _) String = return ()
587−check' m (BooleanLiteral _) Boolean = return ()
588−check' m (Unary op val) ty = checkUnary m op val ty
589−check' m (Binary op left right) ty = checkBinary m op left right ty
590−check' m (ArrayLiteral vals) (Array ty) = forM_ vals (\val -> check m val ty)
591−check' m (Indexer index vals) ty = check m index Number >> check m vals (Array ty)
592−check' m (Abs args ret) (Function argTys retTy) = do
593− guardWith "Incorrect number of function arguments" (length args == length argTys)
594− let bindings = M.fromList (zip args argTys)
595− check (bindings `M.union` m) ret retTy
596−check' m app@(App _ _) ret = do
597− let (f, argss) = unfoldApplication app
598− ft <- infer m f
599− checkFunctionApplications m ft argss ret
600−check' m v@(Var var@(Qualified mp name)) ty = do
601− case mp of
602− ModulePath [] ->
603− case M.lookup name m of
604− Just ty1 -> do
605− repl <- lift $ replaceAllTypeSynonyms ty1
606− repl `subsumes` ty
607− Nothing -> lookupGlobal
608− _ -> lookupGlobal
609− where
610− lookupGlobal = do
611− env <- lift getEnv
612− modulePath <- checkModulePath `fmap` lift get
613− case M.lookup (qualify modulePath var) (names env) of
614− Nothing -> throwError $ show var ++ " is undefined"
615− Just (ty1, _) -> do
616− repl <- lift $ replaceAllTypeSynonyms ty1
617− repl `subsumes` ty
618−check' m (TypedValue val ty1) ty2 = do
619− kind <- lift $ kindOf ty1
620− guardWith ("Expected type of kind *, was " ++ prettyPrintKind kind) $ kind == Star
621− ty1 `subsumes` ty2
622− check m val ty1
623−check' m (Case val binders) ret = do
624− t1 <- infer m val
625− checkBinders m t1 ret binders
626−check' m (IfThenElse cond th el) ty = do
627− check m cond Boolean
628− check m th ty
629− check m el ty
630−check' m (ObjectLiteral ps) (Object row) = do
631− lift $ ensureNoDuplicateProperties ps
632− checkProperties m ps row False
633−check' m (ObjectUpdate obj ps) objTy@(Object row) = do
634− lift $ ensureNoDuplicateProperties ps
635− check m obj objTy
636− checkProperties m ps row True
637−check' m (Accessor prop val) ty = do
638− rest <- fresh
639− check m val (Object (RCons prop ty rest))
640−check' m (Block ss) ret = do
641− (allCodePathsReturn, _) <- checkBlock m M.empty ret ss
642− guardWith "Block is missing a return statement" allCodePathsReturn
643−check' m (Constructor c) ty = do
644− env <- lift getEnv
645− modulePath <- checkModulePath `fmap` lift get
646− case M.lookup (qualify modulePath c) (dataConstructors env) of
647− Nothing -> throwError $ "Constructor " ++ show c ++ " is undefined"
648− Just ty1 -> do
649− repl <- lift $ replaceAllTypeSynonyms ty1
650− repl `subsumes` ty
651−check' m val (SaturatedTypeSynonym name args) = do
652− ty <- expandTypeSynonym name args
653− check m val 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' m (SaturatedTypeSynonym name tyArgs) args ret = do
716− ty <- expandTypeSynonym name tyArgs
717− checkFunctionApplication' m ty args ret
718−checkFunctionApplication' _ fnTy args ret = throwError $ "Cannot apply function of type "
719− ++ prettyPrintType fnTy
720− ++ " to arguments " ++ intercalate ", " (map prettyPrintValue args)
721− ++ ". Expecting value of type " ++ prettyPrintType ret ++ "."
722−
723−subsumes :: Type -> Type -> Subst Check ()
724−subsumes (ForAll ident ty1) ty2 = do
725− replaced <- replaceVarsWithUnknowns [ident] ty1
726− replaced `subsumes` ty2
727−subsumes (Function args1 ret1) (Function args2 ret2) = do
728− zipWithM subsumes args2 args1
729− ret1 `subsumes` ret2
730−subsumes ty1 ty2 = ty1 ~~ ty2
731−