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