@@ -1,815 +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 (canonicalizeDictionary tcd) args
200− | tcd <- context
201− , filterModule tcd
202− , typeConstructorsAreEqual env moduleName className' (tcdClassName tcd)
203− , subst <- maybeToList $ typeHeadsAreEqual moduleName env ty' (tcdInstanceType tcd)
204− , args <- solveSubgoals env subst (tcdDependencies tcd) ]
205− solveSubgoals _ _ Nothing = return Nothing
206− solveSubgoals env subst (Just subgoals) = do
207− dict <- mapM (go env) (replaceAllTypeVars subst subgoals)
208− return $ Just dict
209− mkDictionary fnName args = maybe id (flip App) args $ (Var fnName)
210− filterModule (TypeClassDictionaryInScope { tcdName = Qualified (Just mn) _ }) | mn == moduleName = True
211− filterModule (TypeClassDictionaryInScope { tcdName = Qualified Nothing _ }) = True
212− filterModule _ = False
213− canonicalizeDictionary (TypeClassDictionaryInScope { tcdType = TCDRegular, tcdName = nm }) = nm
214− canonicalizeDictionary (TypeClassDictionaryInScope { tcdType = TCDAlias nm }) = nm
215−
216−typeHeadsAreEqual :: ModuleName -> Environment -> Type -> Type -> Maybe [(String, Type)]
217−typeHeadsAreEqual _ _ String String = Just []
218−typeHeadsAreEqual _ _ Number Number = Just []
219−typeHeadsAreEqual _ _ Boolean Boolean = Just []
220−typeHeadsAreEqual _ _ (Skolem s1) (Skolem s2) | s1 == s2 = Just []
221−typeHeadsAreEqual _ _ (Array (TypeVar v)) (Array ty) = Just [(v, ty)]
222−typeHeadsAreEqual _ _ (Array ty) (Array (TypeVar v)) = Just [(v, ty)]
223−typeHeadsAreEqual m e (Array ty1) (Array ty2) = typeHeadsAreEqual m e ty1 ty2
224−typeHeadsAreEqual m e (TypeConstructor c1) (TypeConstructor c2) | typeConstructorsAreEqual e m c1 c2 = Just []
225−typeHeadsAreEqual m e (TypeApp h1 (TypeVar v)) (TypeApp h2 arg) = (:) (v, arg) <$> typeHeadsAreEqual m e h1 h2
226−typeHeadsAreEqual m e t1@(TypeApp _ _) t2@(TypeApp _ (TypeVar _)) = typeHeadsAreEqual m e t2 t1
227−typeHeadsAreEqual _ _ _ _ = Nothing
228−
229−escapeCheck :: Value -> Type -> Subst ()
230−escapeCheck value ty = do
231− subst <- substSubst <$> getSubstState
232− let visibleUnknowns = nub $ unknowns $ apply subst ty
233− let allUnknowns = findAllTypes value
234− forM_ allUnknowns $ \t -> do
235− let unsolvedUnknowns = nub . unknowns $ apply subst t
236− guardWith "Escape check fails" $ null $ unsolvedUnknowns \\ visibleUnknowns
237−
238−findAllTypes :: Value -> [Type]
239−findAllTypes = everything (++) (mkQ [] go)
240− where
241− go (TypedValue _ _ ty) = [ty]
242− go _ = []
243−
244−skolemEscapeCheck :: Type -> Check ()
245−skolemEscapeCheck ty =
246− case something (mkQ Nothing findSkolems) ty of
247− Nothing -> return ()
248− Just _ -> throwError $ "Skolem variables cannot escape. Consider adding a type signature." ++ show ty
249− where
250− findSkolems (Skolem _) = return ()
251− findSkolems _ = mzero
252−
253−setify :: Type -> Type
254−setify = rowFromList . first (M.toList . M.fromList) . rowToList
255−
256−setifyAll :: (D.Data d) => d -> d
257−setifyAll = everywhere (mkT setify)
258−
259−varIfUnknown :: Type -> Type
260−varIfUnknown ty =
261− let unks = nub $ unknowns ty
262− toName = (:) 't' . show
263− ty' = everywhere (mkT typeToVar) $ ty
264− typeToVar :: Type -> Type
265− typeToVar (TUnknown (Unknown u)) = TypeVar (toName u)
266− typeToVar t = t
267− in mkForAll (sort . map toName $ unks) ty'
268−
269−replaceAllTypeVars :: (D.Data d) => [(String, Type)] -> d -> d
270−replaceAllTypeVars = foldl' (\f (name, ty) -> replaceTypeVars name ty . f) id
271−
272−replaceAllVarsWithUnknowns :: Type -> Subst Type
273−replaceAllVarsWithUnknowns (ForAll ident ty) = replaceVarWithUnknown ident ty >>= replaceAllVarsWithUnknowns
274−replaceAllVarsWithUnknowns ty = return ty
275−
276−replaceVarWithUnknown :: String -> Type -> Subst Type
277−replaceVarWithUnknown ident ty = do
278− tu <- fresh
279− return $ replaceTypeVars ident tu $ ty
280−
281−replaceAllTypeSynonyms :: (Functor m, MonadState CheckState m, MonadReader SubstContext m, MonadError String m) => (D.Data d) => d -> m d
282−replaceAllTypeSynonyms d = do
283− env <- getEnv
284− moduleName <- substCurrentModule <$> ask
285− let syns = map (\((path, name), (args, _)) -> ((path, name), length args)) . M.toList $ typeSynonyms env
286− either throwError return $ saturateAllTypeSynonyms env moduleName syns d
287−
288−desaturateAllTypeSynonyms :: (D.Data d) => d -> d
289−desaturateAllTypeSynonyms = everywhere (mkT replaceSaturatedTypeSynonym)
290− where
291− replaceSaturatedTypeSynonym (SaturatedTypeSynonym name args) = foldl TypeApp (TypeConstructor name) args
292− replaceSaturatedTypeSynonym t = t
293−
294−expandTypeSynonym :: Qualified ProperName -> [Type] -> Subst Type
295−expandTypeSynonym name args = do
296− env <- getEnv
297− moduleName <- substCurrentModule `fmap` ask
298− case M.lookup (canonicalizeType moduleName env name) (typeSynonyms env) of
299− Just (synArgs, body) -> return $ replaceAllTypeVars (zip synArgs args) body
300− Nothing -> error "Type synonym was not defined"
301−
302−ensureNoDuplicateProperties :: (MonadError String m) => [(String, Value)] -> m ()
303−ensureNoDuplicateProperties ps = guardWith "Duplicate property names" $ length (nub . map fst $ ps) == length ps
304−
305−infer :: Value -> Subst Value
306−infer val = rethrow (\e -> "Error inferring type of term " ++ prettyPrintValue val ++ ":\n" ++ e) $ infer' val
307−
308−infer' :: Value -> Subst Value
309−infer' v@(NumericLiteral _) = return $ TypedValue True v Number
310−infer' v@(StringLiteral _) = return $ TypedValue True v String
311−infer' v@(BooleanLiteral _) = return $ TypedValue True v Boolean
312−infer' (ArrayLiteral vals) = do
313− ts <- mapM infer vals
314− els <- fresh
315− forM_ ts $ \(TypedValue _ _ t) -> els ~~ Array t
316− return $ TypedValue True (ArrayLiteral ts) els
317−infer' (Unary op val) = do
318− v <- infer val
319− inferUnary op v
320−infer' (Binary op left right) = do
321− v1 <- infer left
322− v2 <- infer right
323− inferBinary op v1 v2
324−infer' (ObjectLiteral ps) = do
325− ensureNoDuplicateProperties ps
326− ts <- mapM (infer . snd) ps
327− let fields = zipWith (\name (TypedValue _ _ t) -> (name, t)) (map fst ps) ts
328− ty = Object $ rowFromList (fields, REmpty)
329− return $ TypedValue True (ObjectLiteral (zip (map fst ps) ts)) ty
330−infer' (ObjectUpdate o ps) = do
331− ensureNoDuplicateProperties ps
332− row <- fresh
333− newVals <- zipWith (\(name, _) t -> (name, t)) ps <$> mapM (infer . snd) ps
334− let newTys = map (\(name, TypedValue _ _ ty) -> (name, ty)) newVals
335− oldTys <- zip (map fst ps) <$> replicateM (length ps) fresh
336− o' <- check o $ Object $ rowFromList (oldTys, row)
337− return $ TypedValue True (ObjectUpdate o' newVals) $ Object $ rowFromList (newTys, row)
338−infer' (Indexer index val) = do
339− el <- fresh
340− index' <- check index Number
341− val' <- check val (Array el)
342− return $ TypedValue True (Indexer (TypedValue True index' Number) (TypedValue True val' (Array el))) el
343−infer' (Accessor prop val) = do
344− typed@(TypedValue _ _ objTy) <- infer val
345− propTy <- inferProperty objTy prop
346− case propTy of
347− Nothing -> do
348− field <- fresh
349− rest <- fresh
350− objTy `subsumes` Object (RCons prop field rest)
351− return $ TypedValue True (Accessor prop typed) field
352− Just ty -> return $ TypedValue True (Accessor prop typed) ty
353−infer' (Abs args ret) = do
354− ts <- replicateM (length args) fresh
355− moduleName <- substCurrentModule <$> ask
356− bindLocalVariables moduleName (zip args ts) $ do
357− body@(TypedValue _ _ bodyTy) <- infer' ret
358− return $ TypedValue True (Abs args body) $ Function ts bodyTy
359−infer' (App f args) = do
360− f'@(TypedValue _ _ ft) <- infer f
361− ret <- fresh
362− app <- checkFunctionApplication f' ft args ret
363− return $ TypedValue True app ret
364−infer' (Var var) = do
365− moduleName <- substCurrentModule <$> ask
366− ty <- lookupVariable moduleName var
367− ty' <- replaceAllTypeSynonyms ty
368− case ty' of
369− ConstrainedType constraints _ -> do
370− env <- getEnv
371− dicts <- getTypeClassDictionaries
372− return $ TypedValue True (App (Var var) (map (flip TypeClassDictionary dicts) (qualifyAllUnqualifiedNames moduleName env constraints))) ty'
373− _ -> return $ TypedValue True (Var var) ty'
374−infer' (Block ss) = do
375− ret <- fresh
376− (allCodePathsReturn, _, ss') <- checkBlock M.empty ret ss
377− guardWith "Block is missing a return statement" allCodePathsReturn
378− return $ TypedValue True (Block ss') ret
379−infer' v@(Constructor c) = do
380− env <- getEnv
381− moduleName <- substCurrentModule `fmap` ask
382− case M.lookup (qualify moduleName c) (dataConstructors env) of
383− Nothing -> throwError $ "Constructor " ++ show c ++ " is undefined"
384− Just (ty, _) -> do ty' <- replaceAllTypeSynonyms ty
385− return $ TypedValue True v ty'
386−infer' (Case vals binders) = do
387− ts <- mapM infer vals
388− ret <- fresh
389− binders' <- checkBinders (map (\(TypedValue _ _ t) -> t) ts) ret binders
390− return $ TypedValue True (Case ts binders') ret
391−infer' (IfThenElse cond th el) = do
392− cond' <- check cond Boolean
393− v2@(TypedValue _ _ t2) <- infer th
394− v3@(TypedValue _ _ t3) <- infer el
395− t2 ~~ t3
396− return $ TypedValue True (IfThenElse cond' v2 v3) t2
397−infer' (TypedValue checkType val ty) = do
398− moduleName <- substCurrentModule <$> ask
399− kind <- liftCheck $ kindOf moduleName ty
400− guardWith ("Expected type of kind *, was " ++ prettyPrintKind kind) $ kind == Star
401− ty' <- replaceAllTypeSynonyms ty
402− val' <- if checkType then check val ty' else return val
403− return $ TypedValue True val' ty
404−infer' _ = error "Invalid argument to infer"
405−
406−inferProperty :: Type -> String -> Subst (Maybe Type)
407−inferProperty (Object row) prop = do
408− let (props, _) = rowToList row
409− return $ lookup prop props
410−inferProperty (SaturatedTypeSynonym name args) prop = do
411− replaced <- expandTypeSynonym name args
412− inferProperty replaced prop
413−inferProperty (ForAll ident ty) prop = do
414− replaced <- replaceVarWithUnknown ident ty
415− inferProperty replaced prop
416−inferProperty _ _ = return Nothing
417−
418−inferUnary :: UnaryOperator -> Value -> Subst Value
419−inferUnary op (TypedValue _ val valTy) =
420− case fromMaybe (error "Invalid operator") $ lookup op unaryOps of
421− (valTy', resTy) -> do
422− valTy' ~~ valTy
423− return $ TypedValue True (Unary op val) resTy
424−inferUnary _ _ = error "Invalid arguments to inferUnary"
425−
426−checkUnary :: UnaryOperator -> Value -> Type -> Subst Value
427−checkUnary op val res =
428− case fromMaybe (error "Invalid operator") $ lookup op unaryOps of
429− (valTy, resTy) -> do
430− res ~~ resTy
431− val' <- check val valTy
432− return $ Unary op val'
433−
434−unaryOps :: [(UnaryOperator, (Type, Type))]
435−unaryOps = [ (Negate, (Number, Number))
436− , (Not, (Boolean, Boolean))
437− , (BitwiseNot, (Number, Number))
438− ]
439−
440−inferBinary :: BinaryOperator -> Value -> Value -> Subst Value
441−inferBinary op left@(TypedValue _ _ leftTy) right@(TypedValue _ _ rightTy) | isEqualityTest op = do
442− leftTy ~~ rightTy
443− return $ TypedValue True (Binary op left right) Boolean
444−inferBinary op left@(TypedValue _ _ leftTy) right@(TypedValue _ _ rightTy) =
445− case fromMaybe (error "Invalid operator") $ lookup op binaryOps of
446− (valTy, resTy) -> do
447− leftTy ~~ valTy
448− rightTy ~~ valTy
449− return $ TypedValue True (Binary op left right) resTy
450−inferBinary _ _ _ = error "Invalid arguments to inferBinary"
451−
452−checkBinary :: BinaryOperator -> Value -> Value -> Type -> Subst Value
453−checkBinary op left right res | isEqualityTest op = do
454− res ~~ Boolean
455− left'@(TypedValue _ _ t1) <- infer left
456− right'@(TypedValue _ _ t2) <- infer right
457− t1 ~~ t2
458− return $ Binary op left' right'
459−checkBinary op left right res =
460− case fromMaybe (error "Invalid operator") $ lookup op binaryOps of
461− (valTy, resTy) -> do
462− res ~~ resTy
463− left' <- check left valTy
464− right' <- check right valTy
465− return $ Binary op left' right'
466−
467−isEqualityTest :: BinaryOperator -> Bool
468−isEqualityTest EqualTo = True
469−isEqualityTest NotEqualTo = True
470−isEqualityTest _ = False
471−
472−binaryOps :: [(BinaryOperator, (Type, Type))]
473−binaryOps = [ (Add, (Number, Number))
474− , (Subtract, (Number, Number))
475− , (Multiply, (Number, Number))
476− , (Divide, (Number, Number))
477− , (Modulus, (Number, Number))
478− , (BitwiseAnd, (Number, Number))
479− , (BitwiseOr, (Number, Number))
480− , (BitwiseXor, (Number, Number))
481− , (ShiftRight, (Number, Number))
482− , (ZeroFillShiftRight, (Number, Number))
483− , (And, (Boolean, Boolean))
484− , (Or, (Boolean, Boolean))
485− , (Concat, (String, String))
486− , (Modulus, (Number, Number))
487− , (LessThan, (Number, Boolean))
488− , (LessThanOrEqualTo, (Number, Boolean))
489− , (GreaterThan, (Number, Boolean))
490− , (GreaterThanOrEqualTo, (Number, Boolean))
491− ]
492−
493−inferBinder :: Type -> Binder -> Subst (M.Map Ident Type)
494−inferBinder _ NullBinder = return M.empty
495−inferBinder val (StringBinder _) = val ~~ String >> return M.empty
496−inferBinder val (NumberBinder _) = val ~~ Number >> return M.empty
497−inferBinder val (BooleanBinder _) = val ~~ Boolean >> return M.empty
498−inferBinder val (VarBinder name) = return $ M.singleton name val
499−inferBinder val (NullaryBinder ctor) = do
500− env <- getEnv
501− moduleName <- substCurrentModule <$> ask
502− case M.lookup (qualify moduleName ctor) (dataConstructors env) of
503− Just (ty, _) -> do
504− ty `subsumes` val
505− return M.empty
506− _ -> throwError $ "Constructor " ++ show ctor ++ " is not defined"
507−inferBinder val (UnaryBinder ctor binder) = do
508− env <- getEnv
509− moduleName <- substCurrentModule <$> ask
510− case M.lookup (qualify moduleName ctor) (dataConstructors env) of
511− Just (ty, _) -> do
512− fn <- replaceAllVarsWithUnknowns ty
513− case fn of
514− Function [obj] ret -> do
515− val `subsumes` ret
516− inferBinder obj binder
517− _ -> throwError $ "Constructor " ++ show ctor ++ " is not a unary constructor"
518− _ -> throwError $ "Constructor " ++ show ctor ++ " is not defined"
519−inferBinder val (ObjectBinder props) = do
520− row <- fresh
521− rest <- fresh
522− m1 <- inferRowProperties row rest props
523− val ~~ Object row
524− return m1
525− where
526− inferRowProperties :: Type -> Type -> [(String, Binder)] -> Subst (M.Map Ident Type)
527− inferRowProperties nrow row [] = nrow ~~ row >> return M.empty
528− inferRowProperties nrow row ((name, binder):binders) = do
529− propTy <- fresh
530− m1 <- inferBinder propTy binder
531− m2 <- inferRowProperties nrow (RCons name propTy row) binders
532− return $ m1 `M.union` m2
533−inferBinder val (ArrayBinder binders) = do
534− el <- fresh
535− m1 <- M.unions <$> mapM (inferBinder el) binders
536− val ~~ Array el
537− return m1
538−inferBinder val (ConsBinder headBinder tailBinder) = do
539− el <- fresh
540− m1 <- inferBinder el headBinder
541− m2 <- inferBinder val tailBinder
542− val ~~ Array el
543− return $ m1 `M.union` m2
544−inferBinder val (NamedBinder name binder) = do
545− m <- inferBinder val binder
546− return $ M.insert name val m
547−
548−checkBinders :: [Type] -> Type -> [([Binder], Maybe Guard, Value)] -> Subst [([Binder], Maybe Guard, Value)]
549−checkBinders _ _ [] = return []
550−checkBinders nvals ret ((binders, grd, val):bs) = do
551− moduleName <- substCurrentModule <$> ask
552− m1 <- M.unions <$> zipWithM inferBinder nvals binders
553− r <- bindLocalVariables moduleName (M.toList m1) $ do
554− val' <- check val ret
555− case grd of
556− Nothing -> return (binders, Nothing, val')
557− Just g -> do
558− g' <- check g Boolean
559− return (binders, Just g', val')
560− rs <- checkBinders nvals ret bs
561− return $ r : rs
562−
563−assignVariable :: Ident -> Subst ()
564−assignVariable name = do
565− env <- checkEnv <$> get
566− moduleName <- substCurrentModule <$> ask
567− case M.lookup (moduleName, name) (names env) of
568− Just (_, LocalVariable) -> throwError $ "Variable with name " ++ show name ++ " already exists."
569− _ -> return ()
570−
571−checkStatement :: M.Map Ident Type -> Type -> Statement -> Subst (Bool, M.Map Ident Type, Statement)
572−checkStatement mass _ (VariableIntroduction name val) = do
573− assignVariable name
574− val'@(TypedValue _ _ t) <- infer val
575− return (False, M.insert name t mass, VariableIntroduction name val')
576−checkStatement mass _ (Assignment ident val) = do
577− val'@(TypedValue _ _ t) <- infer val
578− case M.lookup ident mass of
579− Nothing -> throwError $ "No local variable with name " ++ show ident
580− Just ty -> do t ~~ ty
581− return (False, mass, Assignment ident val')
582−checkStatement mass ret (While val inner) = do
583− val' <- check val Boolean
584− (allCodePathsReturn, _, inner') <- checkBlock mass ret inner
585− return (allCodePathsReturn, mass, While val' inner')
586−checkStatement mass ret (If ifst) = do
587− (allCodePathsReturn, ifst') <- checkIfStatement mass ret ifst
588− return (allCodePathsReturn, mass, If ifst')
589−checkStatement mass ret (For ident start end inner) = do
590− moduleName <- substCurrentModule <$> ask
591− assignVariable ident
592− start' <- check start Number
593− end' <- check end Number
594− (allCodePathsReturn, _, inner') <- bindLocalVariables moduleName [(ident, Number)] $ checkBlock mass ret inner
595− return (allCodePathsReturn, mass, For ident start' end' inner')
596−checkStatement mass ret (Return val) = do
597− val' <- check val ret
598− return (True, mass, Return val')
599−
600−checkIfStatement :: M.Map Ident Type -> Type -> IfStatement -> Subst (Bool, IfStatement)
601−checkIfStatement mass ret (IfStatement val thens Nothing) = do
602− val' <- check val Boolean
603− (_, _, thens') <- checkBlock mass ret thens
604− return (False, IfStatement val' thens' Nothing)
605−checkIfStatement mass ret (IfStatement val thens (Just elses)) = do
606− val' <- check val Boolean
607− (allCodePathsReturn1, _, thens') <- checkBlock mass ret thens
608− (allCodePathsReturn2, elses') <- checkElseStatement mass ret elses
609− return (allCodePathsReturn1 && allCodePathsReturn2, IfStatement val' thens' (Just elses'))
610−
611−checkElseStatement :: M.Map Ident Type -> Type -> ElseStatement -> Subst (Bool, ElseStatement)
612−checkElseStatement mass ret (Else elses) = do
613− (allCodePathsReturn, _, elses') <- checkBlock mass ret elses
614− return (allCodePathsReturn, Else elses')
615−checkElseStatement mass ret (ElseIf ifst) = (id *** ElseIf) <$> checkIfStatement mass ret ifst
616−
617−checkBlock :: M.Map Ident Type -> Type -> [Statement] -> Subst (Bool, M.Map Ident Type, [Statement])
618−checkBlock mass _ [] = return (False, mass, [])
619−checkBlock mass ret (s:ss) = do
620− moduleName <- substCurrentModule <$> ask
621− (b1, mass1, s') <- checkStatement mass ret s
622− bindLocalVariables moduleName (M.toList mass1) $ case (b1, ss) of
623− (True, []) -> return (True, mass1, [s'])
624− (True, _) -> throwError "Unreachable code"
625− (False, ss') -> do
626− (b, m, ss'') <- checkBlock mass1 ret ss'
627− return (b, m, s':ss'')
628−
629−skolemize :: String -> Type -> Subst Type
630−skolemize ident ty = do
631− tsk <- Skolem <$> fresh'
632− return $ replaceTypeVars ident tsk ty
633−
634−check :: Value -> Type -> Subst Value
635−check val ty = rethrow errorMessage $ check' val ty
636− where
637− errorMessage msg =
638− "Error checking type of term " ++
639− prettyPrintValue val ++
640− " against type " ++
641− prettyPrintType ty ++
642− ":\n" ++
643− msg
644−
645−check' :: Value -> Type -> Subst Value
646−check' val (ForAll idents ty) = do
647− sk <- skolemize idents ty
648− check val sk
649−check' val (ConstrainedType constraints ty) = do
650− env <- getEnv
651− moduleName <- substCurrentModule <$> ask
652− dictNames <- flip mapM constraints $ \(Qualified _ (ProperName className), _) -> do
653− n <- liftCheck freshDictionaryName
654− return $ Ident $ "__dict_" ++ className ++ "_" ++ show n
655− val' <- withTypeClassDictionaries (zipWith (\name (className, instanceTy) ->
656− TypeClassDictionaryInScope name className instanceTy Nothing TCDRegular) (map (Qualified Nothing) dictNames)
657− (qualifyAllUnqualifiedNames moduleName env constraints)) $
658− check val ty
659− return $ Abs dictNames val'
660−check' val u@(TUnknown _) = do
661− val'@(TypedValue _ _ ty) <- infer val
662− -- Don't unify an unknown with an inferred polytype
663− ty' <- replaceAllVarsWithUnknowns ty
664− ty' ~~ u
665− return val'
666−check' v@(NumericLiteral _) Number = return v
667−check' v@(StringLiteral _) String = return v
668−check' v@(BooleanLiteral _) Boolean = return v
669−check' (Unary op val) ty = checkUnary op val ty
670−check' (Binary op left right) ty = checkBinary op left right ty
671−check' (ArrayLiteral vals) (Array ty) = ArrayLiteral <$> forM vals (\val -> check val ty)
672−check' (Indexer index vals) ty = do
673− index' <- check index Number
674− vals' <- check vals (Array ty)
675− return $ Indexer index' vals'
676−check' (Abs args ret) (Function argTys retTy) = do
677− moduleName <- substCurrentModule <$> ask
678− guardWith "Incorrect number of function arguments" (length args == length argTys)
679− ret' <- bindLocalVariables moduleName (zip args argTys) $ check ret retTy
680− return $ Abs args ret'
681−check' (App f args) ret = do
682− f'@(TypedValue _ _ ft) <- infer f
683− app <- checkFunctionApplication f' ft args ret
684− return $ app
685−check' (Var var) ty = do
686− moduleName <- substCurrentModule <$> ask
687− ty1 <- lookupVariable moduleName var
688− repl <- replaceAllTypeSynonyms ty1
689− repl `subsumes` ty
690− return $ Var var
691−check' (TypedValue checkType val ty1) ty2 = do
692− moduleName <- substCurrentModule <$> ask
693− kind <- liftCheck $ kindOf moduleName ty1
694− guardWith ("Expected type of kind *, was " ++ prettyPrintKind kind) $ kind == Star
695− ty1 `subsumes` ty2
696− val' <- if checkType then check val ty1 else return val
697− return $ TypedValue True val' ty1
698−check' (Case vals binders) ret = do
699− vals' <- mapM infer vals
700− let ts = map (\(TypedValue _ _ t) -> t) vals'
701− binders' <- checkBinders ts ret binders
702− return $ Case vals' binders'
703−check' (IfThenElse cond th el) ty = do
704− cond' <- check cond Boolean
705− th' <- check th ty
706− el' <- check el ty
707− return $ IfThenElse cond' th' el'
708−check' (ObjectLiteral ps) (Object row) = do
709− ensureNoDuplicateProperties ps
710− ps' <- checkProperties ps row False
711− return $ ObjectLiteral ps'
712−check' (ObjectUpdate obj ps) (Object row) = do
713− ensureNoDuplicateProperties ps
714− us <- zip (map fst ps) <$> replicateM (length ps) fresh
715− let (propsToCheck, rest) = rowToList row
716− propsToRemove = map fst ps
717− remainingProps = filter (\(p, _) -> p `notElem` propsToRemove) propsToCheck
718− obj' <- check obj (Object (rowFromList (us ++ remainingProps, rest)))
719− ps' <- checkProperties ps row True
720− return $ ObjectUpdate obj' ps'
721−check' (Accessor prop val) ty = do
722− rest <- fresh
723− val' <- check val (Object (RCons prop ty rest))
724− return $ Accessor prop val'
725−check' (Block ss) ret = do
726− (allCodePathsReturn, _, ss') <- checkBlock M.empty ret ss
727− guardWith "Block is missing a return statement" allCodePathsReturn
728− return $ Block ss'
729−check' (Constructor c) ty = do
730− env <- getEnv
731− moduleName <- substCurrentModule <$> ask
732− case M.lookup (qualify moduleName c) (dataConstructors env) of
733− Nothing -> throwError $ "Constructor " ++ show c ++ " is undefined"
734− Just (ty1, _) -> do
735− repl <- replaceAllTypeSynonyms ty1
736− repl `subsumes` ty
737− return $ Constructor c
738−check' val (SaturatedTypeSynonym name args) = do
739− ty <- expandTypeSynonym name args
740− check val ty
741−check' val ty = throwError $ prettyPrintValue val ++ " does not have type " ++ prettyPrintType ty
742−
743−checkProperties :: [(String, Value)] -> Type -> Bool -> Subst [(String, Value)]
744−checkProperties ps row lax = let (ts, r') = rowToList row in go ps ts r' where
745− go [] [] REmpty = return []
746− go [] [] u@(TUnknown _) = do u ~~ REmpty
747− return []
748− go [] [] (Skolem _) | lax = return []
749− go [] ((p, _): _) _ | lax = return []
750− | otherwise = throwError $ prettyPrintValue (ObjectLiteral ps) ++ " does not have property " ++ p
751− go ((p,_):_) [] REmpty = throwError $ "Property " ++ p ++ " is not present in closed object type " ++ prettyPrintRow row
752− go ((p,v):ps') [] u@(TUnknown _) = do
753− v'@(TypedValue _ _ ty) <- infer v
754− rest <- fresh
755− u ~~ RCons p ty rest
756− ps'' <- go ps' [] rest
757− return $ (p, v') : ps''
758− go ((p,v):ps') ts r =
759− case lookup p ts of
760− Nothing -> do
761− v'@(TypedValue _ _ ty) <- infer v
762− rest <- fresh
763− r ~~ RCons p ty rest
764− ps'' <- go ps' ts rest
765− return $ (p, v') : ps''
766− Just ty -> do
767− v' <- check v ty
768− ps'' <- go ps' (delete (p, ty) ts) r
769− return $ (p, v') : ps''
770− go _ _ _ = throwError $ prettyPrintValue (ObjectLiteral ps) ++ " does not have type " ++ prettyPrintType (Object row)
771−
772−checkFunctionApplication :: Value -> Type -> [Value] -> Type -> Subst Value
773−checkFunctionApplication fn fnTy args ret = rethrow errorMessage $ checkFunctionApplication' fn fnTy args ret
774− where
775− errorMessage msg = "Error applying function of type "
776− ++ prettyPrintType fnTy
777− ++ " to arguments " ++ intercalate ", " (map prettyPrintValue args)
778− ++ ":\n" ++ msg
779−
780−checkFunctionApplication' :: Value -> Type -> [Value] -> Type -> Subst Value
781−checkFunctionApplication' fn (Function argTys retTy) args ret = do
782− guardWith "Incorrect number of function arguments" (length args == length argTys)
783− args' <- zipWithM check args argTys
784− retTy `subsumes` ret
785− return $ App fn args'
786−checkFunctionApplication' fn (ForAll ident ty) args ret = do
787− replaced <- replaceVarWithUnknown ident ty
788− checkFunctionApplication fn replaced args ret
789−checkFunctionApplication' fn u@(TUnknown _) args ret = do
790− args' <- mapM (\arg -> infer arg >>= \(TypedValue _ v t) -> TypedValue True v <$> replaceAllVarsWithUnknowns t) args
791− let tys = map (\(TypedValue _ _ t) -> t) args'
792− u ~~ Function tys ret
793− return $ App fn args'
794−checkFunctionApplication' fn (SaturatedTypeSynonym name tyArgs) args ret = do
795− ty <- expandTypeSynonym name tyArgs
796− checkFunctionApplication fn ty args ret
797−checkFunctionApplication' fn (ConstrainedType constraints fnTy) args ret = do
798− env <- getEnv
799− dicts <- getTypeClassDictionaries
800− moduleName <- substCurrentModule <$> ask
801− checkFunctionApplication' (App fn (map (flip TypeClassDictionary dicts) (qualifyAllUnqualifiedNames moduleName env constraints))) fnTy args ret
802−checkFunctionApplication' _ fnTy args ret = throwError $ "Applying a function of type "
803− ++ prettyPrintType fnTy
804− ++ " to argument(s) " ++ intercalate ", " (map prettyPrintValue args)
805− ++ " does not yield a value of type " ++ prettyPrintType ret ++ "."
806−
807−subsumes :: Type -> Type -> Subst ()
808−subsumes (ForAll ident ty1) ty2 = do
809− replaced <- replaceVarWithUnknown ident ty1
810− replaced `subsumes` ty2
811−subsumes (Function args1 ret1) (Function args2 ret2) = do
812− zipWithM_ subsumes args2 args1
813− ret1 `subsumes` ret2
814−subsumes ty1 ty2 = ty1 ~~ ty2
815−