@@ -0,0 +1,799 @@
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