@@ -1,743 +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−{-# OPTIONS_GHC -fno-warn-orphans #-}
16−{-# LANGUAGE DeriveDataTypeable, FlexibleContexts #-}
17−
18−module Language.PureScript.TypeChecker.Types (
19− typesOf
20−) where
21−
22−import Data.List
23−import Data.Maybe (isNothing, isJust, fromMaybe)
24−import qualified Data.Data as D
25−import Data.Generics (everything, mkT, something, everywhere, mkQ)
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−import Control.Monad.Reader
40−
41−import Control.Applicative
42−import Control.Arrow (Arrow(..))
43−
44−import qualified Data.Map as M
45−import Data.Function (on)
46−
47−instance Unifiable Type where
48− unknown = TUnknown
49− isUnknown (TUnknown u) = Just u
50− isUnknown _ = Nothing
51− (~~) = unifyTypes
52− apply s (TUnknown u) = runSubstitution s u
53− apply s (SaturatedTypeSynonym name tys) = SaturatedTypeSynonym name $ map (apply s) tys
54− apply s (ForAll idents ty) = ForAll idents $ apply s ty
55− apply s (Array t) = Array (apply s t)
56− apply s (Object r) = Object (apply s r)
57− apply s (Function args ret) = Function (map (apply s) args) (apply s ret)
58− apply s (TypeApp t1 t2) = TypeApp (apply s t1) (apply s t2)
59− apply s (RCons name ty r) = RCons name (apply s ty) (apply s r)
60− apply _ t = t
61− unknowns (TUnknown (Unknown u)) = [u]
62− unknowns (SaturatedTypeSynonym _ tys) = concatMap unknowns tys
63− unknowns (ForAll _ 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 (RCons _ ty r) = unknowns ty ++ unknowns r
69− unknowns _ = []
70−
71−unifyTypes :: Type -> Type -> Subst ()
72−unifyTypes t1 t2 = rethrow (\e -> "Error unifying type " ++ prettyPrintType t1 ++ " with type " ++ prettyPrintType t2 ++ ":\n" ++ e) $ do
73− unifyTypes' t1 t2
74− where
75− unifyTypes' (TUnknown u1) (TUnknown u2) | u1 == u2 = return ()
76− unifyTypes' (TUnknown u) t = replace u t
77− unifyTypes' t (TUnknown u) = replace u t
78− unifyTypes' (SaturatedTypeSynonym name args) ty = do
79− ty1 <- expandTypeSynonym name args
80− ty1 `unifyTypes` ty
81− unifyTypes' ty s@(SaturatedTypeSynonym _ _) = s `unifyTypes` ty
82− unifyTypes' (ForAll ident1 ty1) (ForAll ident2 ty2) = do
83− sk <- skolemize ident1 ty1
84− replaced <- replaceVarWithUnknown ident2 ty2
85− sk `unifyTypes` replaced
86− unifyTypes' (ForAll ident ty1) ty2 = do
87− sk <- skolemize ident ty1
88− sk `unifyTypes` ty2
89− unifyTypes' ty f@(ForAll _ _) = f `unifyTypes` ty
90− unifyTypes' Number Number = return ()
91− unifyTypes' String String = return ()
92− unifyTypes' Boolean Boolean = return ()
93− unifyTypes' (Array s) (Array t) = s `unifyTypes` t
94− unifyTypes' (Object row1) (Object row2) = row1 ~~ row2
95− unifyTypes' (Function args1 ret1) (Function args2 ret2) = do
96− guardWith "Function applied to incorrect number of args" $ length args1 == length args2
97− zipWithM_ unifyTypes args1 args2
98− ret1 `unifyTypes` ret2
99− unifyTypes' (TypeVar v1) (TypeVar v2) | v1 == v2 = return ()
100− unifyTypes' (TypeConstructor c1) (TypeConstructor c2) = do
101− env <- getEnv
102− moduleName <- substCurrentModule `fmap` ask
103− guardWith ("Cannot unify " ++ show c1 ++ " with " ++ show c2 ++ ".") (typeConstructorsAreEqual env moduleName c1 c2)
104− unifyTypes' (TypeApp t3 t4) (TypeApp t5 t6) = do
105− t3 `unifyTypes` t5
106− t4 `unifyTypes` t6
107− unifyTypes' (Skolem s1) (Skolem s2) | s1 == s2 = return ()
108− unifyTypes' r1@(RCons _ _ _) r2 = unifyRows r1 r2
109− unifyTypes' r1 r2@(RCons _ _ _) = unifyRows r1 r2
110− unifyTypes' r1@REmpty r2 = unifyRows r1 r2
111− unifyTypes' r1 r2@REmpty = unifyRows r1 r2
112− unifyTypes' t3 t4 = throwError $ "Cannot unify " ++ prettyPrintType t3 ++ " with " ++ prettyPrintType t4 ++ "."
113−
114−unifyRows :: Type -> Type -> Subst ()
115−unifyRows r1 r2 =
116− let
117− (s1, r1') = rowToList r1
118− (s2, r2') = rowToList r2
119− int = [ (t1, t2) | (name, t1) <- s1, (name', t2) <- s2, name == name' ]
120− sd1 = [ (name, t1) | (name, t1) <- s1, name `notElem` map fst s2 ]
121− sd2 = [ (name, t2) | (name, t2) <- s2, name `notElem` map fst s1 ]
122− in do
123− forM_ int (uncurry (~~))
124− unifyRows' sd1 r1' sd2 r2'
125− where
126− unifyRows' :: [(String, Type)] -> Type -> [(String, Type)] -> Type -> Subst ()
127− unifyRows' [] (TUnknown u) sd r = replace u (rowFromList (sd, r))
128− unifyRows' sd r [] (TUnknown u) = replace u (rowFromList (sd, r))
129− unifyRows' ((name, ty):row) r others u@(TUnknown un) = do
130− occursCheck un ty
131− forM_ row $ \(_, t) -> occursCheck un t
132− u' <- fresh
133− u ~~ RCons name ty u'
134− unifyRows' row r others u'
135− unifyRows' [] REmpty [] REmpty = return ()
136− unifyRows' [] (TypeVar v1) [] (TypeVar v2) | v1 == v2 = return ()
137− unifyRows' [] (Skolem s1) [] (Skolem s2) | s1 == s2 = return ()
138− unifyRows' sd3 r3 sd4 r4 = throwError $ "Cannot unify " ++ prettyPrintRow (rowFromList (sd3, r3)) ++ " with " ++ prettyPrintRow (rowFromList (sd4, r4)) ++ "."
139−
140−typeConstructorsAreEqual :: Environment -> ModuleName -> Qualified ProperName -> Qualified ProperName -> Bool
141−typeConstructorsAreEqual env moduleName = (==) `on` canonicalizeType moduleName env
142−
143−typesOf :: ModuleName -> [(Ident, Value)] -> Check [Type]
144−typesOf moduleName vals = do
145− (tys, _) <- runSubst (SubstContext moduleName) $ do
146− let es = map isTyped vals
147− typed = filter (isJust . snd . snd) es
148− untyped = filter (isNothing . snd . snd) es
149− typedDict = map (\(ident, (_, Just ty)) -> (ident, ty)) typed
150− untypedNames <- replicateM (length untyped) fresh
151− let untypedDict = zip (map fst untyped) untypedNames
152− dict = M.fromList (map (\(ident, ty) -> ((moduleName, ident), (ty, LocalVariable))) $ typedDict ++ untypedDict)
153− tys <- forM es $ \e -> do
154− (val, ty) <- case e of
155− (_, (val, Just ty)) -> do
156− kind <- liftCheck $ kindOf moduleName ty
157− guardWith ("Expected type of kind *, was " ++ prettyPrintKind kind) $ kind == Star
158− ty' <- replaceAllTypeSynonyms ty
159− val' <- bindNames dict $ check val ty'
160− return (val', ty')
161− (ident, (val, Nothing)) -> do
162− TypedValue val' ty <- bindNames dict $ infer val
163− ty ~~ fromMaybe (error "name not found in dictionary") (lookup ident untypedDict)
164− return (val', ty)
165− when (moduleName == ModuleName (ProperName "Main") && fst e == Ident "main") $ do
166− [eff, a] <- replicateM 2 fresh
167− ty ~~ TypeApp (TypeApp (TypeConstructor (Qualified (Just (ModuleName (ProperName "Eff"))) (ProperName "Eff"))) eff) a
168− escapeCheck val ty
169− return ty
170− return tys
171− forM_ tys $ skolemEscapeCheck
172− return $ map (varIfUnknown . desaturateAllTypeSynonyms . setifyAll) tys
173−
174−isTyped :: (Ident, Value) -> (Ident, (Value, Maybe Type))
175−isTyped (name, TypedValue value ty) = (name, (value, Just ty))
176−isTyped (name, value) = (name, (value, Nothing))
177−
178−escapeCheck :: Value -> Type -> Subst ()
179−escapeCheck value ty = do
180− subst <- substSubst <$> getSubstState
181− let visibleUnknowns = nub $ unknowns $ apply subst ty
182− let allUnknowns = findAllTypes value
183− forM_ allUnknowns $ \t -> do
184− let unsolvedUnknowns = nub . unknowns $ apply subst t
185− guardWith "Escape check fails" $ null $ unsolvedUnknowns \\ visibleUnknowns
186−
187−findAllTypes :: Value -> [Type]
188−findAllTypes = everything (++) (mkQ [] go)
189− where
190− go (TypedValue _ ty) = [ty]
191− go _ = []
192−
193−skolemEscapeCheck :: Type -> Check ()
194−skolemEscapeCheck ty =
195− case something (mkQ Nothing findSkolems) ty of
196− Nothing -> return ()
197− Just _ -> throwError $ "Skolem variables cannot escape. Consider adding a type signature." ++ show ty
198− where
199− findSkolems (Skolem _) = return ()
200− findSkolems _ = mzero
201−
202−setify :: Type -> Type
203−setify = rowFromList . first (M.toList . M.fromList) . rowToList
204−
205−setifyAll :: (D.Data d) => d -> d
206−setifyAll = everywhere (mkT setify)
207−
208−varIfUnknown :: Type -> Type
209−varIfUnknown ty =
210− let unks = nub $ unknowns ty
211− toName = (:) 't' . show
212− ty' = everywhere (mkT typeToVar) $ ty
213− typeToVar :: Type -> Type
214− typeToVar (TUnknown (Unknown u)) = TypeVar (toName u)
215− typeToVar t = t
216− in mkForAll (sort . map toName $ unks) ty'
217−
218−replaceAllTypeVars :: (D.Data d) => [(String, Type)] -> d -> d
219−replaceAllTypeVars = foldl' (\f (name, ty) -> replaceTypeVars name ty . f) id
220−
221−replaceAllVarsWithUnknowns :: Type -> Subst Type
222−replaceAllVarsWithUnknowns (ForAll ident ty) = replaceVarWithUnknown ident ty >>= replaceAllVarsWithUnknowns
223−replaceAllVarsWithUnknowns ty = return ty
224−
225−replaceVarWithUnknown :: String -> Type -> Subst Type
226−replaceVarWithUnknown ident ty = do
227− tu <- fresh
228− return $ replaceTypeVars ident tu $ ty
229−
230−replaceAllTypeSynonyms :: (Functor m, MonadState CheckState m, MonadReader SubstContext m, MonadError String m) => (D.Data d) => d -> m d
231−replaceAllTypeSynonyms d = do
232− env <- getEnv
233− moduleName <- substCurrentModule <$> ask
234− let syns = map (\((path, name), (args, _)) -> ((path, name), length args)) . M.toList $ typeSynonyms env
235− either throwError return $ saturateAllTypeSynonyms env moduleName syns d
236−
237−desaturateAllTypeSynonyms :: (D.Data d) => d -> d
238−desaturateAllTypeSynonyms = everywhere (mkT replaceSaturatedTypeSynonym)
239− where
240− replaceSaturatedTypeSynonym (SaturatedTypeSynonym name args) = foldl TypeApp (TypeConstructor name) args
241− replaceSaturatedTypeSynonym t = t
242−
243−expandTypeSynonym :: Qualified ProperName -> [Type] -> Subst Type
244−expandTypeSynonym name args = do
245− env <- getEnv
246− moduleName <- substCurrentModule `fmap` ask
247− case M.lookup (canonicalizeType moduleName env name) (typeSynonyms env) of
248− Just (synArgs, body) -> return $ replaceAllTypeVars (zip synArgs args) body
249− Nothing -> error "Type synonym was not defined"
250−
251−ensureNoDuplicateProperties :: (MonadError String m) => [(String, Value)] -> m ()
252−ensureNoDuplicateProperties ps = guardWith "Duplicate property names" $ length (nub . map fst $ ps) == length ps
253−
254−infer :: Value -> Subst Value
255−infer val = rethrow (\e -> "Error inferring type of term " ++ prettyPrintValue val ++ ":\n" ++ e) $ infer' val
256−
257−infer' :: Value -> Subst Value
258−infer' v@(NumericLiteral _) = return $ TypedValue v Number
259−infer' v@(StringLiteral _) = return $ TypedValue v String
260−infer' v@(BooleanLiteral _) = return $ TypedValue v Boolean
261−infer' (ArrayLiteral vals) = do
262− ts <- mapM infer vals
263− els <- fresh
264− forM_ ts $ \(TypedValue _ t) -> els ~~ Array t
265− return $ TypedValue (ArrayLiteral ts) els
266−infer' (Unary op val) = do
267− v <- infer val
268− inferUnary op v
269−infer' (Binary op left right) = do
270− v1 <- infer left
271− v2 <- infer right
272− inferBinary op v1 v2
273−infer' (ObjectLiteral ps) = do
274− ensureNoDuplicateProperties ps
275− ts <- mapM (infer . snd) ps
276− let fields = zipWith (\name (TypedValue _ t) -> (name, t)) (map fst ps) ts
277− ty = Object $ rowFromList (fields, REmpty)
278− return $ TypedValue (ObjectLiteral (zip (map fst ps) ts)) ty
279−infer' (ObjectUpdate o ps) = do
280− ensureNoDuplicateProperties ps
281− row <- fresh
282− newVals <- zipWith (\(name, _) t -> (name, t)) ps <$> mapM (infer . snd) ps
283− let newTys = map (\(name, TypedValue _ ty) -> (name, ty)) newVals
284− oldTys <- zip (map fst ps) <$> replicateM (length ps) fresh
285− o' <- check o $ Object $ rowFromList (oldTys, row)
286− return $ TypedValue (ObjectUpdate o' newVals) $ Object $ rowFromList (newTys, row)
287−infer' (Indexer index val) = do
288− el <- fresh
289− index' <- check index Number
290− val' <- check val (Array el)
291− return $ TypedValue (Indexer (TypedValue index' Number) (TypedValue val' (Array el))) el
292−infer' (Accessor prop val) = do
293− typed@(TypedValue _ objTy) <- infer val
294− propTy <- inferProperty objTy prop
295− case propTy of
296− Nothing -> do
297− field <- fresh
298− rest <- fresh
299− objTy `subsumes` Object (RCons prop field rest)
300− return $ TypedValue (Accessor prop typed) field
301− Just ty -> return $ TypedValue (Accessor prop typed) ty
302−infer' (Abs args ret) = do
303− ts <- replicateM (length args) fresh
304− moduleName <- substCurrentModule <$> ask
305− bindLocalVariables moduleName (zip args ts) $ do
306− (TypedValue body bodyTy) <- infer' ret
307− return $ TypedValue (Abs args body) $ Function ts bodyTy
308−infer' (App f args) = do
309− (TypedValue f' ft) <- infer f
310− ret <- fresh
311− args' <- checkFunctionApplication ft args ret
312− return $ TypedValue (App f' args') ret
313−infer' (Var var) = do
314− moduleName <- substCurrentModule <$> ask
315− ty <- lookupVariable moduleName var
316− ty' <- replaceAllTypeSynonyms ty
317− return $ TypedValue (Var var) ty'
318−infer' (Block ss) = do
319− ret <- fresh
320− (allCodePathsReturn, _, ss') <- checkBlock M.empty ret ss
321− guardWith "Block is missing a return statement" allCodePathsReturn
322− return $ TypedValue (Block ss') ret
323−infer' v@(Constructor c) = do
324− env <- getEnv
325− moduleName <- substCurrentModule `fmap` ask
326− case M.lookup (qualify moduleName c) (dataConstructors env) of
327− Nothing -> throwError $ "Constructor " ++ show c ++ " is undefined"
328− Just (ty, _) -> do ty' <- replaceAllTypeSynonyms ty
329− return $ TypedValue v ty'
330−infer' (Case vals binders) = do
331− ts <- mapM infer vals
332− ret <- fresh
333− binders' <- checkBinders (map (\(TypedValue _ t) -> t) ts) ret binders
334− return $ TypedValue (Case ts binders') ret
335−infer' (IfThenElse cond th el) = do
336− cond' <- check cond Boolean
337− v2@(TypedValue _ t2) <- infer th
338− v3@(TypedValue _ t3) <- infer el
339− t2 ~~ t3
340− return $ TypedValue (IfThenElse cond' v2 v3) t2
341−infer' (TypedValue val ty) = do
342− moduleName <- substCurrentModule <$> ask
343− kind <- liftCheck $ kindOf moduleName ty
344− guardWith ("Expected type of kind *, was " ++ prettyPrintKind kind) $ kind == Star
345− ty' <- replaceAllTypeSynonyms ty
346− check val ty'
347−infer' _ = error "Invalid argument to infer"
348−
349−inferProperty :: Type -> String -> Subst (Maybe Type)
350−inferProperty (Object row) prop = do
351− let (props, _) = rowToList row
352− return $ lookup prop props
353−inferProperty (SaturatedTypeSynonym name args) prop = do
354− replaced <- expandTypeSynonym name args
355− inferProperty replaced prop
356−inferProperty (ForAll ident ty) prop = do
357− replaced <- replaceVarWithUnknown ident ty
358− inferProperty replaced prop
359−inferProperty _ _ = return Nothing
360−
361−inferUnary :: UnaryOperator -> Value -> Subst Value
362−inferUnary op (TypedValue val valTy) =
363− case fromMaybe (error "Invalid operator") $ lookup op unaryOps of
364− (valTy', resTy) -> do
365− valTy' ~~ valTy
366− return $ TypedValue (Unary op val) resTy
367−inferUnary _ _ = error "Invalid arguments to inferUnary"
368−
369−checkUnary :: UnaryOperator -> Value -> Type -> Subst Value
370−checkUnary op val res =
371− case fromMaybe (error "Invalid operator") $ lookup op unaryOps of
372− (valTy, resTy) -> do
373− res ~~ resTy
374− val' <- check val valTy
375− return $ Unary op val'
376−
377−unaryOps :: [(UnaryOperator, (Type, Type))]
378−unaryOps = [ (Negate, (Number, Number))
379− , (Not, (Boolean, Boolean))
380− , (BitwiseNot, (Number, Number))
381− ]
382−
383−inferBinary :: BinaryOperator -> Value -> Value -> Subst Value
384−inferBinary op left@(TypedValue _ leftTy) right@(TypedValue _ rightTy) | isEqualityTest op = do
385− leftTy ~~ rightTy
386− return $ TypedValue (Binary op left right) Boolean
387−inferBinary op left@(TypedValue _ leftTy) right@(TypedValue _ rightTy) =
388− case fromMaybe (error "Invalid operator") $ lookup op binaryOps of
389− (valTy, resTy) -> do
390− leftTy ~~ valTy
391− rightTy ~~ valTy
392− return $ TypedValue (Binary op left right) resTy
393−inferBinary _ _ _ = error "Invalid arguments to inferBinary"
394−
395−checkBinary :: BinaryOperator -> Value -> Value -> Type -> Subst Value
396−checkBinary op left right res | isEqualityTest op = do
397− res ~~ Boolean
398− left'@(TypedValue _ t1) <- infer left
399− right'@(TypedValue _ t2) <- infer right
400− t1 ~~ t2
401− return $ Binary op left' right'
402−checkBinary op left right res =
403− case fromMaybe (error "Invalid operator") $ lookup op binaryOps of
404− (valTy, resTy) -> do
405− res ~~ resTy
406− left' <- check left valTy
407− right' <- check right valTy
408− return $ Binary op left' right'
409−
410−isEqualityTest :: BinaryOperator -> Bool
411−isEqualityTest EqualTo = True
412−isEqualityTest NotEqualTo = True
413−isEqualityTest _ = False
414−
415−binaryOps :: [(BinaryOperator, (Type, Type))]
416−binaryOps = [ (Add, (Number, Number))
417− , (Subtract, (Number, Number))
418− , (Multiply, (Number, Number))
419− , (Divide, (Number, Number))
420− , (Modulus, (Number, Number))
421− , (BitwiseAnd, (Number, Number))
422− , (BitwiseOr, (Number, Number))
423− , (BitwiseXor, (Number, Number))
424− , (ShiftRight, (Number, Number))
425− , (ZeroFillShiftRight, (Number, Number))
426− , (And, (Boolean, Boolean))
427− , (Or, (Boolean, Boolean))
428− , (Concat, (String, String))
429− , (Modulus, (Number, Number))
430− , (LessThan, (Number, Boolean))
431− , (LessThanOrEqualTo, (Number, Boolean))
432− , (GreaterThan, (Number, Boolean))
433− , (GreaterThanOrEqualTo, (Number, Boolean))
434− ]
435−
436−inferBinder :: Type -> Binder -> Subst (M.Map Ident Type)
437−inferBinder _ NullBinder = return M.empty
438−inferBinder val (StringBinder _) = val ~~ String >> return M.empty
439−inferBinder val (NumberBinder _) = val ~~ Number >> return M.empty
440−inferBinder val (BooleanBinder _) = val ~~ Boolean >> return M.empty
441−inferBinder val (VarBinder name) = return $ M.singleton name val
442−inferBinder val (NullaryBinder ctor) = do
443− env <- getEnv
444− moduleName <- substCurrentModule <$> ask
445− case M.lookup (qualify moduleName ctor) (dataConstructors env) of
446− Just (ty, _) -> do
447− ty `subsumes` val
448− return M.empty
449− _ -> throwError $ "Constructor " ++ show ctor ++ " is not defined"
450−inferBinder val (UnaryBinder ctor binder) = do
451− env <- getEnv
452− moduleName <- substCurrentModule <$> ask
453− case M.lookup (qualify moduleName ctor) (dataConstructors env) of
454− Just (ty, _) -> do
455− fn <- replaceAllVarsWithUnknowns ty
456− case fn of
457− Function [obj] ret -> do
458− val `subsumes` ret
459− inferBinder obj binder
460− _ -> throwError $ "Constructor " ++ show ctor ++ " is not a unary constructor"
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 :: Type -> Type -> [(String, Binder)] -> Subst (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) = do
477− el <- fresh
478− m1 <- M.unions <$> mapM (inferBinder el) binders
479− val ~~ Array el
480− return m1
481−inferBinder val (ConsBinder headBinder tailBinder) = do
482− el <- fresh
483− m1 <- inferBinder el headBinder
484− m2 <- inferBinder val tailBinder
485− val ~~ Array el
486− return $ m1 `M.union` m2
487−inferBinder val (NamedBinder name binder) = do
488− m <- inferBinder val binder
489− return $ M.insert name val m
490−
491−checkBinders :: [Type] -> Type -> [([Binder], Maybe Guard, Value)] -> Subst [([Binder], Maybe Guard, Value)]
492−checkBinders _ _ [] = return []
493−checkBinders nvals ret ((binders, grd, val):bs) = do
494− moduleName <- substCurrentModule <$> ask
495− m1 <- M.unions <$> zipWithM inferBinder nvals binders
496− r <- bindLocalVariables moduleName (M.toList m1) $ do
497− val' <- check val ret
498− case grd of
499− Nothing -> return (binders, Nothing, val')
500− Just g -> do
501− g' <- check g Boolean
502− return (binders, Just g', val')
503− rs <- checkBinders nvals ret bs
504− return $ r : rs
505−
506−assignVariable :: Ident -> Subst ()
507−assignVariable name = do
508− env <- checkEnv <$> get
509− moduleName <- substCurrentModule <$> ask
510− case M.lookup (moduleName, name) (names env) of
511− Just (_, LocalVariable) -> throwError $ "Variable with name " ++ show name ++ " already exists."
512− _ -> return ()
513−
514−checkStatement :: M.Map Ident Type -> Type -> Statement -> Subst (Bool, M.Map Ident Type, Statement)
515−checkStatement mass _ (VariableIntroduction name val) = do
516− assignVariable name
517− val'@(TypedValue _ t) <- infer val
518− return (False, M.insert name t mass, VariableIntroduction name val')
519−checkStatement mass _ (Assignment ident val) = do
520− val'@(TypedValue _ t) <- infer val
521− case M.lookup ident mass of
522− Nothing -> throwError $ "No local variable with name " ++ show ident
523− Just ty -> do t ~~ ty
524− return (False, mass, Assignment ident val')
525−checkStatement mass ret (While val inner) = do
526− val' <- check val Boolean
527− (allCodePathsReturn, _, inner') <- checkBlock mass ret inner
528− return (allCodePathsReturn, mass, While val' inner')
529−checkStatement mass ret (If ifst) = do
530− (allCodePathsReturn, ifst') <- checkIfStatement mass ret ifst
531− return (allCodePathsReturn, mass, If ifst')
532−checkStatement mass ret (For ident start end inner) = do
533− moduleName <- substCurrentModule <$> ask
534− assignVariable ident
535− start' <- check start Number
536− end' <- check end Number
537− (allCodePathsReturn, _, inner') <- bindLocalVariables moduleName [(ident, Number)] $ checkBlock mass ret inner
538− return (allCodePathsReturn, mass, For ident start' end' inner')
539−checkStatement mass ret (Return val) = do
540− val' <- check val ret
541− return (True, mass, Return val')
542−
543−checkIfStatement :: M.Map Ident Type -> Type -> IfStatement -> Subst (Bool, IfStatement)
544−checkIfStatement mass ret (IfStatement val thens Nothing) = do
545− val' <- check val Boolean
546− (_, _, thens') <- checkBlock mass ret thens
547− return (False, IfStatement val' thens' Nothing)
548−checkIfStatement mass ret (IfStatement val thens (Just elses)) = do
549− val' <- check val Boolean
550− (allCodePathsReturn1, _, thens') <- checkBlock mass ret thens
551− (allCodePathsReturn2, elses') <- checkElseStatement mass ret elses
552− return (allCodePathsReturn1 && allCodePathsReturn2, IfStatement val' thens' (Just elses'))
553−
554−checkElseStatement :: M.Map Ident Type -> Type -> ElseStatement -> Subst (Bool, ElseStatement)
555−checkElseStatement mass ret (Else elses) = do
556− (allCodePathsReturn, _, elses') <- checkBlock mass ret elses
557− return (allCodePathsReturn, Else elses')
558−checkElseStatement mass ret (ElseIf ifst) = (id *** ElseIf) <$> checkIfStatement mass ret ifst
559−
560−checkBlock :: M.Map Ident Type -> Type -> [Statement] -> Subst (Bool, M.Map Ident Type, [Statement])
561−checkBlock mass _ [] = return (False, mass, [])
562−checkBlock mass ret (s:ss) = do
563− moduleName <- substCurrentModule <$> ask
564− (b1, mass1, s') <- checkStatement mass ret s
565− bindLocalVariables moduleName (M.toList mass1) $ case (b1, ss) of
566− (True, []) -> return (True, mass1, [s'])
567− (True, _) -> throwError "Unreachable code"
568− (False, ss') -> do
569− (b, m, ss'') <- checkBlock mass1 ret ss'
570− return (b, m, s':ss'')
571−
572−skolemize :: String -> Type -> Subst Type
573−skolemize ident ty = do
574− tsk <- Skolem <$> fresh'
575− return $ replaceTypeVars ident tsk ty
576−
577−check :: Value -> Type -> Subst Value
578−check val ty = rethrow errorMessage $ check' val ty
579− where
580− errorMessage msg =
581− "Error checking type of term " ++
582− prettyPrintValue val ++
583− " against type " ++
584− prettyPrintType ty ++
585− ":\n" ++
586− msg
587−
588−check' :: Value -> Type -> Subst Value
589−check' val (ForAll idents ty) = do
590− sk <- skolemize idents ty
591− check val sk
592−check' val u@(TUnknown _) = do
593− val'@(TypedValue _ ty) <- infer val
594− -- Don't unify an unknown with an inferred polytype
595− ty' <- replaceAllVarsWithUnknowns ty
596− ty' ~~ u
597− return val'
598−check' v@(NumericLiteral _) Number = return v
599−check' v@(StringLiteral _) String = return v
600−check' v@(BooleanLiteral _) Boolean = return v
601−check' (Unary op val) ty = checkUnary op val ty
602−check' (Binary op left right) ty = checkBinary op left right ty
603−check' (ArrayLiteral vals) (Array ty) = ArrayLiteral <$> forM vals (\val -> check val ty)
604−check' (Indexer index vals) ty = do
605− index' <- check index Number
606− vals' <- check vals (Array ty)
607− return $ Indexer index' vals'
608−check' (Abs args ret) (Function argTys retTy) = do
609− moduleName <- substCurrentModule <$> ask
610− guardWith "Incorrect number of function arguments" (length args == length argTys)
611− ret' <- bindLocalVariables moduleName (zip args argTys) $ check ret retTy
612− return $ Abs args ret'
613−check' (App f args) ret = do
614− f'@(TypedValue _ ft) <- infer f
615− args' <- checkFunctionApplication ft args ret
616− return $ App f' args'
617−check' (Var var) ty = do
618− moduleName <- substCurrentModule <$> ask
619− ty1 <- lookupVariable moduleName var
620− repl <- replaceAllTypeSynonyms ty1
621− repl `subsumes` ty
622− return $ Var var
623−check' (TypedValue val ty1) ty2 = do
624− moduleName <- substCurrentModule <$> ask
625− kind <- liftCheck $ kindOf moduleName ty1
626− guardWith ("Expected type of kind *, was " ++ prettyPrintKind kind) $ kind == Star
627− ty1 `subsumes` ty2
628− val' <- check val ty1
629− return $ TypedValue val' ty1
630−check' (Case vals binders) ret = do
631− vals' <- mapM infer vals
632− let ts = map (\(TypedValue _ t) -> t) vals'
633− binders' <- checkBinders ts ret binders
634− return $ Case vals' binders'
635−check' (IfThenElse cond th el) ty = do
636− cond' <- check cond Boolean
637− th' <- check th ty
638− el' <- check el ty
639− return $ IfThenElse cond' th' el'
640−check' (ObjectLiteral ps) (Object row) = do
641− ensureNoDuplicateProperties ps
642− ps' <- checkProperties ps row False
643− return $ ObjectLiteral ps'
644−check' (ObjectUpdate obj ps) (Object row) = do
645− ensureNoDuplicateProperties ps
646− us <- zip (map fst ps) <$> replicateM (length ps) fresh
647− let (propsToCheck, rest) = rowToList row
648− propsToRemove = map fst ps
649− remainingProps = filter (\(p, _) -> p `notElem` propsToRemove) propsToCheck
650− obj' <- check obj (Object (rowFromList (us ++ remainingProps, rest)))
651− ps' <- checkProperties ps row True
652− return $ ObjectUpdate obj' ps'
653−check' (Accessor prop val) ty = do
654− rest <- fresh
655− val' <- check val (Object (RCons prop ty rest))
656− return $ Accessor prop val'
657−check' (Block ss) ret = do
658− (allCodePathsReturn, _, ss') <- checkBlock M.empty ret ss
659− guardWith "Block is missing a return statement" allCodePathsReturn
660− return $ Block ss'
661−check' (Constructor c) ty = do
662− env <- getEnv
663− moduleName <- substCurrentModule <$> ask
664− case M.lookup (qualify moduleName c) (dataConstructors env) of
665− Nothing -> throwError $ "Constructor " ++ show c ++ " is undefined"
666− Just (ty1, _) -> do
667− repl <- replaceAllTypeSynonyms ty1
668− repl `subsumes` ty
669− return $ Constructor c
670−check' val (SaturatedTypeSynonym name args) = do
671− ty <- expandTypeSynonym name args
672− check val ty
673−check' val ty = throwError $ prettyPrintValue val ++ " does not have type " ++ prettyPrintType ty
674−
675−checkProperties :: [(String, Value)] -> Type -> Bool -> Subst [(String, Value)]
676−checkProperties ps row lax = let (ts, r') = rowToList row in go ps ts r' where
677− go [] [] REmpty = return []
678− go [] [] u@(TUnknown _) = do u ~~ REmpty
679− return []
680− go [] [] (Skolem _) | lax = return []
681− go [] ((p, _): _) _ | lax = return []
682− | otherwise = throwError $ prettyPrintValue (ObjectLiteral ps) ++ " does not have property " ++ p
683− go ((p,_):_) [] REmpty = throwError $ "Property " ++ p ++ " is not present in closed object type " ++ prettyPrintRow row
684− go ((p,v):ps') [] u@(TUnknown _) = do
685− v'@(TypedValue _ ty) <- infer v
686− rest <- fresh
687− u ~~ RCons p ty rest
688− ps'' <- go ps' [] rest
689− return $ (p, v') : ps''
690− go ((p,v):ps') ts r =
691− case lookup p ts of
692− Nothing -> do
693− v'@(TypedValue _ ty) <- infer v
694− rest <- fresh
695− r ~~ RCons p ty rest
696− ps'' <- go ps' ts rest
697− return $ (p, v') : ps''
698− Just ty -> do
699− v' <- check v ty
700− ps'' <- go ps' (delete (p, ty) ts) r
701− return $ (p, v') : ps''
702− go _ _ _ = throwError $ prettyPrintValue (ObjectLiteral ps) ++ " does not have type " ++ prettyPrintType (Object row)
703−
704−checkFunctionApplication :: Type -> [Value] -> Type -> Subst [Value]
705−checkFunctionApplication fnTy args ret = rethrow errorMessage $ checkFunctionApplication' fnTy args ret
706− where
707− errorMessage msg = "Error applying function of type "
708− ++ prettyPrintType fnTy
709− ++ " to arguments " ++ intercalate ", " (map prettyPrintValue args)
710− ++ ", expecting value of type "
711− ++ prettyPrintType ret ++ ":\n" ++ msg
712−
713−checkFunctionApplication' :: Type -> [Value] -> Type -> Subst [Value]
714−checkFunctionApplication' (Function argTys retTy) args ret = do
715− guardWith "Incorrect number of function arguments" (length args == length argTys)
716− args' <- zipWithM check args argTys
717− retTy `subsumes` ret
718− return args'
719−checkFunctionApplication' (ForAll ident ty) args ret = do
720− replaced <- replaceVarWithUnknown ident ty
721− checkFunctionApplication replaced args ret
722−checkFunctionApplication' u@(TUnknown _) args ret = do
723− args' <- mapM (\arg -> infer arg >>= \(TypedValue v t) -> TypedValue v <$> replaceAllVarsWithUnknowns t) args
724− let tys = map (\(TypedValue _ t) -> t) args'
725− u ~~ Function tys ret
726− return args'
727−checkFunctionApplication' (SaturatedTypeSynonym name tyArgs) args ret = do
728− ty <- expandTypeSynonym name tyArgs
729− checkFunctionApplication' ty args ret
730−checkFunctionApplication' fnTy args ret = throwError $ "Applying a function of type "
731− ++ prettyPrintType fnTy
732− ++ " to argument(s) " ++ intercalate ", " (map prettyPrintValue args)
733− ++ " does not yield a value of type " ++ prettyPrintType ret ++ "."
734−
735−subsumes :: Type -> Type -> Subst ()
736−subsumes (ForAll ident ty1) ty2 = do
737− replaced <- replaceVarWithUnknown ident ty1
738− replaced `subsumes` ty2
739−subsumes (Function args1 ret1) (Function args2 ret2) = do
740− zipWithM_ subsumes args2 args1
741− ret1 `subsumes` ret2
742−subsumes ty1 ty2 = ty1 ~~ ty2
743−