@@ -1,643 +0,0 @@
1−-----------------------------------------------------------------------------
2−--
3−-- Module : Language.PureScript.TypeChecker.Types
4−-- Copyright : (c) Phil Freeman 2013
5−-- License : MIT
6−--
7−-- Maintainer : Phil Freeman <paf31@cantab.net>
8−-- Stability : experimental
9−-- Portability :
10−--
11−-- |
12−--
13−-----------------------------------------------------------------------------
14−
15−{-# LANGUAGE DeriveDataTypeable #-}
16−
17−module Language.PureScript.TypeChecker.Types (
18− TypeConstraint(..),
19− TypeSolution(..),
20− typeOf
21−) where
22−
23−import Debug.Trace
24−
25−import Data.List
26−import Data.Function
27−import qualified Data.Data as D
28−import Data.Generics (everywhere, everywhereM, everything, mkT, mkM, mkQ, extM, extQ)
29−
30−import Language.PureScript.Values
31−import Language.PureScript.Types
32−import Language.PureScript.Kinds
33−import Language.PureScript.Names
34−import Language.PureScript.TypeChecker.Monad
35−import Language.PureScript.TypeChecker.Kinds
36−import Language.PureScript.TypeChecker.Synonyms
37−import Language.PureScript.Pretty
38−
39−import Control.Monad.State
40−import Control.Monad.Error
41−
42−import Control.Applicative
43−import Control.Arrow (Kleisli(..), (***), (&&&), first)
44−import qualified Control.Category as C
45−
46−import qualified Data.Map as M
47−
48−data TypeConstraintOrigin
49− = ValueOrigin Value
50− | BinderOrigin Binder
51− | AssignmentTargetOrigin Ident deriving (Show, D.Data, D.Typeable)
52−
53−prettyPrintOrigin :: TypeConstraintOrigin -> String
54−prettyPrintOrigin (ValueOrigin val) = prettyPrintValue val
55−prettyPrintOrigin (BinderOrigin binder) = prettyPrintBinder binder
56−prettyPrintOrigin (AssignmentTargetOrigin ident) = show ident
57−
58−data TypeConstraint
59− = TypeConstraint Int Type TypeConstraintOrigin
60− | RowConstraint Int Row TypeConstraintOrigin deriving (Show, D.Data, D.Typeable)
61−
62−newtype TypeSolution = TypeSolution { runTypeSolution :: (Int -> Type, Int -> Row) }
63−
64−emptyTypeSolution :: TypeSolution
65−emptyTypeSolution = TypeSolution (TUnknown, RUnknown)
66−
67−isFunction :: Value -> Bool
68−isFunction (Abs _ _) = True
69−isFunction (TypedValue untyped _) = isFunction untyped
70−isFunction _ = False
71−
72−allConstraints :: Ident -> Value -> Check ([TypeConstraint], Int)
73−allConstraints name val | isFunction val = do
74− me <- fresh
75− (cs, n) <- typeConstraints (M.singleton name me) val
76− return (TypeConstraint me (TUnknown n) (ValueOrigin val): cs, n)
77−allConstraints _ val = typeConstraints M.empty val
78−
79−typeOf :: Ident -> Value -> Check Type
80−typeOf name val = do
81− (cs, n) <- allConstraints name val
82− desugared <- replaceAllTypeSynonyms cs
83− solution <- solveTypeConstraints desugared emptyTypeSolution
84− let ty = fst (runTypeSolution solution) n
85− allUnknownsBecameQuantified desugared solution ty
86− return $ varIfUnknown $ desaturateAllTypeSynonyms $ setifyAll ty
87−
88−allUnknownsBecameQuantified :: [TypeConstraint] -> TypeSolution -> Type -> Check ()
89−allUnknownsBecameQuantified cs solution ty = do
90− let
91− typesMentioned = findUnknownTypes ty
92− unknownTypes = nub $ flip concatMap cs $ \c -> case c of
93− TypeConstraint u t _ -> u : findUnknownTypes t
94− RowConstraint _ r _ -> findUnknownTypes r
95− unsolvedTypes = filter (\n -> TUnknown n == fst (runTypeSolution solution) n) unknownTypes
96− guardWith "Unsolved type variable" $ null $ unsolvedTypes \\ typesMentioned
97− let
98− rowsMentioned = findUnknownRows ty
99− unknownRows = nub $ flip concatMap cs $ \c -> case c of
100− TypeConstraint _ t _ -> findUnknownRows t
101− RowConstraint u r _ -> u : findUnknownRows r
102− unsolvedRows = filter (\n -> RUnknown n == snd (runTypeSolution solution) n) unknownRows
103− guardWith "Unsolved row variable" $ null $ unsolvedRows \\ rowsMentioned
104−
105−setify :: Row -> Row
106−setify = rowFromList . first (M.toList . M.fromList) . rowToList
107−
108−setifyAll :: (D.Data d) => d -> d
109−setifyAll = everywhere (mkT setify)
110−
111−findUnknownTypes :: (D.Data d) => d -> [Int]
112−findUnknownTypes = everything (++) (mkQ [] f)
113− where
114− f :: Type -> [Int]
115− f (TUnknown n) = [n]
116− f _ = []
117−
118−findTypeVars :: (D.Data d) => d -> [String]
119−findTypeVars = everything (++) (mkQ [] f)
120− where
121− f :: Type -> [String]
122− f (TypeVar v) = [v]
123− f _ = []
124−
125−findUnknownRows :: (D.Data d) => d -> [Int]
126−findUnknownRows = everything (++) (mkQ [] f)
127− where
128− f :: Row -> [Int]
129− f (RUnknown n) = [n]
130− f _ = []
131−
132−varIfUnknown :: Type -> Type
133−varIfUnknown ty =
134− let
135− (ty', m) = flip runState M.empty $ everywhereM (flip extM g $ mkM f) ty
136− in
137− ForAll (sort $ nub $ M.elems m ++ findTypeVars ty) ty'
138− where
139− f :: Type -> State (M.Map Int String) Type
140− f (TUnknown n) = do
141− m <- get
142− case M.lookup n m of
143− Nothing -> do
144− let name = 't' : show (M.size m)
145− put $ M.insert n name m
146− return $ TypeVar name
147− Just name -> return $ TypeVar name
148− f t = return t
149− g :: Row -> State (M.Map Int String) Row
150− g (RUnknown n) = do
151− m <- get
152− case M.lookup n m of
153− Nothing -> do
154− let name = 'r' : show (M.size m)
155− put $ M.insert n name m
156− return $ RowVar name
157− Just name -> return $ RowVar name
158− g r = return r
159−
160−replaceTypeVars :: M.Map String Type -> Type -> Type
161−replaceTypeVars m = everywhere (mkT replace)
162− where
163− replace (TypeVar v) = case M.lookup v m of
164− Just ty -> ty
165− _ -> TypeVar v
166− replace t = t
167−
168−replaceVarsWithUnknowns :: [String] -> Type -> Check Type
169−replaceVarsWithUnknowns idents = flip evalStateT M.empty . everywhereM (flip extM f $ mkM g)
170− where
171− f :: Type -> StateT (M.Map String Int) Check Type
172− f (TypeVar var) | var `elem` idents = do
173− m <- get
174− n <- lift fresh
175− case M.lookup var m of
176− Nothing -> do
177− put (M.insert var n m)
178− return $ TUnknown n
179− Just u -> return $ TUnknown u
180− f t = return t
181− g :: Row -> StateT (M.Map String Int) Check Row
182− g (RowVar var) | var `elem` idents = do
183− m <- get
184− n <- lift fresh
185− case M.lookup var m of
186− Nothing -> do
187− put (M.insert var n m)
188− return $ RUnknown n
189− Just u -> return $ RUnknown u
190− g r = return r
191−
192−replaceAllTypeSynonyms :: (D.Data d) => d -> Check d
193−replaceAllTypeSynonyms d = do
194− env <- getEnv
195− let syns = map (\((path, name), (args, _)) -> (Qualified path name, length args)) . M.toList $ typeSynonyms env
196− either throwError return $ saturateAllTypeSynonyms syns d
197−
198−desaturateAllTypeSynonyms :: (D.Data d) => d -> d
199−desaturateAllTypeSynonyms = everywhere (mkT replace)
200− where
201− replace (SaturatedTypeSynonym name args) = foldl TypeApp (TypeConstructor name) args
202− replace t = t
203−
204−replaceType :: (D.Data d) => Int -> Type -> d -> d
205−replaceType n t = everywhere (mkT go)
206− where
207− go (TUnknown m) | m == n = t
208− go t = t
209−
210−replaceRow :: (D.Data d) => Int -> Row -> d -> d
211−replaceRow n r = everywhere (mkT go)
212− where
213− go (RUnknown m) | m == n = r
214− go r = r
215−
216−typeOccursCheck :: Int -> Type -> Check ()
217−typeOccursCheck u (TUnknown _) = return ()
218−typeOccursCheck u t = when (occursCheck u t) $ throwError $ "Occurs check failed: " ++ show u ++ " = " ++ prettyPrintType t
219−
220−rowOccursCheck :: Int -> Row -> Check ()
221−rowOccursCheck u (RUnknown _) = return ()
222−rowOccursCheck u r = when (occursCheck u r) $ throwError $ "Occurs check failed: " ++ show u ++ " = " ++ prettyPrintRow r
223−
224−occursCheck :: (D.Data d) => Int -> d -> Bool
225−occursCheck u = everything (||) $ flip extQ g $ mkQ False f
226− where
227− f (TUnknown u') | u' == u = True
228− f _ = False
229− g (RUnknown u') | u' == u = True
230− g _ = False
231−
232−ensureNoDuplicateProperties :: [(String, Value)] -> Check ()
233−ensureNoDuplicateProperties ps = guardWith "Duplicate property names" $ length (nub . map fst $ ps) == length ps
234−
235−typeConstraints :: M.Map Ident Int -> Value -> Check ([TypeConstraint], Int)
236−typeConstraints _ v@(NumericLiteral _) = do
237− me <- fresh
238− return ([TypeConstraint me Number (ValueOrigin v)], me)
239−typeConstraints _ v@(StringLiteral _) = do
240− me <- fresh
241− return ([TypeConstraint me String (ValueOrigin v)], me)
242−typeConstraints _ v@(BooleanLiteral _) = do
243− me <- fresh
244− return ([TypeConstraint me Boolean (ValueOrigin v)], me)
245−typeConstraints m v@(ArrayLiteral vals) = do
246− all <- mapM (typeConstraints m) vals
247− let (cs, ns) = (concatMap fst &&& map snd) all
248− me <- fresh
249− return (cs ++ zipWith (\n el -> TypeConstraint me (Array $ TUnknown n) (ValueOrigin el)) ns vals, me)
250−typeConstraints m u@(Unary op val) = do
251− (cs, n1) <- typeConstraints m val
252− me <- fresh
253− return (cs ++ unaryOperatorConstraints u op n1 me, me)
254−typeConstraints m b@(Binary op left right) = do
255− (cs1, n1) <- typeConstraints m left
256− (cs2, n2) <- typeConstraints m right
257− me <- fresh
258− return (cs1 ++ cs2 ++ binaryOperatorConstraints b op n1 n2 me, me)
259−typeConstraints m v@(ObjectLiteral ps) = do
260− ensureNoDuplicateProperties ps
261− all <- mapM (typeConstraints m . snd) ps
262− let (cs, ns) = (concatMap fst &&& map snd) all
263− me <- fresh
264− let tys = zipWith (\(name, _) u -> (name, TUnknown u)) ps ns
265− return (TypeConstraint me (Object (typesToRow tys)) (ValueOrigin v) : cs, me)
266−typeConstraints m v@(ObjectUpdate o ps) = do
267− ensureNoDuplicateProperties ps
268− (cs1, n1) <- typeConstraints m o
269− all <- mapM (typeConstraints m . snd) ps
270− let (cs2, ns) = (concatMap fst &&& map snd) all
271− row <- fresh
272− let tys = zipWith (\(name, _) u -> (name, TUnknown u)) ps ns
273− return (TypeConstraint n1 (Object (rowFromList (tys, RUnknown row))) (ValueOrigin v) : cs1 ++ cs2, n1)
274−typeConstraints m v@(Indexer index val) = do
275− (cs1, n1) <- typeConstraints m index
276− (cs2, n2) <- typeConstraints m val
277− me <- fresh
278− return (TypeConstraint n1 Number (ValueOrigin index) : TypeConstraint n2 (Array (TUnknown me)) (ValueOrigin v) : cs1 ++ cs2, me)
279−typeConstraints m v@(Accessor prop val) = do
280− (cs, n1) <- typeConstraints m val
281− me <- fresh
282− rest <- fresh
283− return (TypeConstraint n1 (Object (RCons prop (TUnknown me) (RUnknown rest))) (ValueOrigin v) : cs, me)
284−typeConstraints m v@(Abs args ret) = do
285− ns <- replicateM (length args) fresh
286− let m' = m `M.union` M.fromList (zip args ns)
287− (cs, n') <- typeConstraints m' ret
288− me <- fresh
289− return (TypeConstraint me (Function (map TUnknown ns) (TUnknown n')) (ValueOrigin v) : cs, me)
290−typeConstraints m v@(App f xs) = do
291− (cs1, n1) <- typeConstraints m f
292− all <- mapM (typeConstraints m) xs
293− let (cs2, ns) = (concatMap fst &&& map snd) all
294− me <- fresh
295− return (TypeConstraint n1 (Function (map TUnknown ns) (TUnknown me)) (ValueOrigin v) : cs1 ++ cs2, me)
296−typeConstraints m v@(Var var@(Qualified mp name)) = do
297− case mp of
298− ModulePath [] ->
299− case M.lookup name m of
300− Just u -> do
301− me <- fresh
302− return ([TypeConstraint u (TUnknown me) (ValueOrigin v)], me)
303− Nothing -> lookupGlobal
304− _ -> lookupGlobal
305− where
306− lookupGlobal = do
307− env <- getEnv
308− modulePath <- checkModulePath `fmap` get
309− case M.lookup (qualify modulePath var) (names env) of
310− Nothing -> throwError $ show var ++ " is undefined"
311− Just (ForAll idents ty, _) -> do
312− me <- fresh
313− replaced <- replaceVarsWithUnknowns idents ty
314− return ([TypeConstraint me replaced (ValueOrigin v)], me)
315−typeConstraints m (Block ss) = do
316− ret <- fresh
317− (cs, allCodePathsReturn, _) <- typeConstraintsForBlock m M.empty ret ss
318− guardWith "Block is missing a return statement" allCodePathsReturn
319− return (cs, ret)
320−typeConstraints m v@(Constructor c) = do
321− env <- getEnv
322− modulePath <- checkModulePath `fmap` get
323− case M.lookup (qualify modulePath c) (dataConstructors env) of
324− Nothing -> throwError $ "Constructor " ++ show c ++ " is undefined"
325− Just (ForAll idents ty) -> do
326− me <- fresh
327− replaced <- replaceVarsWithUnknowns idents ty
328− return ([TypeConstraint me replaced (ValueOrigin v)], me)
329−typeConstraints m (Case val binders) = do
330− (cs1, n1) <- typeConstraints m val
331− ret <- fresh
332− cs2 <- typeConstraintsForBinders m n1 ret binders
333− return (cs1 ++ cs2, ret)
334−typeConstraints m v@(IfThenElse cond th el) = do
335− (cs1, n1) <- typeConstraints m cond
336− (cs2, n2) <- typeConstraints m th
337− (cs3, n3) <- typeConstraints m el
338− return (TypeConstraint n1 Boolean (ValueOrigin cond) : TypeConstraint n2 (TUnknown n3) (ValueOrigin v) : cs1 ++ cs2 ++ cs3, n2)
339−typeConstraints m v@(TypedValue val ty) = do
340− kind <- kindOf ty
341− guardWith ("Expected type of kind *, was " ++ prettyPrintKind kind) $ kind == Star
342− typeCheck m val ty
343− me <- fresh
344− return ([TypeConstraint me ty (ValueOrigin v)], me)
345−
346−typeCheck :: M.Map Ident Int -> Value -> Type -> Check ()
347−typeCheck _ _ _ = return ()
348−
349−unaryOperatorConstraints :: Value -> UnaryOperator -> Int -> Int -> [TypeConstraint]
350−unaryOperatorConstraints v Negate val result = [TypeConstraint val Number (ValueOrigin v), TypeConstraint result Number (ValueOrigin v)]
351−unaryOperatorConstraints v Not val result = [TypeConstraint val Boolean (ValueOrigin v), TypeConstraint result Boolean (ValueOrigin v)]
352−unaryOperatorConstraints v BitwiseNot val result = [TypeConstraint val Number (ValueOrigin v), TypeConstraint result Number (ValueOrigin v)]
353−
354−binaryOperatorConstraints :: Value -> BinaryOperator -> Int -> Int -> Int -> [TypeConstraint]
355−binaryOperatorConstraints v Add = symBinOpConstraints v Number
356−binaryOperatorConstraints v Subtract = symBinOpConstraints v Number
357−binaryOperatorConstraints v Multiply = symBinOpConstraints v Number
358−binaryOperatorConstraints v Divide = symBinOpConstraints v Number
359−binaryOperatorConstraints v Modulus = symBinOpConstraints v Number
360−binaryOperatorConstraints v LessThan = asymBinOpConstraints v Number Boolean
361−binaryOperatorConstraints v LessThanOrEqualTo = asymBinOpConstraints v Number Boolean
362−binaryOperatorConstraints v GreaterThan = asymBinOpConstraints v Number Boolean
363−binaryOperatorConstraints v GreaterThanOrEqualTo = asymBinOpConstraints v Number Boolean
364−binaryOperatorConstraints v BitwiseAnd = symBinOpConstraints v Number
365−binaryOperatorConstraints v BitwiseOr = symBinOpConstraints v Number
366−binaryOperatorConstraints v BitwiseXor = symBinOpConstraints v Number
367−binaryOperatorConstraints v ShiftLeft = symBinOpConstraints v Number
368−binaryOperatorConstraints v ShiftRight = symBinOpConstraints v Number
369−binaryOperatorConstraints v ZeroFillShiftRight = symBinOpConstraints v Number
370−binaryOperatorConstraints v EqualTo = equalityBinOpConstraints v
371−binaryOperatorConstraints v NotEqualTo = equalityBinOpConstraints v
372−binaryOperatorConstraints v And = symBinOpConstraints v Boolean
373−binaryOperatorConstraints v Or = symBinOpConstraints v Boolean
374−binaryOperatorConstraints v Concat = symBinOpConstraints v String
375−
376−equalityBinOpConstraints :: Value -> Int -> Int -> Int -> [TypeConstraint]
377−equalityBinOpConstraints v left right result = [TypeConstraint left (TUnknown right) (ValueOrigin v), TypeConstraint result Boolean (ValueOrigin v)]
378−
379−symBinOpConstraints :: Value -> Type -> Int -> Int -> Int -> [TypeConstraint]
380−symBinOpConstraints v ty = asymBinOpConstraints v ty ty
381−
382−asymBinOpConstraints :: Value -> Type -> Type -> Int -> Int -> Int -> [TypeConstraint]
383−asymBinOpConstraints v ty res left right result = [TypeConstraint left ty (ValueOrigin v), TypeConstraint right ty (ValueOrigin v), TypeConstraint result res (ValueOrigin v)]
384−
385−typeConstraintsForBinder :: Int -> Binder -> Check ([TypeConstraint], M.Map Ident Int)
386−typeConstraintsForBinder _ NullBinder = return ([], M.empty)
387−typeConstraintsForBinder val b@(StringBinder _) = constantBinder b val String
388−typeConstraintsForBinder val b@(NumberBinder _) = constantBinder b val Number
389−typeConstraintsForBinder val b@(BooleanBinder _) = constantBinder b val Boolean
390−typeConstraintsForBinder val b@(VarBinder name) = do
391− me <- fresh
392− return ([TypeConstraint me (TUnknown val) (BinderOrigin b)], M.singleton name me)
393−typeConstraintsForBinder val b@(NullaryBinder ctor) = do
394− env <- getEnv
395− modulePath <- checkModulePath `fmap` get
396− case M.lookup (qualify modulePath ctor) (dataConstructors env) of
397− Just (ForAll args ret) -> do
398− ret' <- replaceVarsWithUnknowns args ret
399− return ([TypeConstraint val ret' (BinderOrigin b)], M.empty)
400− _ -> throwError $ "Constructor " ++ show ctor ++ " is not defined"
401−typeConstraintsForBinder val b@(UnaryBinder ctor binder) = do
402− env <- getEnv
403− modulePath <- checkModulePath `fmap` get
404− case M.lookup (qualify modulePath ctor) (dataConstructors env) of
405− Just (ForAll idents f@(Function [_] _)) -> do
406− obj <- fresh
407− (Function [ty] ret) <- replaceVarsWithUnknowns idents f
408− (cs, m1) <- typeConstraintsForBinder obj binder
409− return (TypeConstraint val ret (BinderOrigin b) : TypeConstraint obj ty (BinderOrigin b) : cs, m1)
410− Just _ -> throwError $ show ctor ++ " is not a unary constructor"
411− _ -> throwError $ "Constructor " ++ show ctor ++ " is not defined"
412−typeConstraintsForBinder val b@(ObjectBinder props) = do
413− row <- fresh
414− rest <- fresh
415− (cs, m1) <- typeConstraintsForProperties row (RUnknown rest) props
416− return (TypeConstraint val (Object (RUnknown row)) (BinderOrigin b) : cs, m1)
417− where
418− typeConstraintsForProperties :: Int -> Row -> [(String, Binder)] -> Check ([TypeConstraint], M.Map Ident Int)
419− typeConstraintsForProperties nrow row [] = return ([RowConstraint nrow row (BinderOrigin b)], M.empty)
420− typeConstraintsForProperties nrow row ((name, binder):binders) = do
421− propTy <- fresh
422− (cs1, m1) <- typeConstraintsForBinder propTy binder
423− (cs2, m2) <- typeConstraintsForProperties nrow (RCons name (TUnknown propTy) row) binders
424− return (cs1 ++ cs2, m1 `M.union` m2)
425−typeConstraintsForBinder val b@(ArrayBinder binders rest) = do
426− el <- fresh
427− all <- mapM (typeConstraintsForBinder el) binders
428− let (cs1, m1) = (concatMap fst &&& M.unions . map snd) all
429− let arrayConstraint = TypeConstraint val (Array (TUnknown el)) (BinderOrigin b)
430− case rest of
431− Nothing -> return (arrayConstraint : cs1, m1)
432− Just binder -> do
433− (cs2, m2) <- typeConstraintsForBinder val binder
434− return (arrayConstraint : cs1 ++ cs2, m1 `M.union` m2)
435−typeConstraintsForBinder val b@(NamedBinder name binder) = do
436− me <- fresh
437− (cs, m) <- typeConstraintsForBinder val binder
438− return (TypeConstraint me (TUnknown val) (BinderOrigin b) : cs, M.insert name me m)
439−
440−typeConstraintsForGuardedBinder :: M.Map Ident Int -> Int -> Binder -> Check ([TypeConstraint], M.Map Ident Int)
441−typeConstraintsForGuardedBinder m val b@(GuardedBinder cond binder) = do
442− (cs1, m1) <- typeConstraintsForBinder val binder
443− (cs2, n) <- typeConstraints (m `M.union` m1) cond
444− return (TypeConstraint n Boolean (ValueOrigin cond) : cs1 ++ cs2, m1)
445−typeConstraintsForGuardedBinder m val b = typeConstraintsForBinder val b >>= return
446−
447−constantBinder :: Binder -> Int -> Type -> Check ([TypeConstraint], M.Map Ident Int)
448−constantBinder b val ty = return ([TypeConstraint val ty (BinderOrigin b)], M.empty)
449−
450−typeConstraintsForBinders :: M.Map Ident Int -> Int -> Int -> [(Binder, Value)] -> Check [TypeConstraint]
451−typeConstraintsForBinders _ _ _ [] = return []
452−typeConstraintsForBinders m nval ret ((binder, val):bs) = do
453− (cs1, m1) <- typeConstraintsForGuardedBinder m nval binder
454− (cs2, n2) <- typeConstraints (m `M.union` m1) val
455− cs3 <- typeConstraintsForBinders m nval ret bs
456− return (TypeConstraint n2 (TUnknown ret) (BinderOrigin binder) : cs1 ++ cs2 ++ cs3)
457−
458−assignVariable :: Ident -> M.Map Ident Int -> Check ()
459−assignVariable name m =
460− case M.lookup name m of
461− Nothing -> return ()
462− Just _ -> throwError $ "Variable with name " ++ show name ++ " already exists."
463−
464−typeConstraintsForStatement :: M.Map Ident Int -> M.Map Ident Int -> Int -> Statement -> Check ([TypeConstraint], Bool, M.Map Ident Int)
465−typeConstraintsForStatement m mass ret (VariableIntroduction name val) = do
466− assignVariable name (m `M.union` mass)
467− (cs1, n1) <- typeConstraints m val
468− return (cs1, False, M.insert name n1 mass)
469−typeConstraintsForStatement m mass ret (Assignment ident val) = do
470− (cs1, n1) <- typeConstraints m val
471− case M.lookup ident mass of
472− Nothing -> throwError $ "No local variable with name " ++ show ident
473− Just ty ->
474− return (TypeConstraint n1 (TUnknown ty) (AssignmentTargetOrigin ident) : cs1, False, mass)
475−typeConstraintsForStatement m mass ret (While val inner) = do
476− (cs1, n1) <- typeConstraints m val
477− (cs2, allCodePathsReturn, _) <- typeConstraintsForBlock m mass ret inner
478− return (TypeConstraint n1 Boolean (ValueOrigin val) : cs1 ++ cs2, allCodePathsReturn, mass)
479−typeConstraintsForStatement m mass ret (If ifst) = do
480− (cs, allCodePathsReturn) <- typeConstraintsForIfStatement m mass ret ifst
481− return (cs, allCodePathsReturn, mass)
482−typeConstraintsForStatement m mass ret (For ident start end inner) = do
483− assignVariable ident (m `M.union` mass)
484− (cs1, n1) <- typeConstraints (m `M.union` mass) start
485− (cs2, n2) <- typeConstraints (m `M.union` mass) end
486− let mass1 = M.insert ident n1 mass
487− (cs3, allCodePathsReturn, _) <- typeConstraintsForBlock (m `M.union` mass1) mass1 ret inner
488− return (TypeConstraint n1 Number (ValueOrigin start) : TypeConstraint n2 Number (ValueOrigin end) : cs1 ++ cs2 ++ cs3, allCodePathsReturn, mass)
489−typeConstraintsForStatement m mass ret (ForEach ident vals inner) = do
490− assignVariable ident (m `M.union` mass)
491− val <- fresh
492− (cs1, n1) <- typeConstraints (m `M.union` mass) vals
493− let mass1 = M.insert ident val mass
494− (cs2, allCodePathsReturn, _) <- typeConstraintsForBlock (m `M.union` mass1) mass1 ret inner
495− guardWith "Cannot return from within a foreach block" $ not allCodePathsReturn
496− return (TypeConstraint n1 (Array (TUnknown val)) (ValueOrigin vals) : cs1 ++ cs2, False, mass)
497−typeConstraintsForStatement m mass ret (Return val) = do
498− (cs1, n1) <- typeConstraints (m `M.union` mass) val
499− return (TypeConstraint n1 (TUnknown ret) (ValueOrigin val) : cs1, True, mass)
500−
501−typeConstraintsForIfStatement :: M.Map Ident Int -> M.Map Ident Int -> Int -> IfStatement -> Check ([TypeConstraint], Bool)
502−typeConstraintsForIfStatement m mass ret (IfStatement val thens Nothing) = do
503− (cs1, n1) <- typeConstraints m val
504− (cs2, _, _) <- typeConstraintsForBlock m mass ret thens
505− return (TypeConstraint n1 Boolean (ValueOrigin val) : cs1 ++ cs2, False)
506−typeConstraintsForIfStatement m mass ret (IfStatement val thens (Just elses)) = do
507− (cs1, n1) <- typeConstraints m val
508− (cs2, allCodePathsReturn1, _) <- typeConstraintsForBlock m mass ret thens
509− (cs3, allCodePathsReturn2) <- typeConstraintsForElseStatement m mass ret elses
510− return (TypeConstraint n1 Boolean (ValueOrigin val) : cs1 ++ cs2 ++ cs3, allCodePathsReturn1 && allCodePathsReturn2)
511−
512−typeConstraintsForElseStatement :: M.Map Ident Int -> M.Map Ident Int -> Int -> ElseStatement -> Check ([TypeConstraint], Bool)
513−typeConstraintsForElseStatement m mass ret (Else elses) = do
514− (cs, allCodePathsReturn, _) <- typeConstraintsForBlock m mass ret elses
515− return (cs, allCodePathsReturn)
516−typeConstraintsForElseStatement m mass ret (ElseIf ifst) = do
517− (cs, allCodePathsReturn) <- typeConstraintsForIfStatement m mass ret ifst
518− return (cs, allCodePathsReturn)
519−
520−typeConstraintsForBlock :: M.Map Ident Int -> M.Map Ident Int -> Int -> [Statement] -> Check ([TypeConstraint], Bool, M.Map Ident Int)
521−typeConstraintsForBlock _ mass _ [] = return ([], False, mass)
522−typeConstraintsForBlock m mass ret (s:ss) = do
523− (cs1, b1, mass1) <- typeConstraintsForStatement (m `M.union` mass) mass ret s
524− case (b1, ss) of
525− (True, []) -> return (cs1, True, mass1)
526− (True, _) -> throwError "Unreachable code"
527− (False, ss) -> do
528− (cs2, b2, mass2) <- typeConstraintsForBlock m mass1 ret ss
529− return (cs1 ++ cs2, b2, mass2)
530−
531−solveTypeConstraints :: [TypeConstraint] -> TypeSolution -> Check TypeSolution
532−solveTypeConstraints [] s = return s
533−solveTypeConstraints all@(TypeConstraint n t o:cs) s = do
534− (cs', s') <- rethrow (\err -> "Error in " ++ prettyPrintOrigin o ++ ": " ++ err) $ do
535− typeOccursCheck n t
536− let s' = let (f, g) = runTypeSolution s
537− in TypeSolution (replaceType n t . f, replaceType n t . g)
538− cs' <- fmap concat $ mapM (substituteTypeInConstraint n t) cs
539− return (cs', s')
540− solveTypeConstraints cs' s'
541−solveTypeConstraints (RowConstraint n r o:cs) s = do
542− (cs', s') <- rethrow (\err -> "Error in " ++ prettyPrintOrigin o ++ ": " ++ err) $ do
543− rowOccursCheck n r
544− let s' = let (f, g) = runTypeSolution s
545− in TypeSolution (replaceRow n r . f, replaceRow n r . g)
546− cs' <- fmap concat $ mapM (substituteRowInConstraint n r) cs
547− return (cs', s')
548− solveTypeConstraints cs' s'
549−
550−substituteTypeInConstraint :: Int -> Type -> TypeConstraint -> Check [TypeConstraint]
551−substituteTypeInConstraint n s (TypeConstraint m t v)
552− | n == m = unifyTypes v s t
553− | otherwise = return [TypeConstraint m (replaceType n s t) v]
554−substituteTypeInConstraint n s (RowConstraint m r v)
555− = return [RowConstraint m (replaceType n s r) v]
556−
557−substituteRowInConstraint :: Int -> Row -> TypeConstraint -> Check [TypeConstraint]
558−substituteRowInConstraint n r (TypeConstraint m t v)
559− = return [TypeConstraint m (replaceRow n r t) v]
560−substituteRowInConstraint n r (RowConstraint m r1 v)
561− | m == n = unifyRows v r r1
562− | otherwise = return [RowConstraint m (replaceRow n r r1) v]
563−
564−unifyTypes :: TypeConstraintOrigin -> Type -> Type -> Check [TypeConstraint]
565−unifyTypes _ (TUnknown u1) (TUnknown u2) | u1 == u2 = return []
566−unifyTypes o (TUnknown u) t = do
567− typeOccursCheck u t
568− return [TypeConstraint u t o]
569−unifyTypes o t (TUnknown u) = do
570− typeOccursCheck u t
571− return [TypeConstraint u t o]
572−unifyTypes o (SaturatedTypeSynonym name1 args1) (SaturatedTypeSynonym name2 args2) | name1 == name2 =
573− fmap concat $ zipWithM (unifyTypes o) args1 args2
574−unifyTypes o (SaturatedTypeSynonym name args) ty = do
575− env <- getEnv
576− modulePath <- checkModulePath `fmap` get
577− case M.lookup (qualify modulePath name) (typeSynonyms env) of
578− Just (synArgs, body) -> do
579− let m = M.fromList $ zip synArgs args
580− let replaced = replaceTypeVars m body
581− unifyTypes o replaced ty
582− Nothing -> error "Type synonym was not defined"
583−unifyTypes o ty s@(SaturatedTypeSynonym _ _) = unifyTypes o s ty
584−unifyTypes o (ForAll idents ty1) ty2 =do
585− sk <- skolemize idents ty1
586− unifyTypes o sk ty2
587−unifyTypes o ty f@(ForAll _ _) = unifyTypes o f ty
588−unifyTypes _ Number Number = return []
589−unifyTypes _ String String = return []
590−unifyTypes _ Boolean Boolean = return []
591−unifyTypes o (Array s) (Array t) = unifyTypes o s t
592−unifyTypes o (Object row1) (Object row2) = unifyRows o row1 row2
593−unifyTypes o (Function args1 ret1) (Function args2 ret2) = do
594− guardWith "Function applied to incorrect number of args" $ length args1 == length args2
595− cs1 <- fmap concat $ zipWithM (unifyTypes o) args1 args2
596− cs2 <- unifyTypes o ret1 ret2
597− return $ cs1 ++ cs2
598−unifyTypes _ (TypeVar v1) (TypeVar v2) | v1 == v2 = return []
599−unifyTypes _ (TypeConstructor c1) (TypeConstructor c2) = do
600− modulePath <- checkModulePath `fmap` get
601− guardWith ("Cannot unify " ++ show c1 ++ " with " ++ show c2 ++ ".") (qualify modulePath c1 == qualify modulePath c2)
602− return []
603−unifyTypes o (TypeApp t1 t2) (TypeApp t3 t4) = do
604− cs1 <- unifyTypes o t1 t3
605− cs2 <- unifyTypes o t2 t4
606− return $ cs1 ++ cs2
607−unifyTypes _ (Skolem s1) (Skolem s2) | s1 == s2 = return []
608−unifyTypes _ t1 t2 = throwError $ "Cannot unify " ++ prettyPrintType t1 ++ " with " ++ prettyPrintType t2 ++ "."
609−
610−unifyRows :: TypeConstraintOrigin -> Row -> Row -> Check [TypeConstraint]
611−unifyRows o r1 r2 =
612− let
613− (s1, r1') = rowToList r1
614− (s2, r2') = rowToList r2
615− int = [ (t1, t2) | (name, t1) <- s1, (name', t2) <- s2, name == name' ]
616− sd1 = [ (name, t1) | (name, t1) <- s1, name `notElem` map fst s2 ]
617− sd2 = [ (name, t2) | (name, t2) <- s2, name `notElem` map fst s1 ]
618− in do
619− cs1 <- fmap concat $ mapM (uncurry $ unifyTypes o) int
620− cs2 <- unifyRows' o sd1 r1' sd2 r2'
621− return $ cs1 ++ cs2
622− where
623− unifyRows' :: TypeConstraintOrigin -> [(String, Type)] -> Row -> [(String, Type)] -> Row -> Check [TypeConstraint]
624− unifyRows' o [] (RUnknown u) sd r = do
625− rowOccursCheck u r
626− return [RowConstraint u (rowFromList (sd, r)) o]
627− unifyRows' o sd r [] (RUnknown u) = do
628− rowOccursCheck u r
629− return [RowConstraint u (rowFromList (sd, r)) o]
630− unifyRows' o ns@((name, ty):row) r others (RUnknown u) | not (occursCheck u (ty, row)) = do
631− u' <- fresh
632− cs <- unifyRows' o row r others (RUnknown u')
633− return (RowConstraint u (RCons name ty (RUnknown u')) o : cs)
634− unifyRows' _ [] REmpty [] REmpty = return []
635− unifyRows' _ [] (RowVar v1) [] (RowVar v2) | v1 == v2 = return []
636− unifyRows' _ sd1 r1 sd2 r2 = throwError $ "Cannot unify " ++ prettyPrintRow (rowFromList (sd1, r1)) ++ " with " ++ prettyPrintRow (rowFromList (sd2, r2)) ++ "."
637−
638−skolemize :: [String] -> Type -> Check Type
639−skolemize idents ty = do
640− sks <- replicateM (length idents) fresh
641− let m = M.fromList (zip idents (map Skolem sks))
642− return $ replaceTypeVars m ty
643−