@@ -1,799 +0,0 @@
1−-----------------------------------------------------------------------------
3−-- Module : Language.PureScript.TypeChecker.Types
4−-- Copyright : (c) Phil Freeman 2013
7−-- Maintainer : Phil Freeman <paf31@cantab.net>
8−-- Stability : experimental
13−-----------------------------------------------------------------------------
15−{-# OPTIONS_GHC -fno-warn-orphans #-}
16−{-# LANGUAGE DeriveDataTypeable, FlexibleContexts #-}
18−module Language.PureScript.TypeChecker.Types (
23−import Data.Maybe (maybeToList, isNothing, isJust, fromMaybe)
24−import qualified Data.Data as D
26− (mkM, everywhereM, everything, mkT, something, everywhere, mkQ)
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
38−import Control.Monad.State
39−import Control.Monad.Error
40−import Control.Monad.Reader
42−import Control.Applicative
43−import Control.Arrow (Arrow(..))
45−import qualified Data.Map as M
46−import Data.Function (on)
48−instance Unifiable Type where
50− isUnknown (TUnknown u) = Just u
51− isUnknown _ = Nothing
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)
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
72−unifyTypes :: Type -> Type -> Subst ()
73−unifyTypes t1 t2 = rethrow (\e -> "Error unifying type " ++ prettyPrintType t1 ++ " with type " ++ prettyPrintType t2 ++ ":\n" ++ e) $ do
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
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
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
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
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 ++ "."
115−unifyRows :: Type -> Type -> Subst ()
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 ]
124− forM_ int (uncurry (~~))
125− unifyRows' sd1 r1' sd2 r2'
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
132− forM_ row $ \(_, t) -> occursCheck un t
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)) ++ "."
141−typeConstructorsAreEqual :: Environment -> ModuleName -> Qualified ProperName -> Qualified ProperName -> Bool
142−typeConstructorsAreEqual env moduleName = (==) `on` canonicalizeType moduleName env
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)
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
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))
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))
182−overTypes :: (Type -> Type) -> Value -> Value
183−overTypes f = everywhere (mkT f)
185−replaceTypeClassDictionaries :: ModuleName -> Value -> Check Value
186−replaceTypeClassDictionaries mn = everywhereM (mkM go)
188− go (TypeClassDictionary constraint dicts) = entails mn dicts constraint
189− go other = return other
191−entails :: ModuleName -> [(Ident, [(Qualified ProperName, Type)], Qualified ProperName, Type)] -> (Qualified ProperName, Type) -> Check Value
192−entails moduleName context goal@(className, ty) = do
195− [] -> throwError $ "No " ++ show className ++ " instance found for " ++ prettyPrintType ty
196− (dict : _) -> return dict
198− go env (className', ty') =
199− [ App (Var (Qualified Nothing fnName)) args
200− | (fnName, subgoals, className'', ty'') <- context
201− , qualify moduleName className' == qualify moduleName className''
202− , subst <- maybeToList $ typeHeadsAreEqual moduleName env ty' ty''
203− , args <- forM (replaceAllTypeVars subst subgoals) (go env) ]
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) <$> typeHeadsAreEqual m e h1 h2
213−typeHeadsAreEqual m e t1@(TypeApp _ _) t2@(TypeApp _ (TypeVar _)) = typeHeadsAreEqual m e t2 t1
214−typeHeadsAreEqual _ _ _ _ = Nothing
216−escapeCheck :: Value -> Type -> Subst ()
217−escapeCheck value ty = do
218− subst <- substSubst <$> 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
225−findAllTypes :: Value -> [Type]
226−findAllTypes = everything (++) (mkQ [] go)
228− go (TypedValue _ ty) = [ty]
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
237− findSkolems (Skolem _) = return ()
238− findSkolems _ = mzero
240−setify :: Type -> Type
241−setify = rowFromList . first (M.toList . M.fromList) . rowToList
243−setifyAll :: (D.Data d) => d -> d
244−setifyAll = everywhere (mkT setify)
246−varIfUnknown :: Type -> Type
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)
254− in mkForAll (sort . map toName $ unks) ty'
256−replaceAllTypeVars :: (D.Data d) => [(String, Type)] -> d -> d
257−replaceAllTypeVars = foldl' (\f (name, ty) -> replaceTypeVars name ty . f) id
259−replaceAllVarsWithUnknowns :: Type -> Subst Type
260−replaceAllVarsWithUnknowns (ForAll ident ty) = replaceVarWithUnknown ident ty >>= replaceAllVarsWithUnknowns
261−replaceAllVarsWithUnknowns ty = return ty
263−replaceVarWithUnknown :: String -> Type -> Subst Type
264−replaceVarWithUnknown ident ty = do
266− return $ replaceTypeVars ident tu $ ty
268−replaceAllTypeSynonyms :: (Functor m, MonadState CheckState m, MonadReader SubstContext m, MonadError String m) => (D.Data d) => d -> m d
269−replaceAllTypeSynonyms d = do
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
275−desaturateAllTypeSynonyms :: (D.Data d) => d -> d
276−desaturateAllTypeSynonyms = everywhere (mkT replaceSaturatedTypeSynonym)
278− replaceSaturatedTypeSynonym (SaturatedTypeSynonym name args) = foldl TypeApp (TypeConstructor name) args
279− replaceSaturatedTypeSynonym t = t
281−expandTypeSynonym :: Qualified ProperName -> [Type] -> Subst Type
282−expandTypeSynonym name args = do
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"
289−ensureNoDuplicateProperties :: (MonadError String m) => [(String, Value)] -> m ()
290−ensureNoDuplicateProperties ps = guardWith "Duplicate property names" $ length (nub . map fst $ ps) == length ps
292−infer :: Value -> Subst Value
293−infer val = rethrow (\e -> "Error inferring type of term " ++ prettyPrintValue val ++ ":\n" ++ e) $ infer' val
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
302− forM_ ts $ \(TypedValue _ t) -> els ~~ Array t
303− return $ TypedValue (ArrayLiteral ts) els
304−infer' (Unary op val) = do
307−infer' (Binary op left right) = do
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
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
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
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
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
356− ConstrainedType constraints _ -> do
358− dicts <- getTypeClassDictionaries
359− return $ TypedValue (App (Var var) (map (flip TypeClassDictionary dicts) (qualifyAllUnqualifiedNames moduleName env constraints))) ty'
360− _ -> return $ TypedValue (Var var) ty'
361−infer' (Block ss) = do
363− (allCodePathsReturn, _, ss') <- checkBlock M.empty ret ss
364− guardWith "Block is missing a return statement" allCodePathsReturn
365− return $ TypedValue (Block ss') ret
366−infer' v@(Constructor c) = do
368− moduleName <- substCurrentModule `fmap` ask
369− case M.lookup (qualify moduleName c) (dataConstructors env) of
370− Nothing -> throwError $ "Constructor " ++ show c ++ " is undefined"
371− Just (ty, _) -> do ty' <- replaceAllTypeSynonyms ty
372− return $ TypedValue v ty'
373−infer' (Case vals binders) = do
374− ts <- mapM infer vals
376− binders' <- checkBinders (map (\(TypedValue _ t) -> t) ts) ret binders
377− return $ TypedValue (Case ts binders') ret
378−infer' (IfThenElse cond th el) = do
379− cond' <- check cond Boolean
380− v2@(TypedValue _ t2) <- infer th
381− v3@(TypedValue _ t3) <- infer el
383− return $ TypedValue (IfThenElse cond' v2 v3) t2
384−infer' (TypedValue val ty) = do
385− moduleName <- substCurrentModule <$> ask
386− kind <- liftCheck $ kindOf moduleName ty
387− guardWith ("Expected type of kind *, was " ++ prettyPrintKind kind) $ kind == Star
388− ty' <- replaceAllTypeSynonyms ty
389− val' <- check val ty'
390− return $ TypedValue val' ty
391−infer' _ = error "Invalid argument to infer"
393−inferProperty :: Type -> String -> Subst (Maybe Type)
394−inferProperty (Object row) prop = do
395− let (props, _) = rowToList row
396− return $ lookup prop props
397−inferProperty (SaturatedTypeSynonym name args) prop = do
398− replaced <- expandTypeSynonym name args
399− inferProperty replaced prop
400−inferProperty (ForAll ident ty) prop = do
401− replaced <- replaceVarWithUnknown ident ty
402− inferProperty replaced prop
403−inferProperty _ _ = return Nothing
405−inferUnary :: UnaryOperator -> Value -> Subst Value
406−inferUnary op (TypedValue val valTy) =
407− case fromMaybe (error "Invalid operator") $ lookup op unaryOps of
408− (valTy', resTy) -> do
410− return $ TypedValue (Unary op val) resTy
411−inferUnary _ _ = error "Invalid arguments to inferUnary"
413−checkUnary :: UnaryOperator -> Value -> Type -> Subst Value
414−checkUnary op val res =
415− case fromMaybe (error "Invalid operator") $ lookup op unaryOps of
416− (valTy, resTy) -> do
418− val' <- check val valTy
419− return $ Unary op val'
421−unaryOps :: [(UnaryOperator, (Type, Type))]
422−unaryOps = [ (Negate, (Number, Number))
423− , (Not, (Boolean, Boolean))
424− , (BitwiseNot, (Number, Number))
427−inferBinary :: BinaryOperator -> Value -> Value -> Subst Value
428−inferBinary op left@(TypedValue _ leftTy) right@(TypedValue _ rightTy) | isEqualityTest op = do
430− return $ TypedValue (Binary op left right) Boolean
431−inferBinary op left@(TypedValue _ leftTy) right@(TypedValue _ rightTy) =
432− case fromMaybe (error "Invalid operator") $ lookup op binaryOps of
433− (valTy, resTy) -> do
436− return $ TypedValue (Binary op left right) resTy
437−inferBinary _ _ _ = error "Invalid arguments to inferBinary"
439−checkBinary :: BinaryOperator -> Value -> Value -> Type -> Subst Value
440−checkBinary op left right res | isEqualityTest op = do
442− left'@(TypedValue _ t1) <- infer left
443− right'@(TypedValue _ t2) <- infer right
445− return $ Binary op left' right'
446−checkBinary op left right res =
447− case fromMaybe (error "Invalid operator") $ lookup op binaryOps of
448− (valTy, resTy) -> do
450− left' <- check left valTy
451− right' <- check right valTy
452− return $ Binary op left' right'
454−isEqualityTest :: BinaryOperator -> Bool
455−isEqualityTest EqualTo = True
456−isEqualityTest NotEqualTo = True
457−isEqualityTest _ = False
459−binaryOps :: [(BinaryOperator, (Type, Type))]
460−binaryOps = [ (Add, (Number, Number))
461− , (Subtract, (Number, Number))
462− , (Multiply, (Number, Number))
463− , (Divide, (Number, Number))
464− , (Modulus, (Number, Number))
465− , (BitwiseAnd, (Number, Number))
466− , (BitwiseOr, (Number, Number))
467− , (BitwiseXor, (Number, Number))
468− , (ShiftRight, (Number, Number))
469− , (ZeroFillShiftRight, (Number, Number))
470− , (And, (Boolean, Boolean))
471− , (Or, (Boolean, Boolean))
472− , (Concat, (String, String))
473− , (Modulus, (Number, Number))
474− , (LessThan, (Number, Boolean))
475− , (LessThanOrEqualTo, (Number, Boolean))
476− , (GreaterThan, (Number, Boolean))
477− , (GreaterThanOrEqualTo, (Number, Boolean))
480−inferBinder :: Type -> Binder -> Subst (M.Map Ident Type)
481−inferBinder _ NullBinder = return M.empty
482−inferBinder val (StringBinder _) = val ~~ String >> return M.empty
483−inferBinder val (NumberBinder _) = val ~~ Number >> return M.empty
484−inferBinder val (BooleanBinder _) = val ~~ Boolean >> return M.empty
485−inferBinder val (VarBinder name) = return $ M.singleton name val
486−inferBinder val (NullaryBinder ctor) = do
488− moduleName <- substCurrentModule <$> ask
489− case M.lookup (qualify moduleName ctor) (dataConstructors env) of
493− _ -> throwError $ "Constructor " ++ show ctor ++ " is not defined"
494−inferBinder val (UnaryBinder ctor binder) = do
496− moduleName <- substCurrentModule <$> ask
497− case M.lookup (qualify moduleName ctor) (dataConstructors env) of
499− fn <- replaceAllVarsWithUnknowns ty
501− Function [obj] ret -> do
503− inferBinder obj binder
504− _ -> throwError $ "Constructor " ++ show ctor ++ " is not a unary constructor"
505− _ -> throwError $ "Constructor " ++ show ctor ++ " is not defined"
506−inferBinder val (ObjectBinder props) = do
509− m1 <- inferRowProperties row rest props
513− inferRowProperties :: Type -> Type -> [(String, Binder)] -> Subst (M.Map Ident Type)
514− inferRowProperties nrow row [] = nrow ~~ row >> return M.empty
515− inferRowProperties nrow row ((name, binder):binders) = do
517− m1 <- inferBinder propTy binder
518− m2 <- inferRowProperties nrow (RCons name propTy row) binders
519− return $ m1 `M.union` m2
520−inferBinder val (ArrayBinder binders) = do
522− m1 <- M.unions <$> mapM (inferBinder el) binders
525−inferBinder val (ConsBinder headBinder tailBinder) = do
527− m1 <- inferBinder el headBinder
528− m2 <- inferBinder val tailBinder
530− return $ m1 `M.union` m2
531−inferBinder val (NamedBinder name binder) = do
532− m <- inferBinder val binder
533− return $ M.insert name val m
535−checkBinders :: [Type] -> Type -> [([Binder], Maybe Guard, Value)] -> Subst [([Binder], Maybe Guard, Value)]
536−checkBinders _ _ [] = return []
537−checkBinders nvals ret ((binders, grd, val):bs) = do
538− moduleName <- substCurrentModule <$> ask
539− m1 <- M.unions <$> zipWithM inferBinder nvals binders
540− r <- bindLocalVariables moduleName (M.toList m1) $ do
541− val' <- check val ret
543− Nothing -> return (binders, Nothing, val')
545− g' <- check g Boolean
546− return (binders, Just g', val')
547− rs <- checkBinders nvals ret bs
550−assignVariable :: Ident -> Subst ()
551−assignVariable name = do
552− env <- checkEnv <$> get
553− moduleName <- substCurrentModule <$> ask
554− case M.lookup (moduleName, name) (names env) of
555− Just (_, LocalVariable) -> throwError $ "Variable with name " ++ show name ++ " already exists."
558−checkStatement :: M.Map Ident Type -> Type -> Statement -> Subst (Bool, M.Map Ident Type, Statement)
559−checkStatement mass _ (VariableIntroduction name val) = do
561− val'@(TypedValue _ t) <- infer val
562− return (False, M.insert name t mass, VariableIntroduction name val')
563−checkStatement mass _ (Assignment ident val) = do
564− val'@(TypedValue _ t) <- infer val
565− case M.lookup ident mass of
566− Nothing -> throwError $ "No local variable with name " ++ show ident
567− Just ty -> do t ~~ ty
568− return (False, mass, Assignment ident val')
569−checkStatement mass ret (While val inner) = do
570− val' <- check val Boolean
571− (allCodePathsReturn, _, inner') <- checkBlock mass ret inner
572− return (allCodePathsReturn, mass, While val' inner')
573−checkStatement mass ret (If ifst) = do
574− (allCodePathsReturn, ifst') <- checkIfStatement mass ret ifst
575− return (allCodePathsReturn, mass, If ifst')
576−checkStatement mass ret (For ident start end inner) = do
577− moduleName <- substCurrentModule <$> ask
578− assignVariable ident
579− start' <- check start Number
580− end' <- check end Number
581− (allCodePathsReturn, _, inner') <- bindLocalVariables moduleName [(ident, Number)] $ checkBlock mass ret inner
582− return (allCodePathsReturn, mass, For ident start' end' inner')
583−checkStatement mass ret (Return val) = do
584− val' <- check val ret
585− return (True, mass, Return val')
587−checkIfStatement :: M.Map Ident Type -> Type -> IfStatement -> Subst (Bool, IfStatement)
588−checkIfStatement mass ret (IfStatement val thens Nothing) = do
589− val' <- check val Boolean
590− (_, _, thens') <- checkBlock mass ret thens
591− return (False, IfStatement val' thens' Nothing)
592−checkIfStatement mass ret (IfStatement val thens (Just elses)) = do
593− val' <- check val Boolean
594− (allCodePathsReturn1, _, thens') <- checkBlock mass ret thens
595− (allCodePathsReturn2, elses') <- checkElseStatement mass ret elses
596− return (allCodePathsReturn1 && allCodePathsReturn2, IfStatement val' thens' (Just elses'))
598−checkElseStatement :: M.Map Ident Type -> Type -> ElseStatement -> Subst (Bool, ElseStatement)
599−checkElseStatement mass ret (Else elses) = do
600− (allCodePathsReturn, _, elses') <- checkBlock mass ret elses
601− return (allCodePathsReturn, Else elses')
602−checkElseStatement mass ret (ElseIf ifst) = (id *** ElseIf) <$> checkIfStatement mass ret ifst
604−checkBlock :: M.Map Ident Type -> Type -> [Statement] -> Subst (Bool, M.Map Ident Type, [Statement])
605−checkBlock mass _ [] = return (False, mass, [])
606−checkBlock mass ret (s:ss) = do
607− moduleName <- substCurrentModule <$> ask
608− (b1, mass1, s') <- checkStatement mass ret s
609− bindLocalVariables moduleName (M.toList mass1) $ case (b1, ss) of
610− (True, []) -> return (True, mass1, [s'])
611− (True, _) -> throwError "Unreachable code"
613− (b, m, ss'') <- checkBlock mass1 ret ss'
614− return (b, m, s':ss'')
616−skolemize :: String -> Type -> Subst Type
617−skolemize ident ty = do
618− tsk <- Skolem <$> fresh'
619− return $ replaceTypeVars ident tsk ty
621−check :: Value -> Type -> Subst Value
622−check val ty = rethrow errorMessage $ check' val ty
625− "Error checking type of term " ++
626− prettyPrintValue val ++
628− prettyPrintType ty ++
632−check' :: Value -> Type -> Subst Value
633−check' val (ForAll idents ty) = do
634− sk <- skolemize idents ty
636−check' val (ConstrainedType constraints ty) = do
638− moduleName <- substCurrentModule <$> ask
639− dictNames <- flip mapM constraints $ \(Qualified _ (ProperName className), _) -> do
640− n <- liftCheck freshDictionaryName
641− return $ Ident $ "__dict_" ++ className ++ "_" ++ show n
642− val' <- withTypeClassDictionaries (zipWith (\name (className, instanceTy) -> (name, [], className, instanceTy)) dictNames (qualifyAllUnqualifiedNames moduleName env constraints)) $ check val ty
643− return $ Abs dictNames val'
644−check' val u@(TUnknown _) = do
645− val'@(TypedValue _ ty) <- infer val
646− -- Don't unify an unknown with an inferred polytype
647− ty' <- replaceAllVarsWithUnknowns ty
650−check' v@(NumericLiteral _) Number = return v
651−check' v@(StringLiteral _) String = return v
652−check' v@(BooleanLiteral _) Boolean = return v
653−check' (Unary op val) ty = checkUnary op val ty
654−check' (Binary op left right) ty = checkBinary op left right ty
655−check' (ArrayLiteral vals) (Array ty) = ArrayLiteral <$> forM vals (\val -> check val ty)
656−check' (Indexer index vals) ty = do
657− index' <- check index Number
658− vals' <- check vals (Array ty)
659− return $ Indexer index' vals'
660−check' (Abs args ret) (Function argTys retTy) = do
661− moduleName <- substCurrentModule <$> ask
662− guardWith "Incorrect number of function arguments" (length args == length argTys)
663− ret' <- bindLocalVariables moduleName (zip args argTys) $ check ret retTy
664− return $ Abs args ret'
665−check' (App f args) ret = do
666− f'@(TypedValue _ ft) <- infer f
667− app <- checkFunctionApplication f' ft args ret
669−check' (Var var) ty = do
670− moduleName <- substCurrentModule <$> ask
671− ty1 <- lookupVariable moduleName var
672− repl <- replaceAllTypeSynonyms ty1
675−check' (TypedValue val ty1) ty2 = do
676− moduleName <- substCurrentModule <$> ask
677− kind <- liftCheck $ kindOf moduleName ty1
678− guardWith ("Expected type of kind *, was " ++ prettyPrintKind kind) $ kind == Star
680− val' <- check val ty1
681− return $ TypedValue val' ty1
682−check' (Case vals binders) ret = do
683− vals' <- mapM infer vals
684− let ts = map (\(TypedValue _ t) -> t) vals'
685− binders' <- checkBinders ts ret binders
686− return $ Case vals' binders'
687−check' (IfThenElse cond th el) ty = do
688− cond' <- check cond Boolean
691− return $ IfThenElse cond' th' el'
692−check' (ObjectLiteral ps) (Object row) = do
693− ensureNoDuplicateProperties ps
694− ps' <- checkProperties ps row False
695− return $ ObjectLiteral ps'
696−check' (ObjectUpdate obj ps) (Object row) = do
697− ensureNoDuplicateProperties ps
698− us <- zip (map fst ps) <$> replicateM (length ps) fresh
699− let (propsToCheck, rest) = rowToList row
700− propsToRemove = map fst ps
701− remainingProps = filter (\(p, _) -> p `notElem` propsToRemove) propsToCheck
702− obj' <- check obj (Object (rowFromList (us ++ remainingProps, rest)))
703− ps' <- checkProperties ps row True
704− return $ ObjectUpdate obj' ps'
705−check' (Accessor prop val) ty = do
707− val' <- check val (Object (RCons prop ty rest))
708− return $ Accessor prop val'
709−check' (Block ss) ret = do
710− (allCodePathsReturn, _, ss') <- checkBlock M.empty ret ss
711− guardWith "Block is missing a return statement" allCodePathsReturn
713−check' (Constructor c) ty = do
715− moduleName <- substCurrentModule <$> ask
716− case M.lookup (qualify moduleName c) (dataConstructors env) of
717− Nothing -> throwError $ "Constructor " ++ show c ++ " is undefined"
719− repl <- replaceAllTypeSynonyms ty1
721− return $ Constructor c
722−check' val (SaturatedTypeSynonym name args) = do
723− ty <- expandTypeSynonym name args
725−check' val ty = throwError $ prettyPrintValue val ++ " does not have type " ++ prettyPrintType ty
727−checkProperties :: [(String, Value)] -> Type -> Bool -> Subst [(String, Value)]
728−checkProperties ps row lax = let (ts, r') = rowToList row in go ps ts r' where
729− go [] [] REmpty = return []
730− go [] [] u@(TUnknown _) = do u ~~ REmpty
732− go [] [] (Skolem _) | lax = return []
733− go [] ((p, _): _) _ | lax = return []
734− | otherwise = throwError $ prettyPrintValue (ObjectLiteral ps) ++ " does not have property " ++ p
735− go ((p,_):_) [] REmpty = throwError $ "Property " ++ p ++ " is not present in closed object type " ++ prettyPrintRow row
736− go ((p,v):ps') [] u@(TUnknown _) = do
737− v'@(TypedValue _ ty) <- infer v
739− u ~~ RCons p ty rest
740− ps'' <- go ps' [] rest
741− return $ (p, v') : ps''
742− go ((p,v):ps') ts r =
745− v'@(TypedValue _ ty) <- infer v
747− r ~~ RCons p ty rest
748− ps'' <- go ps' ts rest
749− return $ (p, v') : ps''
752− ps'' <- go ps' (delete (p, ty) ts) r
753− return $ (p, v') : ps''
754− go _ _ _ = throwError $ prettyPrintValue (ObjectLiteral ps) ++ " does not have type " ++ prettyPrintType (Object row)
756−checkFunctionApplication :: Value -> Type -> [Value] -> Type -> Subst Value
757−checkFunctionApplication fn fnTy args ret = rethrow errorMessage $ checkFunctionApplication' fn fnTy args ret
759− errorMessage msg = "Error applying function of type "
760− ++ prettyPrintType fnTy
761− ++ " to arguments " ++ intercalate ", " (map prettyPrintValue args)
764−checkFunctionApplication' :: Value -> Type -> [Value] -> Type -> Subst Value
765−checkFunctionApplication' fn (Function argTys retTy) args ret = do
766− guardWith "Incorrect number of function arguments" (length args == length argTys)
767− args' <- zipWithM check args argTys
768− retTy `subsumes` ret
769− return $ App fn args'
770−checkFunctionApplication' fn (ForAll ident ty) args ret = do
771− replaced <- replaceVarWithUnknown ident ty
772− checkFunctionApplication fn replaced args ret
773−checkFunctionApplication' fn u@(TUnknown _) args ret = do
774− args' <- mapM (\arg -> infer arg >>= \(TypedValue v t) -> TypedValue v <$> replaceAllVarsWithUnknowns t) args
775− let tys = map (\(TypedValue _ t) -> t) args'
776− u ~~ Function tys ret
777− return $ App fn args'
778−checkFunctionApplication' fn (SaturatedTypeSynonym name tyArgs) args ret = do
779− ty <- expandTypeSynonym name tyArgs
780− checkFunctionApplication fn ty args ret
781−checkFunctionApplication' fn (ConstrainedType constraints fnTy) args ret = do
783− dicts <- getTypeClassDictionaries
784− moduleName <- substCurrentModule <$> ask
785− checkFunctionApplication' (App fn (map (flip TypeClassDictionary dicts) (qualifyAllUnqualifiedNames moduleName env constraints))) fnTy args ret
786−checkFunctionApplication' _ fnTy args ret = throwError $ "Applying a function of type "
787− ++ prettyPrintType fnTy
788− ++ " to argument(s) " ++ intercalate ", " (map prettyPrintValue args)
789− ++ " does not yield a value of type " ++ prettyPrintType ret ++ "."
791−subsumes :: Type -> Type -> Subst ()
792−subsumes (ForAll ident ty1) ty2 = do
793− replaced <- replaceVarWithUnknown ident ty1
794− replaced `subsumes` ty2
795−subsumes (Function args1 ret1) (Function args2 ret2) = do
796− zipWithM_ subsumes args2 args1
797− ret1 `subsumes` ret2
798−subsumes ty1 ty2 = ty1 ~~ ty2