@@ -1,807 +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 (maybeToList, isNothing, isJust, fromMaybe)
24−import qualified Data.Data as D
25−import Data.Generics
26− (mkM, everywhereM, everything, mkT, something, everywhere, mkQ)
27−
28−import Language.PureScript.Values
29−import Language.PureScript.Types
30−import Language.PureScript.Kinds
31−import Language.PureScript.Names
32−import Language.PureScript.TypeChecker.Monad
33−import Language.PureScript.TypeChecker.Kinds
34−import Language.PureScript.TypeChecker.Synonyms
35−import Language.PureScript.Pretty
36−import Language.PureScript.Unknown
37−
38−import Control.Monad.State
39−import Control.Monad.Error
40−import Control.Monad.Reader
41−
42−import Control.Applicative
43−import Control.Arrow (Arrow(..))
44−
45−import qualified Data.Map as M
46−import Data.Function (on)
47−
48−instance Unifiable Type where
49− unknown = TUnknown
50− isUnknown (TUnknown u) = Just u
51− isUnknown _ = Nothing
52− (~~) = unifyTypes
53− apply s (TUnknown u) = runSubstitution s u
54− apply s (SaturatedTypeSynonym name tys) = SaturatedTypeSynonym name $ map (apply s) tys
55− apply s (ForAll idents ty) = ForAll idents $ apply s ty
56− apply s (Array t) = Array (apply s t)
57− apply s (Object r) = Object (apply s r)
58− apply s (Function args ret) = Function (map (apply s) args) (apply s ret)
59− apply s (TypeApp t1 t2) = TypeApp (apply s t1) (apply s t2)
60− apply s (RCons name ty r) = RCons name (apply s ty) (apply s r)
61− apply _ t = t
62− unknowns (TUnknown (Unknown u)) = [u]
63− unknowns (SaturatedTypeSynonym _ tys) = concatMap unknowns tys
64− unknowns (ForAll _ ty) = unknowns ty
65− unknowns (Array t) = unknowns t
66− unknowns (Object r) = unknowns r
67− unknowns (Function args ret) = concatMap unknowns args ++ unknowns ret
68− unknowns (TypeApp t1 t2) = unknowns t1 ++ unknowns t2
69− unknowns (RCons _ ty r) = unknowns ty ++ unknowns r
70− unknowns _ = []
71−
72−unifyTypes :: Type -> Type -> Subst ()
73−unifyTypes t1 t2 = rethrow (\e -> "Error unifying type " ++ prettyPrintType t1 ++ " with type " ++ prettyPrintType t2 ++ ":\n" ++ e) $ do
74− unifyTypes' t1 t2
75− where
76− unifyTypes' (TUnknown u1) (TUnknown u2) | u1 == u2 = return ()
77− unifyTypes' (TUnknown u) t = replace u t
78− unifyTypes' t (TUnknown u) = replace u t
79− unifyTypes' (SaturatedTypeSynonym name args) ty = do
80− ty1 <- expandTypeSynonym name args
81− ty1 `unifyTypes` ty
82− unifyTypes' ty s@(SaturatedTypeSynonym _ _) = s `unifyTypes` ty
83− unifyTypes' (ForAll ident1 ty1) (ForAll ident2 ty2) = do
84− sk <- skolemize ident1 ty1
85− replaced <- replaceVarWithUnknown ident2 ty2
86− sk `unifyTypes` replaced
87− unifyTypes' (ForAll ident ty1) ty2 = do
88− sk <- skolemize ident ty1
89− sk `unifyTypes` ty2
90− unifyTypes' ty f@(ForAll _ _) = f `unifyTypes` ty
91− unifyTypes' Number Number = return ()
92− unifyTypes' String String = return ()
93− unifyTypes' Boolean Boolean = return ()
94− unifyTypes' (Array s) (Array t) = s `unifyTypes` t
95− unifyTypes' (Object row1) (Object row2) = row1 ~~ row2
96− unifyTypes' (Function args1 ret1) (Function args2 ret2) = do
97− guardWith "Function applied to incorrect number of args" $ length args1 == length args2
98− zipWithM_ unifyTypes args1 args2
99− ret1 `unifyTypes` ret2
100− unifyTypes' (TypeVar v1) (TypeVar v2) | v1 == v2 = return ()
101− unifyTypes' (TypeConstructor c1) (TypeConstructor c2) = do
102− env <- getEnv
103− moduleName <- substCurrentModule `fmap` ask
104− guardWith ("Cannot unify " ++ show c1 ++ " with " ++ show c2 ++ ".") (typeConstructorsAreEqual env moduleName c1 c2)
105− unifyTypes' (TypeApp t3 t4) (TypeApp t5 t6) = do
106− t3 `unifyTypes` t5
107− t4 `unifyTypes` t6
108− unifyTypes' (Skolem s1) (Skolem s2) | s1 == s2 = return ()
109− unifyTypes' r1@(RCons _ _ _) r2 = unifyRows r1 r2
110− unifyTypes' r1 r2@(RCons _ _ _) = unifyRows r1 r2
111− unifyTypes' r1@REmpty r2 = unifyRows r1 r2
112− unifyTypes' r1 r2@REmpty = unifyRows r1 r2
113− unifyTypes' t3 t4 = throwError $ "Cannot unify " ++ prettyPrintType t3 ++ " with " ++ prettyPrintType t4 ++ "."
114−
115−unifyRows :: Type -> Type -> Subst ()
116−unifyRows r1 r2 =
117− let
118− (s1, r1') = rowToList r1
119− (s2, r2') = rowToList r2
120− int = [ (t1, t2) | (name, t1) <- s1, (name', t2) <- s2, name == name' ]
121− sd1 = [ (name, t1) | (name, t1) <- s1, name `notElem` map fst s2 ]
122− sd2 = [ (name, t2) | (name, t2) <- s2, name `notElem` map fst s1 ]
123− in do
124− forM_ int (uncurry (~~))
125− unifyRows' sd1 r1' sd2 r2'
126− where
127− unifyRows' :: [(String, Type)] -> Type -> [(String, Type)] -> Type -> Subst ()
128− unifyRows' [] (TUnknown u) sd r = replace u (rowFromList (sd, r))
129− unifyRows' sd r [] (TUnknown u) = replace u (rowFromList (sd, r))
130− unifyRows' ((name, ty):row) r others u@(TUnknown un) = do
131− occursCheck un ty
132− forM_ row $ \(_, t) -> occursCheck un t
133− u' <- fresh
134− u ~~ RCons name ty u'
135− unifyRows' row r others u'
136− unifyRows' [] REmpty [] REmpty = return ()
137− unifyRows' [] (TypeVar v1) [] (TypeVar v2) | v1 == v2 = return ()
138− unifyRows' [] (Skolem s1) [] (Skolem s2) | s1 == s2 = return ()
139− unifyRows' sd3 r3 sd4 r4 = throwError $ "Cannot unify " ++ prettyPrintRow (rowFromList (sd3, r3)) ++ " with " ++ prettyPrintRow (rowFromList (sd4, r4)) ++ "."
140−
141−typeConstructorsAreEqual :: Environment -> ModuleName -> Qualified ProperName -> Qualified ProperName -> Bool
142−typeConstructorsAreEqual env moduleName = (==) `on` canonicalizeType moduleName env
143−
144−typesOf :: ModuleName -> [(Ident, Value)] -> Check [(Ident, (Value, Type))]
145−typesOf moduleName vals = do
146− tys <- fmap (\(tys, s) -> map (\(ident, (val, ty)) -> (ident, (overTypes (apply s) val, apply s ty))) tys)
147− . runSubst (SubstContext moduleName) $ do
148− let es = map isTyped vals
149− typed = filter (isJust . snd . snd) es
150− untyped = filter (isNothing . snd . snd) es
151− typedDict = map (\(ident, (_, Just ty)) -> (ident, ty)) typed
152− untypedNames <- replicateM (length untyped) fresh
153− let untypedDict = zip (map fst untyped) untypedNames
154− dict = M.fromList (map (\(ident, ty) -> ((moduleName, ident), (ty, LocalVariable))) $ (map (id *** fst) typedDict) ++ untypedDict)
155− forM es $ \e -> do
156− triple@(_, (val, ty)) <- case e of
157− (ident, (val, Just (ty, checkType))) -> do
158− kind <- liftCheck $ kindOf moduleName ty
159− guardWith ("Expected type of kind *, was " ++ prettyPrintKind kind) $ kind == Star
160− ty' <- replaceAllTypeSynonyms ty
161− val' <- bindNames dict $ if checkType then check val ty' else return val
162− return (ident, (val', ty'))
163− (ident, (val, Nothing)) -> do
164− TypedValue _ val' ty <- bindNames dict $ infer val
165− ty ~~ fromMaybe (error "name not found in dictionary") (lookup ident untypedDict)
166− return (ident, (val', ty))
167− when (moduleName == ModuleName (ProperName "Main") && fst e == Ident "main") $ do
168− [eff, a] <- replicateM 2 fresh
169− ty ~~ TypeApp (TypeApp (TypeConstructor (Qualified (Just (ModuleName (ProperName "Eff"))) (ProperName "Eff"))) eff) a
170− escapeCheck val ty
171− return triple
172− forM_ tys $ skolemEscapeCheck . snd . snd
173− forM tys $ \(ident, (val, ty)) -> do
174− val' <- replaceTypeClassDictionaries moduleName val
175− return (ident, (overTypes (desaturateAllTypeSynonyms . setifyAll) $ val'
176− , varIfUnknown . desaturateAllTypeSynonyms . setifyAll $ ty))
177−
178−isTyped :: (Ident, Value) -> (Ident, (Value, Maybe (Type, Bool)))
179−isTyped (name, TypedValue checkType value ty) = (name, (value, Just (ty, checkType)))
180−isTyped (name, value) = (name, (value, Nothing))
181−
182−overTypes :: (Type -> Type) -> Value -> Value
183−overTypes f = everywhere (mkT f)
184−
185−replaceTypeClassDictionaries :: ModuleName -> Value -> Check Value
186−replaceTypeClassDictionaries mn = everywhereM (mkM go)
187− where
188− go (TypeClassDictionary constraint dicts) = entails mn dicts constraint
189− go other = return other
190−
191−entails :: ModuleName -> [TypeClassDictionaryInScope] -> (Qualified ProperName, Type) -> Check Value
192−entails moduleName context goal@(className, ty) = do
193− env <- getEnv
194− case go env goal of
195− [] -> throwError $ "No " ++ show className ++ " instance found for " ++ prettyPrintType ty
196− (dict : _) -> return dict
197− where
198− go env (className', ty') =
199− [ mkDictionary (tcdName tcd) args
200− | tcd <- context
201− , qualify moduleName className' == qualify moduleName (tcdClassName tcd)
202− , subst <- maybeToList $ typeHeadsAreEqual moduleName env ty' (tcdInstanceType tcd)
203− , args <- solveSubgoals env subst (tcdDependencies tcd) ]
204− solveSubgoals _ _ Nothing = return Nothing
205− solveSubgoals env subst (Just subgoals) = do
206− dict <- mapM (go env) (replaceAllTypeVars subst subgoals)
207− return $ Just dict
208− mkDictionary fnName Nothing = Var (Qualified Nothing fnName)
209− mkDictionary fnName (Just args) = App (Var (Qualified Nothing fnName)) args
210−
211−typeHeadsAreEqual :: ModuleName -> Environment -> Type -> Type -> Maybe [(String, Type)]
212−typeHeadsAreEqual _ _ String String = Just []
213−typeHeadsAreEqual _ _ Number Number = Just []
214−typeHeadsAreEqual _ _ Boolean Boolean = Just []
215−typeHeadsAreEqual _ _ (Skolem s1) (Skolem s2) | s1 == s2 = Just []
216−typeHeadsAreEqual _ _ (Array (TypeVar v)) (Array ty) = Just [(v, ty)]
217−typeHeadsAreEqual _ _ (Array ty) (Array (TypeVar v)) = Just [(v, ty)]
218−typeHeadsAreEqual m e (Array ty1) (Array ty2) = typeHeadsAreEqual m e ty1 ty2
219−typeHeadsAreEqual m e (TypeConstructor c1) (TypeConstructor c2) | typeConstructorsAreEqual e m c1 c2 = Just []
220−typeHeadsAreEqual m e (TypeApp h1 (TypeVar v)) (TypeApp h2 arg) = (:) (v, arg) <$> typeHeadsAreEqual m e h1 h2
221−typeHeadsAreEqual m e t1@(TypeApp _ _) t2@(TypeApp _ (TypeVar _)) = typeHeadsAreEqual m e t2 t1
222−typeHeadsAreEqual _ _ _ _ = Nothing
223−
224−escapeCheck :: Value -> Type -> Subst ()
225−escapeCheck value ty = do
226− subst <- substSubst <$> getSubstState
227− let visibleUnknowns = nub $ unknowns $ apply subst ty
228− let allUnknowns = findAllTypes value
229− forM_ allUnknowns $ \t -> do
230− let unsolvedUnknowns = nub . unknowns $ apply subst t
231− guardWith "Escape check fails" $ null $ unsolvedUnknowns \\ visibleUnknowns
232−
233−findAllTypes :: Value -> [Type]
234−findAllTypes = everything (++) (mkQ [] go)
235− where
236− go (TypedValue _ _ ty) = [ty]
237− go _ = []
238−
239−skolemEscapeCheck :: Type -> Check ()
240−skolemEscapeCheck ty =
241− case something (mkQ Nothing findSkolems) ty of
242− Nothing -> return ()
243− Just _ -> throwError $ "Skolem variables cannot escape. Consider adding a type signature." ++ show ty
244− where
245− findSkolems (Skolem _) = return ()
246− findSkolems _ = mzero
247−
248−setify :: Type -> Type
249−setify = rowFromList . first (M.toList . M.fromList) . rowToList
250−
251−setifyAll :: (D.Data d) => d -> d
252−setifyAll = everywhere (mkT setify)
253−
254−varIfUnknown :: Type -> Type
255−varIfUnknown ty =
256− let unks = nub $ unknowns ty
257− toName = (:) 't' . show
258− ty' = everywhere (mkT typeToVar) $ ty
259− typeToVar :: Type -> Type
260− typeToVar (TUnknown (Unknown u)) = TypeVar (toName u)
261− typeToVar t = t
262− in mkForAll (sort . map toName $ unks) ty'
263−
264−replaceAllTypeVars :: (D.Data d) => [(String, Type)] -> d -> d
265−replaceAllTypeVars = foldl' (\f (name, ty) -> replaceTypeVars name ty . f) id
266−
267−replaceAllVarsWithUnknowns :: Type -> Subst Type
268−replaceAllVarsWithUnknowns (ForAll ident ty) = replaceVarWithUnknown ident ty >>= replaceAllVarsWithUnknowns
269−replaceAllVarsWithUnknowns ty = return ty
270−
271−replaceVarWithUnknown :: String -> Type -> Subst Type
272−replaceVarWithUnknown ident ty = do
273− tu <- fresh
274− return $ replaceTypeVars ident tu $ ty
275−
276−replaceAllTypeSynonyms :: (Functor m, MonadState CheckState m, MonadReader SubstContext m, MonadError String m) => (D.Data d) => d -> m d
277−replaceAllTypeSynonyms d = do
278− env <- getEnv
279− moduleName <- substCurrentModule <$> ask
280− let syns = map (\((path, name), (args, _)) -> ((path, name), length args)) . M.toList $ typeSynonyms env
281− either throwError return $ saturateAllTypeSynonyms env moduleName syns d
282−
283−desaturateAllTypeSynonyms :: (D.Data d) => d -> d
284−desaturateAllTypeSynonyms = everywhere (mkT replaceSaturatedTypeSynonym)
285− where
286− replaceSaturatedTypeSynonym (SaturatedTypeSynonym name args) = foldl TypeApp (TypeConstructor name) args
287− replaceSaturatedTypeSynonym t = t
288−
289−expandTypeSynonym :: Qualified ProperName -> [Type] -> Subst Type
290−expandTypeSynonym name args = do
291− env <- getEnv
292− moduleName <- substCurrentModule `fmap` ask
293− case M.lookup (canonicalizeType moduleName env name) (typeSynonyms env) of
294− Just (synArgs, body) -> return $ replaceAllTypeVars (zip synArgs args) body
295− Nothing -> error "Type synonym was not defined"
296−
297−ensureNoDuplicateProperties :: (MonadError String m) => [(String, Value)] -> m ()
298−ensureNoDuplicateProperties ps = guardWith "Duplicate property names" $ length (nub . map fst $ ps) == length ps
299−
300−infer :: Value -> Subst Value
301−infer val = rethrow (\e -> "Error inferring type of term " ++ prettyPrintValue val ++ ":\n" ++ e) $ infer' val
302−
303−infer' :: Value -> Subst Value
304−infer' v@(NumericLiteral _) = return $ TypedValue True v Number
305−infer' v@(StringLiteral _) = return $ TypedValue True v String
306−infer' v@(BooleanLiteral _) = return $ TypedValue True v Boolean
307−infer' (ArrayLiteral vals) = do
308− ts <- mapM infer vals
309− els <- fresh
310− forM_ ts $ \(TypedValue _ _ t) -> els ~~ Array t
311− return $ TypedValue True (ArrayLiteral ts) els
312−infer' (Unary op val) = do
313− v <- infer val
314− inferUnary op v
315−infer' (Binary op left right) = do
316− v1 <- infer left
317− v2 <- infer right
318− inferBinary op v1 v2
319−infer' (ObjectLiteral ps) = do
320− ensureNoDuplicateProperties ps
321− ts <- mapM (infer . snd) ps
322− let fields = zipWith (\name (TypedValue _ _ t) -> (name, t)) (map fst ps) ts
323− ty = Object $ rowFromList (fields, REmpty)
324− return $ TypedValue True (ObjectLiteral (zip (map fst ps) ts)) ty
325−infer' (ObjectUpdate o ps) = do
326− ensureNoDuplicateProperties ps
327− row <- fresh
328− newVals <- zipWith (\(name, _) t -> (name, t)) ps <$> mapM (infer . snd) ps
329− let newTys = map (\(name, TypedValue _ _ ty) -> (name, ty)) newVals
330− oldTys <- zip (map fst ps) <$> replicateM (length ps) fresh
331− o' <- check o $ Object $ rowFromList (oldTys, row)
332− return $ TypedValue True (ObjectUpdate o' newVals) $ Object $ rowFromList (newTys, row)
333−infer' (Indexer index val) = do
334− el <- fresh
335− index' <- check index Number
336− val' <- check val (Array el)
337− return $ TypedValue True (Indexer (TypedValue True index' Number) (TypedValue True val' (Array el))) el
338−infer' (Accessor prop val) = do
339− typed@(TypedValue _ _ objTy) <- infer val
340− propTy <- inferProperty objTy prop
341− case propTy of
342− Nothing -> do
343− field <- fresh
344− rest <- fresh
345− objTy `subsumes` Object (RCons prop field rest)
346− return $ TypedValue True (Accessor prop typed) field
347− Just ty -> return $ TypedValue True (Accessor prop typed) ty
348−infer' (Abs args ret) = do
349− ts <- replicateM (length args) fresh
350− moduleName <- substCurrentModule <$> ask
351− bindLocalVariables moduleName (zip args ts) $ do
352− body@(TypedValue _ _ bodyTy) <- infer' ret
353− return $ TypedValue True (Abs args body) $ Function ts bodyTy
354−infer' (App f args) = do
355− f'@(TypedValue _ _ ft) <- infer f
356− ret <- fresh
357− app <- checkFunctionApplication f' ft args ret
358− return $ TypedValue True app ret
359−infer' (Var var) = do
360− moduleName <- substCurrentModule <$> ask
361− ty <- lookupVariable moduleName var
362− ty' <- replaceAllTypeSynonyms ty
363− case ty' of
364− ConstrainedType constraints _ -> do
365− env <- getEnv
366− dicts <- getTypeClassDictionaries
367− return $ TypedValue True (App (Var var) (map (flip TypeClassDictionary dicts) (qualifyAllUnqualifiedNames moduleName env constraints))) ty'
368− _ -> return $ TypedValue True (Var var) ty'
369−infer' (Block ss) = do
370− ret <- fresh
371− (allCodePathsReturn, _, ss') <- checkBlock M.empty ret ss
372− guardWith "Block is missing a return statement" allCodePathsReturn
373− return $ TypedValue True (Block ss') ret
374−infer' v@(Constructor c) = do
375− env <- getEnv
376− moduleName <- substCurrentModule `fmap` ask
377− case M.lookup (qualify moduleName c) (dataConstructors env) of
378− Nothing -> throwError $ "Constructor " ++ show c ++ " is undefined"
379− Just (ty, _) -> do ty' <- replaceAllTypeSynonyms ty
380− return $ TypedValue True v ty'
381−infer' (Case vals binders) = do
382− ts <- mapM infer vals
383− ret <- fresh
384− binders' <- checkBinders (map (\(TypedValue _ _ t) -> t) ts) ret binders
385− return $ TypedValue True (Case ts binders') ret
386−infer' (IfThenElse cond th el) = do
387− cond' <- check cond Boolean
388− v2@(TypedValue _ _ t2) <- infer th
389− v3@(TypedValue _ _ t3) <- infer el
390− t2 ~~ t3
391− return $ TypedValue True (IfThenElse cond' v2 v3) t2
392−infer' (TypedValue checkType val ty) = do
393− moduleName <- substCurrentModule <$> ask
394− kind <- liftCheck $ kindOf moduleName ty
395− guardWith ("Expected type of kind *, was " ++ prettyPrintKind kind) $ kind == Star
396− ty' <- replaceAllTypeSynonyms ty
397− val' <- if checkType then check val ty' else return val
398− return $ TypedValue True val' ty
399−infer' _ = error "Invalid argument to infer"
400−
401−inferProperty :: Type -> String -> Subst (Maybe Type)
402−inferProperty (Object row) prop = do
403− let (props, _) = rowToList row
404− return $ lookup prop props
405−inferProperty (SaturatedTypeSynonym name args) prop = do
406− replaced <- expandTypeSynonym name args
407− inferProperty replaced prop
408−inferProperty (ForAll ident ty) prop = do
409− replaced <- replaceVarWithUnknown ident ty
410− inferProperty replaced prop
411−inferProperty _ _ = return Nothing
412−
413−inferUnary :: UnaryOperator -> Value -> Subst Value
414−inferUnary op (TypedValue _ val valTy) =
415− case fromMaybe (error "Invalid operator") $ lookup op unaryOps of
416− (valTy', resTy) -> do
417− valTy' ~~ valTy
418− return $ TypedValue True (Unary op val) resTy
419−inferUnary _ _ = error "Invalid arguments to inferUnary"
420−
421−checkUnary :: UnaryOperator -> Value -> Type -> Subst Value
422−checkUnary op val res =
423− case fromMaybe (error "Invalid operator") $ lookup op unaryOps of
424− (valTy, resTy) -> do
425− res ~~ resTy
426− val' <- check val valTy
427− return $ Unary op val'
428−
429−unaryOps :: [(UnaryOperator, (Type, Type))]
430−unaryOps = [ (Negate, (Number, Number))
431− , (Not, (Boolean, Boolean))
432− , (BitwiseNot, (Number, Number))
433− ]
434−
435−inferBinary :: BinaryOperator -> Value -> Value -> Subst Value
436−inferBinary op left@(TypedValue _ _ leftTy) right@(TypedValue _ _ rightTy) | isEqualityTest op = do
437− leftTy ~~ rightTy
438− return $ TypedValue True (Binary op left right) Boolean
439−inferBinary op left@(TypedValue _ _ leftTy) right@(TypedValue _ _ rightTy) =
440− case fromMaybe (error "Invalid operator") $ lookup op binaryOps of
441− (valTy, resTy) -> do
442− leftTy ~~ valTy
443− rightTy ~~ valTy
444− return $ TypedValue True (Binary op left right) resTy
445−inferBinary _ _ _ = error "Invalid arguments to inferBinary"
446−
447−checkBinary :: BinaryOperator -> Value -> Value -> Type -> Subst Value
448−checkBinary op left right res | isEqualityTest op = do
449− res ~~ Boolean
450− left'@(TypedValue _ _ t1) <- infer left
451− right'@(TypedValue _ _ t2) <- infer right
452− t1 ~~ t2
453− return $ Binary op left' right'
454−checkBinary op left right res =
455− case fromMaybe (error "Invalid operator") $ lookup op binaryOps of
456− (valTy, resTy) -> do
457− res ~~ resTy
458− left' <- check left valTy
459− right' <- check right valTy
460− return $ Binary op left' right'
461−
462−isEqualityTest :: BinaryOperator -> Bool
463−isEqualityTest EqualTo = True
464−isEqualityTest NotEqualTo = True
465−isEqualityTest _ = False
466−
467−binaryOps :: [(BinaryOperator, (Type, Type))]
468−binaryOps = [ (Add, (Number, Number))
469− , (Subtract, (Number, Number))
470− , (Multiply, (Number, Number))
471− , (Divide, (Number, Number))
472− , (Modulus, (Number, Number))
473− , (BitwiseAnd, (Number, Number))
474− , (BitwiseOr, (Number, Number))
475− , (BitwiseXor, (Number, Number))
476− , (ShiftRight, (Number, Number))
477− , (ZeroFillShiftRight, (Number, Number))
478− , (And, (Boolean, Boolean))
479− , (Or, (Boolean, Boolean))
480− , (Concat, (String, String))
481− , (Modulus, (Number, Number))
482− , (LessThan, (Number, Boolean))
483− , (LessThanOrEqualTo, (Number, Boolean))
484− , (GreaterThan, (Number, Boolean))
485− , (GreaterThanOrEqualTo, (Number, Boolean))
486− ]
487−
488−inferBinder :: Type -> Binder -> Subst (M.Map Ident Type)
489−inferBinder _ NullBinder = return M.empty
490−inferBinder val (StringBinder _) = val ~~ String >> return M.empty
491−inferBinder val (NumberBinder _) = val ~~ Number >> return M.empty
492−inferBinder val (BooleanBinder _) = val ~~ Boolean >> return M.empty
493−inferBinder val (VarBinder name) = return $ M.singleton name val
494−inferBinder val (NullaryBinder ctor) = do
495− env <- getEnv
496− moduleName <- substCurrentModule <$> ask
497− case M.lookup (qualify moduleName ctor) (dataConstructors env) of
498− Just (ty, _) -> do
499− ty `subsumes` val
500− return M.empty
501− _ -> throwError $ "Constructor " ++ show ctor ++ " is not defined"
502−inferBinder val (UnaryBinder ctor binder) = do
503− env <- getEnv
504− moduleName <- substCurrentModule <$> ask
505− case M.lookup (qualify moduleName ctor) (dataConstructors env) of
506− Just (ty, _) -> do
507− fn <- replaceAllVarsWithUnknowns ty
508− case fn of
509− Function [obj] ret -> do
510− val `subsumes` ret
511− inferBinder obj binder
512− _ -> throwError $ "Constructor " ++ show ctor ++ " is not a unary constructor"
513− _ -> throwError $ "Constructor " ++ show ctor ++ " is not defined"
514−inferBinder val (ObjectBinder props) = do
515− row <- fresh
516− rest <- fresh
517− m1 <- inferRowProperties row rest props
518− val ~~ Object row
519− return m1
520− where
521− inferRowProperties :: Type -> Type -> [(String, Binder)] -> Subst (M.Map Ident Type)
522− inferRowProperties nrow row [] = nrow ~~ row >> return M.empty
523− inferRowProperties nrow row ((name, binder):binders) = do
524− propTy <- fresh
525− m1 <- inferBinder propTy binder
526− m2 <- inferRowProperties nrow (RCons name propTy row) binders
527− return $ m1 `M.union` m2
528−inferBinder val (ArrayBinder binders) = do
529− el <- fresh
530− m1 <- M.unions <$> mapM (inferBinder el) binders
531− val ~~ Array el
532− return m1
533−inferBinder val (ConsBinder headBinder tailBinder) = do
534− el <- fresh
535− m1 <- inferBinder el headBinder
536− m2 <- inferBinder val tailBinder
537− val ~~ Array el
538− return $ m1 `M.union` m2
539−inferBinder val (NamedBinder name binder) = do
540− m <- inferBinder val binder
541− return $ M.insert name val m
542−
543−checkBinders :: [Type] -> Type -> [([Binder], Maybe Guard, Value)] -> Subst [([Binder], Maybe Guard, Value)]
544−checkBinders _ _ [] = return []
545−checkBinders nvals ret ((binders, grd, val):bs) = do
546− moduleName <- substCurrentModule <$> ask
547− m1 <- M.unions <$> zipWithM inferBinder nvals binders
548− r <- bindLocalVariables moduleName (M.toList m1) $ do
549− val' <- check val ret
550− case grd of
551− Nothing -> return (binders, Nothing, val')
552− Just g -> do
553− g' <- check g Boolean
554− return (binders, Just g', val')
555− rs <- checkBinders nvals ret bs
556− return $ r : rs
557−
558−assignVariable :: Ident -> Subst ()
559−assignVariable name = do
560− env <- checkEnv <$> get
561− moduleName <- substCurrentModule <$> ask
562− case M.lookup (moduleName, name) (names env) of
563− Just (_, LocalVariable) -> throwError $ "Variable with name " ++ show name ++ " already exists."
564− _ -> return ()
565−
566−checkStatement :: M.Map Ident Type -> Type -> Statement -> Subst (Bool, M.Map Ident Type, Statement)
567−checkStatement mass _ (VariableIntroduction name val) = do
568− assignVariable name
569− val'@(TypedValue _ _ t) <- infer val
570− return (False, M.insert name t mass, VariableIntroduction name val')
571−checkStatement mass _ (Assignment ident val) = do
572− val'@(TypedValue _ _ t) <- infer val
573− case M.lookup ident mass of
574− Nothing -> throwError $ "No local variable with name " ++ show ident
575− Just ty -> do t ~~ ty
576− return (False, mass, Assignment ident val')
577−checkStatement mass ret (While val inner) = do
578− val' <- check val Boolean
579− (allCodePathsReturn, _, inner') <- checkBlock mass ret inner
580− return (allCodePathsReturn, mass, While val' inner')
581−checkStatement mass ret (If ifst) = do
582− (allCodePathsReturn, ifst') <- checkIfStatement mass ret ifst
583− return (allCodePathsReturn, mass, If ifst')
584−checkStatement mass ret (For ident start end inner) = do
585− moduleName <- substCurrentModule <$> ask
586− assignVariable ident
587− start' <- check start Number
588− end' <- check end Number
589− (allCodePathsReturn, _, inner') <- bindLocalVariables moduleName [(ident, Number)] $ checkBlock mass ret inner
590− return (allCodePathsReturn, mass, For ident start' end' inner')
591−checkStatement mass ret (Return val) = do
592− val' <- check val ret
593− return (True, mass, Return val')
594−
595−checkIfStatement :: M.Map Ident Type -> Type -> IfStatement -> Subst (Bool, IfStatement)
596−checkIfStatement mass ret (IfStatement val thens Nothing) = do
597− val' <- check val Boolean
598− (_, _, thens') <- checkBlock mass ret thens
599− return (False, IfStatement val' thens' Nothing)
600−checkIfStatement mass ret (IfStatement val thens (Just elses)) = do
601− val' <- check val Boolean
602− (allCodePathsReturn1, _, thens') <- checkBlock mass ret thens
603− (allCodePathsReturn2, elses') <- checkElseStatement mass ret elses
604− return (allCodePathsReturn1 && allCodePathsReturn2, IfStatement val' thens' (Just elses'))
605−
606−checkElseStatement :: M.Map Ident Type -> Type -> ElseStatement -> Subst (Bool, ElseStatement)
607−checkElseStatement mass ret (Else elses) = do
608− (allCodePathsReturn, _, elses') <- checkBlock mass ret elses
609− return (allCodePathsReturn, Else elses')
610−checkElseStatement mass ret (ElseIf ifst) = (id *** ElseIf) <$> checkIfStatement mass ret ifst
611−
612−checkBlock :: M.Map Ident Type -> Type -> [Statement] -> Subst (Bool, M.Map Ident Type, [Statement])
613−checkBlock mass _ [] = return (False, mass, [])
614−checkBlock mass ret (s:ss) = do
615− moduleName <- substCurrentModule <$> ask
616− (b1, mass1, s') <- checkStatement mass ret s
617− bindLocalVariables moduleName (M.toList mass1) $ case (b1, ss) of
618− (True, []) -> return (True, mass1, [s'])
619− (True, _) -> throwError "Unreachable code"
620− (False, ss') -> do
621− (b, m, ss'') <- checkBlock mass1 ret ss'
622− return (b, m, s':ss'')
623−
624−skolemize :: String -> Type -> Subst Type
625−skolemize ident ty = do
626− tsk <- Skolem <$> fresh'
627− return $ replaceTypeVars ident tsk ty
628−
629−check :: Value -> Type -> Subst Value
630−check val ty = rethrow errorMessage $ check' val ty
631− where
632− errorMessage msg =
633− "Error checking type of term " ++
634− prettyPrintValue val ++
635− " against type " ++
636− prettyPrintType ty ++
637− ":\n" ++
638− msg
639−
640−check' :: Value -> Type -> Subst Value
641−check' val (ForAll idents ty) = do
642− sk <- skolemize idents ty
643− check val sk
644−check' val (ConstrainedType constraints ty) = do
645− env <- getEnv
646− moduleName <- substCurrentModule <$> ask
647− dictNames <- flip mapM constraints $ \(Qualified _ (ProperName className), _) -> do
648− n <- liftCheck freshDictionaryName
649− return $ Ident $ "__dict_" ++ className ++ "_" ++ show n
650− val' <- withTypeClassDictionaries (zipWith (\name (className, instanceTy) -> TypeClassDictionaryInScope name className instanceTy Nothing) dictNames (qualifyAllUnqualifiedNames moduleName env constraints)) $ check val ty
651− return $ Abs dictNames val'
652−check' val u@(TUnknown _) = do
653− val'@(TypedValue _ _ ty) <- infer val
654− -- Don't unify an unknown with an inferred polytype
655− ty' <- replaceAllVarsWithUnknowns ty
656− ty' ~~ u
657− return val'
658−check' v@(NumericLiteral _) Number = return v
659−check' v@(StringLiteral _) String = return v
660−check' v@(BooleanLiteral _) Boolean = return v
661−check' (Unary op val) ty = checkUnary op val ty
662−check' (Binary op left right) ty = checkBinary op left right ty
663−check' (ArrayLiteral vals) (Array ty) = ArrayLiteral <$> forM vals (\val -> check val ty)
664−check' (Indexer index vals) ty = do
665− index' <- check index Number
666− vals' <- check vals (Array ty)
667− return $ Indexer index' vals'
668−check' (Abs args ret) (Function argTys retTy) = do
669− moduleName <- substCurrentModule <$> ask
670− guardWith "Incorrect number of function arguments" (length args == length argTys)
671− ret' <- bindLocalVariables moduleName (zip args argTys) $ check ret retTy
672− return $ Abs args ret'
673−check' (App f args) ret = do
674− f'@(TypedValue _ _ ft) <- infer f
675− app <- checkFunctionApplication f' ft args ret
676− return $ app
677−check' (Var var) ty = do
678− moduleName <- substCurrentModule <$> ask
679− ty1 <- lookupVariable moduleName var
680− repl <- replaceAllTypeSynonyms ty1
681− repl `subsumes` ty
682− return $ Var var
683−check' (TypedValue checkType val ty1) ty2 = do
684− moduleName <- substCurrentModule <$> ask
685− kind <- liftCheck $ kindOf moduleName ty1
686− guardWith ("Expected type of kind *, was " ++ prettyPrintKind kind) $ kind == Star
687− ty1 `subsumes` ty2
688− val' <- if checkType then check val ty1 else return val
689− return $ TypedValue True val' ty1
690−check' (Case vals binders) ret = do
691− vals' <- mapM infer vals
692− let ts = map (\(TypedValue _ _ t) -> t) vals'
693− binders' <- checkBinders ts ret binders
694− return $ Case vals' binders'
695−check' (IfThenElse cond th el) ty = do
696− cond' <- check cond Boolean
697− th' <- check th ty
698− el' <- check el ty
699− return $ IfThenElse cond' th' el'
700−check' (ObjectLiteral ps) (Object row) = do
701− ensureNoDuplicateProperties ps
702− ps' <- checkProperties ps row False
703− return $ ObjectLiteral ps'
704−check' (ObjectUpdate obj ps) (Object row) = do
705− ensureNoDuplicateProperties ps
706− us <- zip (map fst ps) <$> replicateM (length ps) fresh
707− let (propsToCheck, rest) = rowToList row
708− propsToRemove = map fst ps
709− remainingProps = filter (\(p, _) -> p `notElem` propsToRemove) propsToCheck
710− obj' <- check obj (Object (rowFromList (us ++ remainingProps, rest)))
711− ps' <- checkProperties ps row True
712− return $ ObjectUpdate obj' ps'
713−check' (Accessor prop val) ty = do
714− rest <- fresh
715− val' <- check val (Object (RCons prop ty rest))
716− return $ Accessor prop val'
717−check' (Block ss) ret = do
718− (allCodePathsReturn, _, ss') <- checkBlock M.empty ret ss
719− guardWith "Block is missing a return statement" allCodePathsReturn
720− return $ Block ss'
721−check' (Constructor c) ty = do
722− env <- getEnv
723− moduleName <- substCurrentModule <$> ask
724− case M.lookup (qualify moduleName c) (dataConstructors env) of
725− Nothing -> throwError $ "Constructor " ++ show c ++ " is undefined"
726− Just (ty1, _) -> do
727− repl <- replaceAllTypeSynonyms ty1
728− repl `subsumes` ty
729− return $ Constructor c
730−check' val (SaturatedTypeSynonym name args) = do
731− ty <- expandTypeSynonym name args
732− check val ty
733−check' val ty = throwError $ prettyPrintValue val ++ " does not have type " ++ prettyPrintType ty
734−
735−checkProperties :: [(String, Value)] -> Type -> Bool -> Subst [(String, Value)]
736−checkProperties ps row lax = let (ts, r') = rowToList row in go ps ts r' where
737− go [] [] REmpty = return []
738− go [] [] u@(TUnknown _) = do u ~~ REmpty
739− return []
740− go [] [] (Skolem _) | lax = return []
741− go [] ((p, _): _) _ | lax = return []
742− | otherwise = throwError $ prettyPrintValue (ObjectLiteral ps) ++ " does not have property " ++ p
743− go ((p,_):_) [] REmpty = throwError $ "Property " ++ p ++ " is not present in closed object type " ++ prettyPrintRow row
744− go ((p,v):ps') [] u@(TUnknown _) = do
745− v'@(TypedValue _ _ ty) <- infer v
746− rest <- fresh
747− u ~~ RCons p ty rest
748− ps'' <- go ps' [] rest
749− return $ (p, v') : ps''
750− go ((p,v):ps') ts r =
751− case lookup p ts of
752− Nothing -> do
753− v'@(TypedValue _ _ ty) <- infer v
754− rest <- fresh
755− r ~~ RCons p ty rest
756− ps'' <- go ps' ts rest
757− return $ (p, v') : ps''
758− Just ty -> do
759− v' <- check v ty
760− ps'' <- go ps' (delete (p, ty) ts) r
761− return $ (p, v') : ps''
762− go _ _ _ = throwError $ prettyPrintValue (ObjectLiteral ps) ++ " does not have type " ++ prettyPrintType (Object row)
763−
764−checkFunctionApplication :: Value -> Type -> [Value] -> Type -> Subst Value
765−checkFunctionApplication fn fnTy args ret = rethrow errorMessage $ checkFunctionApplication' fn fnTy args ret
766− where
767− errorMessage msg = "Error applying function of type "
768− ++ prettyPrintType fnTy
769− ++ " to arguments " ++ intercalate ", " (map prettyPrintValue args)
770− ++ ":\n" ++ msg
771−
772−checkFunctionApplication' :: Value -> Type -> [Value] -> Type -> Subst Value
773−checkFunctionApplication' fn (Function argTys retTy) args ret = do
774− guardWith "Incorrect number of function arguments" (length args == length argTys)
775− args' <- zipWithM check args argTys
776− retTy `subsumes` ret
777− return $ App fn args'
778−checkFunctionApplication' fn (ForAll ident ty) args ret = do
779− replaced <- replaceVarWithUnknown ident ty
780− checkFunctionApplication fn replaced args ret
781−checkFunctionApplication' fn u@(TUnknown _) args ret = do
782− args' <- mapM (\arg -> infer arg >>= \(TypedValue _ v t) -> TypedValue True v <$> replaceAllVarsWithUnknowns t) args
783− let tys = map (\(TypedValue _ _ t) -> t) args'
784− u ~~ Function tys ret
785− return $ App fn args'
786−checkFunctionApplication' fn (SaturatedTypeSynonym name tyArgs) args ret = do
787− ty <- expandTypeSynonym name tyArgs
788− checkFunctionApplication fn ty args ret
789−checkFunctionApplication' fn (ConstrainedType constraints fnTy) args ret = do
790− env <- getEnv
791− dicts <- getTypeClassDictionaries
792− moduleName <- substCurrentModule <$> ask
793− checkFunctionApplication' (App fn (map (flip TypeClassDictionary dicts) (qualifyAllUnqualifiedNames moduleName env constraints))) fnTy args ret
794−checkFunctionApplication' _ fnTy args ret = throwError $ "Applying a function of type "
795− ++ prettyPrintType fnTy
796− ++ " to argument(s) " ++ intercalate ", " (map prettyPrintValue args)
797− ++ " does not yield a value of type " ++ prettyPrintType ret ++ "."
798−
799−subsumes :: Type -> Type -> Subst ()
800−subsumes (ForAll ident ty1) ty2 = do
801− replaced <- replaceVarWithUnknown ident ty1
802− replaced `subsumes` ty2
803−subsumes (Function args1 ret1) (Function args2 ret2) = do
804− zipWithM_ subsumes args2 args1
805− ret1 `subsumes` ret2
806−subsumes ty1 ty2 = ty1 ~~ ty2
807−