@@ -1,811 +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 (Object r) = Object (apply s r)
57− apply s (Function args ret) = Function (map (apply s) args) (apply s ret)
58− apply s (TypeApp t1 t2) = TypeApp (apply s t1) (apply s t2)
59− apply s (RCons name ty r) = RCons name (apply s ty) (apply s r)
61− unknowns (TUnknown (Unknown u)) = [u]
62− unknowns (SaturatedTypeSynonym _ tys) = concatMap unknowns tys
63− unknowns (ForAll _ ty) = unknowns ty
64− unknowns (Object r) = unknowns r
65− unknowns (Function args ret) = concatMap unknowns args ++ unknowns ret
66− unknowns (TypeApp t1 t2) = unknowns t1 ++ unknowns t2
67− unknowns (RCons _ ty r) = unknowns ty ++ unknowns r
70−unifyTypes :: Type -> Type -> Subst ()
71−unifyTypes t1 t2 = rethrow (\e -> "Error unifying type " ++ prettyPrintType t1 ++ " with type " ++ prettyPrintType t2 ++ ":\n" ++ e) $ do
74− unifyTypes' (TUnknown u1) (TUnknown u2) | u1 == u2 = return ()
75− unifyTypes' (TUnknown u) t = replace u t
76− unifyTypes' t (TUnknown u) = replace u t
77− unifyTypes' (SaturatedTypeSynonym name args) ty = do
78− ty1 <- expandTypeSynonym name args
80− unifyTypes' ty s@(SaturatedTypeSynonym _ _) = s `unifyTypes` ty
81− unifyTypes' (ForAll ident1 ty1) (ForAll ident2 ty2) = do
82− sk <- skolemize ident1 ty1
83− replaced <- replaceVarWithUnknown ident2 ty2
84− sk `unifyTypes` replaced
85− unifyTypes' (ForAll ident ty1) ty2 = do
86− sk <- skolemize ident ty1
88− unifyTypes' ty f@(ForAll _ _) = f `unifyTypes` ty
89− unifyTypes' Number Number = return ()
90− unifyTypes' String String = return ()
91− unifyTypes' Boolean Boolean = return ()
92− unifyTypes' Array Array = return ()
93− unifyTypes' (Object row1) (Object row2) = row1 ~~ row2
94− unifyTypes' (Function args1 ret1) (Function args2 ret2) = do
95− guardWith "Function applied to incorrect number of args" $ length args1 == length args2
96− zipWithM_ unifyTypes args1 args2
97− ret1 `unifyTypes` ret2
98− unifyTypes' (TypeVar v1) (TypeVar v2) | v1 == v2 = return ()
99− unifyTypes' (TypeConstructor c1) (TypeConstructor c2) = do
101− moduleName <- substCurrentModule `fmap` ask
102− guardWith ("Cannot unify " ++ show c1 ++ " with " ++ show c2 ++ ".") (typeConstructorsAreEqual env moduleName c1 c2)
103− unifyTypes' (TypeApp t3 t4) (TypeApp t5 t6) = do
106− unifyTypes' (Skolem s1) (Skolem s2) | s1 == s2 = return ()
107− unifyTypes' r1@(RCons _ _ _) r2 = unifyRows r1 r2
108− unifyTypes' r1 r2@(RCons _ _ _) = unifyRows r1 r2
109− unifyTypes' r1@REmpty r2 = unifyRows r1 r2
110− unifyTypes' r1 r2@REmpty = unifyRows r1 r2
111− unifyTypes' t3 t4 = throwError $ "Cannot unify " ++ prettyPrintType t3 ++ " with " ++ prettyPrintType t4 ++ "."
113−unifyRows :: Type -> Type -> Subst ()
116− (s1, r1') = rowToList r1
117− (s2, r2') = rowToList r2
118− int = [ (t1, t2) | (name, t1) <- s1, (name', t2) <- s2, name == name' ]
119− sd1 = [ (name, t1) | (name, t1) <- s1, name `notElem` map fst s2 ]
120− sd2 = [ (name, t2) | (name, t2) <- s2, name `notElem` map fst s1 ]
122− forM_ int (uncurry (~~))
123− unifyRows' sd1 r1' sd2 r2'
125− unifyRows' :: [(String, Type)] -> Type -> [(String, Type)] -> Type -> Subst ()
126− unifyRows' [] (TUnknown u) sd r = replace u (rowFromList (sd, r))
127− unifyRows' sd r [] (TUnknown u) = replace u (rowFromList (sd, r))
128− unifyRows' ((name, ty):row) r others u@(TUnknown un) = do
130− forM_ row $ \(_, t) -> occursCheck un t
132− u ~~ RCons name ty u'
133− unifyRows' row r others u'
134− unifyRows' [] REmpty [] REmpty = return ()
135− unifyRows' [] (TypeVar v1) [] (TypeVar v2) | v1 == v2 = return ()
136− unifyRows' [] (Skolem s1) [] (Skolem s2) | s1 == s2 = return ()
137− unifyRows' sd3 r3 sd4 r4 = throwError $ "Cannot unify " ++ prettyPrintRow (rowFromList (sd3, r3)) ++ " with " ++ prettyPrintRow (rowFromList (sd4, r4)) ++ "."
139−typeConstructorsAreEqual :: Environment -> ModuleName -> Qualified ProperName -> Qualified ProperName -> Bool
140−typeConstructorsAreEqual env moduleName = (==) `on` canonicalizeType moduleName env
142−typesOf :: ModuleName -> [(Ident, Value)] -> Check [(Ident, (Value, Type))]
143−typesOf moduleName vals = do
144− tys <- fmap (\(tys, s) -> map (\(ident, (val, ty)) -> (ident, (overTypes (apply s) val, apply s ty))) tys)
145− . runSubst (SubstContext moduleName) $ do
146− let es = map isTyped vals
147− typed = filter (isJust . snd . snd) es
148− untyped = filter (isNothing . snd . snd) es
149− typedDict = map (\(ident, (_, Just ty)) -> (ident, ty)) typed
150− untypedNames <- replicateM (length untyped) fresh
151− let untypedDict = zip (map fst untyped) untypedNames
152− dict = M.fromList (map (\(ident, ty) -> ((moduleName, ident), (ty, LocalVariable))) $ (map (id *** fst) typedDict) ++ untypedDict)
154− triple@(_, (val, ty)) <- case e of
155− (ident, (val, Just (ty, checkType))) -> do
156− kind <- liftCheck $ kindOf moduleName ty
157− guardWith ("Expected type of kind *, was " ++ prettyPrintKind kind) $ kind == Star
158− ty' <- replaceAllTypeSynonyms ty
159− val' <- bindNames dict $ if checkType then check val ty' else return val
160− return (ident, (val', ty'))
161− (ident, (val, Nothing)) -> do
162− TypedValue _ val' ty <- bindNames dict $ infer val
163− ty ~~ fromMaybe (error "name not found in dictionary") (lookup ident untypedDict)
164− return (ident, (val', ty))
165− when (moduleName == ModuleName (ProperName "Main") && fst e == Ident "main") $ do
166− [eff, a] <- replicateM 2 fresh
167− ty ~~ TypeApp (TypeApp (TypeConstructor (Qualified (Just (ModuleName (ProperName "Eff"))) (ProperName "Eff"))) eff) a
170− forM_ tys $ skolemEscapeCheck . snd . snd
171− forM tys $ \(ident, (val, ty)) -> do
172− val' <- replaceTypeClassDictionaries moduleName val
173− return (ident, (overTypes (desaturateAllTypeSynonyms . setifyAll) $ val'
174− , varIfUnknown . desaturateAllTypeSynonyms . setifyAll $ ty))
176−isTyped :: (Ident, Value) -> (Ident, (Value, Maybe (Type, Bool)))
177−isTyped (name, TypedValue checkType value ty) = (name, (value, Just (ty, checkType)))
178−isTyped (name, value) = (name, (value, Nothing))
180−overTypes :: (Type -> Type) -> Value -> Value
181−overTypes f = everywhere (mkT f)
183−replaceTypeClassDictionaries :: ModuleName -> Value -> Check Value
184−replaceTypeClassDictionaries mn = everywhereM (mkM go)
186− go (TypeClassDictionary constraint dicts) = entails mn dicts constraint
187− go other = return other
189−entails :: ModuleName -> [TypeClassDictionaryInScope] -> (Qualified ProperName, Type) -> Check Value
190−entails moduleName context goal@(className, ty) = do
193− [] -> throwError $ "No " ++ show className ++ " instance found for " ++ prettyPrintType ty
194− (dict : _) -> return dict
196− go env (className', ty') =
197− [ mkDictionary (canonicalizeDictionary tcd) args
200− , typeConstructorsAreEqual env moduleName className' (tcdClassName tcd)
201− , subst <- maybeToList $ typeHeadsAreEqual moduleName env ty' (tcdInstanceType tcd)
202− , args <- solveSubgoals env subst (tcdDependencies tcd) ]
203− solveSubgoals _ _ Nothing = return Nothing
204− solveSubgoals env subst (Just subgoals) = do
205− dict <- mapM (go env) (replaceAllTypeVars subst subgoals)
207− mkDictionary fnName args = maybe id (flip App) args $ (Var fnName)
208− filterModule (TypeClassDictionaryInScope { tcdName = Qualified (Just mn) _ }) | mn == moduleName = True
209− filterModule (TypeClassDictionaryInScope { tcdName = Qualified Nothing _ }) = True
210− filterModule _ = False
211− canonicalizeDictionary (TypeClassDictionaryInScope { tcdType = TCDRegular, tcdName = nm }) = nm
212− canonicalizeDictionary (TypeClassDictionaryInScope { tcdType = TCDAlias nm }) = nm
214−typeHeadsAreEqual :: ModuleName -> Environment -> Type -> Type -> Maybe [(String, Type)]
215−typeHeadsAreEqual _ _ String String = Just []
216−typeHeadsAreEqual _ _ Number Number = Just []
217−typeHeadsAreEqual _ _ Boolean Boolean = Just []
218−typeHeadsAreEqual _ _ (Skolem s1) (Skolem s2) | s1 == s2 = Just []
219−typeHeadsAreEqual _ _ Array Array = Just []
220−typeHeadsAreEqual m e (TypeConstructor c1) (TypeConstructor c2) | typeConstructorsAreEqual e m c1 c2 = Just []
221−typeHeadsAreEqual m e (TypeApp h1 (TypeVar v)) (TypeApp h2 arg) = (:) (v, arg) <$> typeHeadsAreEqual m e h1 h2
222−typeHeadsAreEqual m e t1@(TypeApp _ _) t2@(TypeApp _ (TypeVar _)) = typeHeadsAreEqual m e t2 t1
223−typeHeadsAreEqual _ _ _ _ = Nothing
225−escapeCheck :: Value -> Type -> Subst ()
226−escapeCheck value ty = do
227− subst <- substSubst <$> getSubstState
228− let visibleUnknowns = nub $ unknowns $ apply subst ty
229− let allUnknowns = findAllTypes value
230− forM_ allUnknowns $ \t -> do
231− let unsolvedUnknowns = nub . unknowns $ apply subst t
232− guardWith "Escape check fails" $ null $ unsolvedUnknowns \\ visibleUnknowns
234−findAllTypes :: Value -> [Type]
235−findAllTypes = everything (++) (mkQ [] go)
237− go (TypedValue _ _ ty) = [ty]
240−skolemEscapeCheck :: Type -> Check ()
241−skolemEscapeCheck ty =
242− case something (mkQ Nothing findSkolems) ty of
243− Nothing -> return ()
244− Just _ -> throwError $ "Skolem variables cannot escape. Consider adding a type signature." ++ show ty
246− findSkolems (Skolem _) = return ()
247− findSkolems _ = mzero
249−setify :: Type -> Type
250−setify = rowFromList . first (M.toList . M.fromList) . rowToList
252−setifyAll :: (D.Data d) => d -> d
253−setifyAll = everywhere (mkT setify)
255−varIfUnknown :: Type -> Type
257− let unks = nub $ unknowns ty
258− toName = (:) 't' . show
259− ty' = everywhere (mkT typeToVar) $ ty
260− typeToVar :: Type -> Type
261− typeToVar (TUnknown (Unknown u)) = TypeVar (toName u)
263− in mkForAll (sort . map toName $ unks) ty'
265−replaceAllTypeVars :: (D.Data d) => [(String, Type)] -> d -> d
266−replaceAllTypeVars = foldl' (\f (name, ty) -> replaceTypeVars name ty . f) id
268−replaceAllVarsWithUnknowns :: Type -> Subst Type
269−replaceAllVarsWithUnknowns (ForAll ident ty) = replaceVarWithUnknown ident ty >>= replaceAllVarsWithUnknowns
270−replaceAllVarsWithUnknowns ty = return ty
272−replaceVarWithUnknown :: String -> Type -> Subst Type
273−replaceVarWithUnknown ident ty = do
275− return $ replaceTypeVars ident tu $ ty
277−replaceAllTypeSynonyms :: (Functor m, MonadState CheckState m, MonadReader SubstContext m, MonadError String m) => (D.Data d) => d -> m d
278−replaceAllTypeSynonyms d = do
280− moduleName <- substCurrentModule <$> ask
281− let syns = map (\((path, name), (args, _)) -> ((path, name), length args)) . M.toList $ typeSynonyms env
282− either throwError return $ saturateAllTypeSynonyms env moduleName syns d
284−desaturateAllTypeSynonyms :: (D.Data d) => d -> d
285−desaturateAllTypeSynonyms = everywhere (mkT replaceSaturatedTypeSynonym)
287− replaceSaturatedTypeSynonym (SaturatedTypeSynonym name args) = foldl TypeApp (TypeConstructor name) args
288− replaceSaturatedTypeSynonym t = t
290−expandTypeSynonym :: Qualified ProperName -> [Type] -> Subst Type
291−expandTypeSynonym name args = do
293− moduleName <- substCurrentModule `fmap` ask
294− case M.lookup (canonicalizeType moduleName env name) (typeSynonyms env) of
295− Just (synArgs, body) -> return $ replaceAllTypeVars (zip synArgs args) body
296− Nothing -> error "Type synonym was not defined"
298−ensureNoDuplicateProperties :: (MonadError String m) => [(String, Value)] -> m ()
299−ensureNoDuplicateProperties ps = guardWith "Duplicate property names" $ length (nub . map fst $ ps) == length ps
301−infer :: Value -> Subst Value
302−infer val = rethrow (\e -> "Error inferring type of term " ++ prettyPrintValue val ++ ":\n" ++ e) $ infer' val
304−infer' :: Value -> Subst Value
305−infer' v@(NumericLiteral _) = return $ TypedValue True v Number
306−infer' v@(StringLiteral _) = return $ TypedValue True v String
307−infer' v@(BooleanLiteral _) = return $ TypedValue True v Boolean
308−infer' (ArrayLiteral vals) = do
309− ts <- mapM infer vals
311− forM_ ts $ \(TypedValue _ _ t) -> els ~~ TypeApp Array t
312− return $ TypedValue True (ArrayLiteral ts) els
313−infer' (Unary op val) = do
316−infer' (Binary op left right) = do
319− inferBinary op v1 v2
320−infer' (ObjectLiteral ps) = do
321− ensureNoDuplicateProperties ps
322− ts <- mapM (infer . snd) ps
323− let fields = zipWith (\name (TypedValue _ _ t) -> (name, t)) (map fst ps) ts
324− ty = Object $ rowFromList (fields, REmpty)
325− return $ TypedValue True (ObjectLiteral (zip (map fst ps) ts)) ty
326−infer' (ObjectUpdate o ps) = do
327− ensureNoDuplicateProperties ps
329− newVals <- zipWith (\(name, _) t -> (name, t)) ps <$> mapM (infer . snd) ps
330− let newTys = map (\(name, TypedValue _ _ ty) -> (name, ty)) newVals
331− oldTys <- zip (map fst ps) <$> replicateM (length ps) fresh
332− o' <- check o $ Object $ rowFromList (oldTys, row)
333− return $ TypedValue True (ObjectUpdate o' newVals) $ Object $ rowFromList (newTys, row)
334−infer' (Indexer index val) = do
336− index' <- check index Number
337− val' <- check val (TypeApp Array el)
338− return $ TypedValue True (Indexer (TypedValue True index' Number) (TypedValue True val' (TypeApp Array el))) el
339−infer' (Accessor prop val) = do
340− typed@(TypedValue _ _ objTy) <- infer val
341− propTy <- inferProperty objTy prop
346− objTy `subsumes` Object (RCons prop field rest)
347− return $ TypedValue True (Accessor prop typed) field
348− Just ty -> return $ TypedValue True (Accessor prop typed) ty
349−infer' (Abs args ret) = do
350− ts <- replicateM (length args) fresh
351− moduleName <- substCurrentModule <$> ask
352− bindLocalVariables moduleName (zip args ts) $ do
353− body@(TypedValue _ _ bodyTy) <- infer' ret
354− return $ TypedValue True (Abs args body) $ Function ts bodyTy
355−infer' (App f args) = do
356− f'@(TypedValue _ _ ft) <- infer f
358− app <- checkFunctionApplication f' ft args ret
359− return $ TypedValue True app ret
360−infer' (Var var) = do
361− moduleName <- substCurrentModule <$> ask
362− ty <- lookupVariable moduleName var
363− ty' <- replaceAllTypeSynonyms ty
365− ConstrainedType constraints _ -> do
367− dicts <- getTypeClassDictionaries
368− return $ TypedValue True (App (Var var) (map (flip TypeClassDictionary dicts) (qualifyAllUnqualifiedNames moduleName env constraints))) ty'
369− _ -> return $ TypedValue True (Var var) ty'
370−infer' (Block ss) = do
372− (allCodePathsReturn, _, ss') <- checkBlock M.empty ret ss
373− guardWith "Block is missing a return statement" allCodePathsReturn
374− return $ TypedValue True (Block ss') ret
375−infer' v@(Constructor c) = do
377− moduleName <- substCurrentModule `fmap` ask
378− case M.lookup (qualify moduleName c) (dataConstructors env) of
379− Nothing -> throwError $ "Constructor " ++ show c ++ " is undefined"
380− Just (ty, _) -> do ty' <- replaceAllTypeSynonyms ty
381− return $ TypedValue True v ty'
382−infer' (Case vals binders) = do
383− ts <- mapM infer vals
385− binders' <- checkBinders (map (\(TypedValue _ _ t) -> t) ts) ret binders
386− return $ TypedValue True (Case ts binders') ret
387−infer' (IfThenElse cond th el) = do
388− cond' <- check cond Boolean
389− v2@(TypedValue _ _ t2) <- infer th
390− v3@(TypedValue _ _ t3) <- infer el
392− return $ TypedValue True (IfThenElse cond' v2 v3) t2
393−infer' (TypedValue checkType val ty) = do
394− moduleName <- substCurrentModule <$> ask
395− kind <- liftCheck $ kindOf moduleName ty
396− guardWith ("Expected type of kind *, was " ++ prettyPrintKind kind) $ kind == Star
397− ty' <- replaceAllTypeSynonyms ty
398− val' <- if checkType then check val ty' else return val
399− return $ TypedValue True val' ty
400−infer' _ = error "Invalid argument to infer"
402−inferProperty :: Type -> String -> Subst (Maybe Type)
403−inferProperty (Object row) prop = do
404− let (props, _) = rowToList row
405− return $ lookup prop props
406−inferProperty (SaturatedTypeSynonym name args) prop = do
407− replaced <- expandTypeSynonym name args
408− inferProperty replaced prop
409−inferProperty (ForAll ident ty) prop = do
410− replaced <- replaceVarWithUnknown ident ty
411− inferProperty replaced prop
412−inferProperty _ _ = return Nothing
414−inferUnary :: UnaryOperator -> Value -> Subst Value
415−inferUnary op (TypedValue _ val valTy) =
416− case fromMaybe (error "Invalid operator") $ lookup op unaryOps of
417− (valTy', resTy) -> do
419− return $ TypedValue True (Unary op val) resTy
420−inferUnary _ _ = error "Invalid arguments to inferUnary"
422−checkUnary :: UnaryOperator -> Value -> Type -> Subst Value
423−checkUnary op val res =
424− case fromMaybe (error "Invalid operator") $ lookup op unaryOps of
425− (valTy, resTy) -> do
427− val' <- check val valTy
428− return $ Unary op val'
430−unaryOps :: [(UnaryOperator, (Type, Type))]
431−unaryOps = [ (Negate, (Number, Number))
432− , (Not, (Boolean, Boolean))
433− , (BitwiseNot, (Number, Number))
436−inferBinary :: BinaryOperator -> Value -> Value -> Subst Value
437−inferBinary op left@(TypedValue _ _ leftTy) right@(TypedValue _ _ rightTy) | isEqualityTest op = do
439− return $ TypedValue True (Binary op left right) Boolean
440−inferBinary op left@(TypedValue _ _ leftTy) right@(TypedValue _ _ rightTy) =
441− case fromMaybe (error "Invalid operator") $ lookup op binaryOps of
442− (valTy, resTy) -> do
445− return $ TypedValue True (Binary op left right) resTy
446−inferBinary _ _ _ = error "Invalid arguments to inferBinary"
448−checkBinary :: BinaryOperator -> Value -> Value -> Type -> Subst Value
449−checkBinary op left right res | isEqualityTest op = do
451− left'@(TypedValue _ _ t1) <- infer left
452− right'@(TypedValue _ _ t2) <- infer right
454− return $ Binary op left' right'
455−checkBinary op left right res =
456− case fromMaybe (error "Invalid operator") $ lookup op binaryOps of
457− (valTy, resTy) -> do
459− left' <- check left valTy
460− right' <- check right valTy
461− return $ Binary op left' right'
463−isEqualityTest :: BinaryOperator -> Bool
464−isEqualityTest EqualTo = True
465−isEqualityTest NotEqualTo = True
466−isEqualityTest _ = False
468−binaryOps :: [(BinaryOperator, (Type, Type))]
469−binaryOps = [ (Add, (Number, Number))
470− , (Subtract, (Number, Number))
471− , (Multiply, (Number, Number))
472− , (Divide, (Number, Number))
473− , (Modulus, (Number, Number))
474− , (BitwiseAnd, (Number, Number))
475− , (BitwiseOr, (Number, Number))
476− , (BitwiseXor, (Number, Number))
477− , (ShiftRight, (Number, Number))
478− , (ZeroFillShiftRight, (Number, Number))
479− , (And, (Boolean, Boolean))
480− , (Or, (Boolean, Boolean))
481− , (Concat, (String, String))
482− , (Modulus, (Number, Number))
483− , (LessThan, (Number, Boolean))
484− , (LessThanOrEqualTo, (Number, Boolean))
485− , (GreaterThan, (Number, Boolean))
486− , (GreaterThanOrEqualTo, (Number, Boolean))
489−inferBinder :: Type -> Binder -> Subst (M.Map Ident Type)
490−inferBinder _ NullBinder = return M.empty
491−inferBinder val (StringBinder _) = val ~~ String >> return M.empty
492−inferBinder val (NumberBinder _) = val ~~ Number >> return M.empty
493−inferBinder val (BooleanBinder _) = val ~~ Boolean >> return M.empty
494−inferBinder val (VarBinder name) = return $ M.singleton name val
495−inferBinder val (NullaryBinder ctor) = do
497− moduleName <- substCurrentModule <$> ask
498− case M.lookup (qualify moduleName ctor) (dataConstructors env) of
502− _ -> throwError $ "Constructor " ++ show ctor ++ " is not defined"
503−inferBinder val (UnaryBinder ctor binder) = do
505− moduleName <- substCurrentModule <$> ask
506− case M.lookup (qualify moduleName ctor) (dataConstructors env) of
508− fn <- replaceAllVarsWithUnknowns ty
510− Function [obj] ret -> do
512− inferBinder obj binder
513− _ -> throwError $ "Constructor " ++ show ctor ++ " is not a unary constructor"
514− _ -> throwError $ "Constructor " ++ show ctor ++ " is not defined"
515−inferBinder val (ObjectBinder props) = do
518− m1 <- inferRowProperties row rest props
522− inferRowProperties :: Type -> Type -> [(String, Binder)] -> Subst (M.Map Ident Type)
523− inferRowProperties nrow row [] = nrow ~~ row >> return M.empty
524− inferRowProperties nrow row ((name, binder):binders) = do
526− m1 <- inferBinder propTy binder
527− m2 <- inferRowProperties nrow (RCons name propTy row) binders
528− return $ m1 `M.union` m2
529−inferBinder val (ArrayBinder binders) = do
531− m1 <- M.unions <$> mapM (inferBinder el) binders
532− val ~~ TypeApp Array el
534−inferBinder val (ConsBinder headBinder tailBinder) = do
536− m1 <- inferBinder el headBinder
537− m2 <- inferBinder val tailBinder
538− val ~~ TypeApp Array el
539− return $ m1 `M.union` m2
540−inferBinder val (NamedBinder name binder) = do
541− m <- inferBinder val binder
542− return $ M.insert name val m
544−checkBinders :: [Type] -> Type -> [([Binder], Maybe Guard, Value)] -> Subst [([Binder], Maybe Guard, Value)]
545−checkBinders _ _ [] = return []
546−checkBinders nvals ret ((binders, grd, val):bs) = do
547− moduleName <- substCurrentModule <$> ask
548− m1 <- M.unions <$> zipWithM inferBinder nvals binders
549− r <- bindLocalVariables moduleName (M.toList m1) $ do
550− val' <- check val ret
552− Nothing -> return (binders, Nothing, val')
554− g' <- check g Boolean
555− return (binders, Just g', val')
556− rs <- checkBinders nvals ret bs
559−assignVariable :: Ident -> Subst ()
560−assignVariable name = do
561− env <- checkEnv <$> get
562− moduleName <- substCurrentModule <$> ask
563− case M.lookup (moduleName, name) (names env) of
564− Just (_, LocalVariable) -> throwError $ "Variable with name " ++ show name ++ " already exists."
567−checkStatement :: M.Map Ident Type -> Type -> Statement -> Subst (Bool, M.Map Ident Type, Statement)
568−checkStatement mass _ (VariableIntroduction name val) = do
570− val'@(TypedValue _ _ t) <- infer val
571− return (False, M.insert name t mass, VariableIntroduction name val')
572−checkStatement mass _ (Assignment ident val) = do
573− val'@(TypedValue _ _ t) <- infer val
574− case M.lookup ident mass of
575− Nothing -> throwError $ "No local variable with name " ++ show ident
576− Just ty -> do t ~~ ty
577− return (False, mass, Assignment ident val')
578−checkStatement mass ret (While val inner) = do
579− val' <- check val Boolean
580− (allCodePathsReturn, _, inner') <- checkBlock mass ret inner
581− return (allCodePathsReturn, mass, While val' inner')
582−checkStatement mass ret (If ifst) = do
583− (allCodePathsReturn, ifst') <- checkIfStatement mass ret ifst
584− return (allCodePathsReturn, mass, If ifst')
585−checkStatement mass ret (For ident start end inner) = do
586− moduleName <- substCurrentModule <$> ask
587− assignVariable ident
588− start' <- check start Number
589− end' <- check end Number
590− (allCodePathsReturn, _, inner') <- bindLocalVariables moduleName [(ident, Number)] $ checkBlock mass ret inner
591− return (allCodePathsReturn, mass, For ident start' end' inner')
592−checkStatement mass ret (Return val) = do
593− val' <- check val ret
594− return (True, mass, Return val')
596−checkIfStatement :: M.Map Ident Type -> Type -> IfStatement -> Subst (Bool, IfStatement)
597−checkIfStatement mass ret (IfStatement val thens Nothing) = do
598− val' <- check val Boolean
599− (_, _, thens') <- checkBlock mass ret thens
600− return (False, IfStatement val' thens' Nothing)
601−checkIfStatement mass ret (IfStatement val thens (Just elses)) = do
602− val' <- check val Boolean
603− (allCodePathsReturn1, _, thens') <- checkBlock mass ret thens
604− (allCodePathsReturn2, elses') <- checkElseStatement mass ret elses
605− return (allCodePathsReturn1 && allCodePathsReturn2, IfStatement val' thens' (Just elses'))
607−checkElseStatement :: M.Map Ident Type -> Type -> ElseStatement -> Subst (Bool, ElseStatement)
608−checkElseStatement mass ret (Else elses) = do
609− (allCodePathsReturn, _, elses') <- checkBlock mass ret elses
610− return (allCodePathsReturn, Else elses')
611−checkElseStatement mass ret (ElseIf ifst) = (id *** ElseIf) <$> checkIfStatement mass ret ifst
613−checkBlock :: M.Map Ident Type -> Type -> [Statement] -> Subst (Bool, M.Map Ident Type, [Statement])
614−checkBlock mass _ [] = return (False, mass, [])
615−checkBlock mass ret (s:ss) = do
616− moduleName <- substCurrentModule <$> ask
617− (b1, mass1, s') <- checkStatement mass ret s
618− bindLocalVariables moduleName (M.toList mass1) $ case (b1, ss) of
619− (True, []) -> return (True, mass1, [s'])
620− (True, _) -> throwError "Unreachable code"
622− (b, m, ss'') <- checkBlock mass1 ret ss'
623− return (b, m, s':ss'')
625−skolemize :: String -> Type -> Subst Type
626−skolemize ident ty = do
627− tsk <- Skolem <$> fresh'
628− return $ replaceTypeVars ident tsk ty
630−check :: Value -> Type -> Subst Value
631−check val ty = rethrow errorMessage $ check' val ty
634− "Error checking type of term " ++
635− prettyPrintValue val ++
637− prettyPrintType ty ++
641−check' :: Value -> Type -> Subst Value
642−check' val (ForAll idents ty) = do
643− sk <- skolemize idents ty
645−check' val (ConstrainedType constraints ty) = do
647− moduleName <- substCurrentModule <$> ask
648− dictNames <- flip mapM constraints $ \(Qualified _ (ProperName className), _) -> do
649− n <- liftCheck freshDictionaryName
650− return $ Ident $ "__dict_" ++ className ++ "_" ++ show n
651− val' <- withTypeClassDictionaries (zipWith (\name (className, instanceTy) ->
652− TypeClassDictionaryInScope name className instanceTy Nothing TCDRegular) (map (Qualified Nothing) dictNames)
653− (qualifyAllUnqualifiedNames moduleName env constraints)) $
655− return $ Abs dictNames val'
656−check' val u@(TUnknown _) = do
657− val'@(TypedValue _ _ ty) <- infer val
658− -- Don't unify an unknown with an inferred polytype
659− ty' <- replaceAllVarsWithUnknowns ty
662−check' v@(NumericLiteral _) Number = return v
663−check' v@(StringLiteral _) String = return v
664−check' v@(BooleanLiteral _) Boolean = return v
665−check' (Unary op val) ty = checkUnary op val ty
666−check' (Binary op left right) ty = checkBinary op left right ty
667−check' (ArrayLiteral vals) (TypeApp Array ty) = ArrayLiteral <$> forM vals (\val -> check val ty)
668−check' (Indexer index vals) ty = do
669− index' <- check index Number
670− vals' <- check vals (TypeApp Array ty)
671− return $ Indexer index' vals'
672−check' (Abs args ret) (Function argTys retTy) = do
673− moduleName <- substCurrentModule <$> ask
674− guardWith "Incorrect number of function arguments" (length args == length argTys)
675− ret' <- bindLocalVariables moduleName (zip args argTys) $ check ret retTy
676− return $ Abs args ret'
677−check' (App f args) ret = do
678− f'@(TypedValue _ _ ft) <- infer f
679− app <- checkFunctionApplication f' ft args ret
681−check' (Var var) ty = do
682− moduleName <- substCurrentModule <$> ask
683− ty1 <- lookupVariable moduleName var
684− repl <- replaceAllTypeSynonyms ty1
687−check' (TypedValue checkType val ty1) ty2 = do
688− moduleName <- substCurrentModule <$> ask
689− kind <- liftCheck $ kindOf moduleName ty1
690− guardWith ("Expected type of kind *, was " ++ prettyPrintKind kind) $ kind == Star
692− val' <- if checkType then check val ty1 else return val
693− return $ TypedValue True val' ty1
694−check' (Case vals binders) ret = do
695− vals' <- mapM infer vals
696− let ts = map (\(TypedValue _ _ t) -> t) vals'
697− binders' <- checkBinders ts ret binders
698− return $ Case vals' binders'
699−check' (IfThenElse cond th el) ty = do
700− cond' <- check cond Boolean
703− return $ IfThenElse cond' th' el'
704−check' (ObjectLiteral ps) (Object row) = do
705− ensureNoDuplicateProperties ps
706− ps' <- checkProperties ps row False
707− return $ ObjectLiteral ps'
708−check' (ObjectUpdate obj ps) (Object row) = do
709− ensureNoDuplicateProperties ps
710− us <- zip (map fst ps) <$> replicateM (length ps) fresh
711− let (propsToCheck, rest) = rowToList row
712− propsToRemove = map fst ps
713− remainingProps = filter (\(p, _) -> p `notElem` propsToRemove) propsToCheck
714− obj' <- check obj (Object (rowFromList (us ++ remainingProps, rest)))
715− ps' <- checkProperties ps row True
716− return $ ObjectUpdate obj' ps'
717−check' (Accessor prop val) ty = do
719− val' <- check val (Object (RCons prop ty rest))
720− return $ Accessor prop val'
721−check' (Block ss) ret = do
722− (allCodePathsReturn, _, ss') <- checkBlock M.empty ret ss
723− guardWith "Block is missing a return statement" allCodePathsReturn
725−check' (Constructor c) ty = do
727− moduleName <- substCurrentModule <$> ask
728− case M.lookup (qualify moduleName c) (dataConstructors env) of
729− Nothing -> throwError $ "Constructor " ++ show c ++ " is undefined"
731− repl <- replaceAllTypeSynonyms ty1
733− return $ Constructor c
734−check' val (SaturatedTypeSynonym name args) = do
735− ty <- expandTypeSynonym name args
737−check' val ty = throwError $ prettyPrintValue val ++ " does not have type " ++ prettyPrintType ty
739−checkProperties :: [(String, Value)] -> Type -> Bool -> Subst [(String, Value)]
740−checkProperties ps row lax = let (ts, r') = rowToList row in go ps ts r' where
741− go [] [] REmpty = return []
742− go [] [] u@(TUnknown _) = do u ~~ REmpty
744− go [] [] (Skolem _) | lax = return []
745− go [] ((p, _): _) _ | lax = return []
746− | otherwise = throwError $ prettyPrintValue (ObjectLiteral ps) ++ " does not have property " ++ p
747− go ((p,_):_) [] REmpty = throwError $ "Property " ++ p ++ " is not present in closed object type " ++ prettyPrintRow row
748− go ((p,v):ps') [] u@(TUnknown _) = do
749− v'@(TypedValue _ _ ty) <- infer v
751− u ~~ RCons p ty rest
752− ps'' <- go ps' [] rest
753− return $ (p, v') : ps''
754− go ((p,v):ps') ts r =
757− v'@(TypedValue _ _ ty) <- infer v
759− r ~~ RCons p ty rest
760− ps'' <- go ps' ts rest
761− return $ (p, v') : ps''
764− ps'' <- go ps' (delete (p, ty) ts) r
765− return $ (p, v') : ps''
766− go _ _ _ = throwError $ prettyPrintValue (ObjectLiteral ps) ++ " does not have type " ++ prettyPrintType (Object row)
768−checkFunctionApplication :: Value -> Type -> [Value] -> Type -> Subst Value
769−checkFunctionApplication fn fnTy args ret = rethrow errorMessage $ checkFunctionApplication' fn fnTy args ret
771− errorMessage msg = "Error applying function of type "
772− ++ prettyPrintType fnTy
773− ++ " to arguments " ++ intercalate ", " (map prettyPrintValue args)
776−checkFunctionApplication' :: Value -> Type -> [Value] -> Type -> Subst Value
777−checkFunctionApplication' fn (Function argTys retTy) args ret = do
778− guardWith "Incorrect number of function arguments" (length args == length argTys)
779− args' <- zipWithM check args argTys
780− retTy `subsumes` ret
781− return $ App fn args'
782−checkFunctionApplication' fn (ForAll ident ty) args ret = do
783− replaced <- replaceVarWithUnknown ident ty
784− checkFunctionApplication fn replaced args ret
785−checkFunctionApplication' fn u@(TUnknown _) args ret = do
786− args' <- mapM (\arg -> infer arg >>= \(TypedValue _ v t) -> TypedValue True v <$> replaceAllVarsWithUnknowns t) args
787− let tys = map (\(TypedValue _ _ t) -> t) args'
788− u ~~ Function tys ret
789− return $ App fn args'
790−checkFunctionApplication' fn (SaturatedTypeSynonym name tyArgs) args ret = do
791− ty <- expandTypeSynonym name tyArgs
792− checkFunctionApplication fn ty args ret
793−checkFunctionApplication' fn (ConstrainedType constraints fnTy) args ret = do
795− dicts <- getTypeClassDictionaries
796− moduleName <- substCurrentModule <$> ask
797− checkFunctionApplication' (App fn (map (flip TypeClassDictionary dicts) (qualifyAllUnqualifiedNames moduleName env constraints))) fnTy args ret
798−checkFunctionApplication' _ fnTy args ret = throwError $ "Applying a function of type "
799− ++ prettyPrintType fnTy
800− ++ " to argument(s) " ++ intercalate ", " (map prettyPrintValue args)
801− ++ " does not yield a value of type " ++ prettyPrintType ret ++ "."
803−subsumes :: Type -> Type -> Subst ()
804−subsumes (ForAll ident ty1) ty2 = do
805− replaced <- replaceVarWithUnknown ident ty1
806− replaced `subsumes` ty2
807−subsumes (Function args1 ret1) (Function args2 ret2) = do
808− zipWithM_ subsumes args2 args1
809− ret1 `subsumes` ret2
810−subsumes ty1 ty2 = ty1 ~~ ty2