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