@@ -1,627 +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 PolyType
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 -> PolyType
133−varIfUnknown ty =
134− let
135− (ty', m) = flip runState M.empty $ everywhereM (flip extM g $ mkM f) ty
136− in
137− PolyType (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 (\(name, (args, _)) -> (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−typesToRow :: [(String, Type)] -> Row
233−typesToRow [] = REmpty
234−typesToRow ((name, ty):tys) = RCons name ty (typesToRow tys)
235−
236−rowToList :: Row -> ([(String, Type)], Row)
237−rowToList (RCons name ty row) = let (tys, rest) = rowToList row
238− in ((name, ty):tys, rest)
239−rowToList r = ([], r)
240−
241−rowFromList :: ([(String, Type)], Row) -> Row
242−rowFromList ([], r) = r
243−rowFromList ((name, t):ts, r) = RCons name t (rowFromList (ts, r))
244−
245−ensureNoDuplicateProperties :: [(String, Value)] -> Check ()
246−ensureNoDuplicateProperties ps = guardWith "Duplicate property names" $ length (nub . map fst $ ps) == length ps
247−
248−typeConstraints :: M.Map Ident Int -> Value -> Check ([TypeConstraint], Int)
249−typeConstraints _ v@(NumericLiteral _) = do
250− me <- fresh
251− return ([TypeConstraint me Number (ValueOrigin v)], me)
252−typeConstraints _ v@(StringLiteral _) = do
253− me <- fresh
254− return ([TypeConstraint me String (ValueOrigin v)], me)
255−typeConstraints _ v@(BooleanLiteral _) = do
256− me <- fresh
257− return ([TypeConstraint me Boolean (ValueOrigin v)], me)
258−typeConstraints m v@(ArrayLiteral vals) = do
259− all <- mapM (typeConstraints m) vals
260− let (cs, ns) = (concatMap fst &&& map snd) all
261− me <- fresh
262− return (cs ++ zipWith (\n el -> TypeConstraint me (Array $ TUnknown n) (ValueOrigin el)) ns vals, me)
263−typeConstraints m u@(Unary op val) = do
264− (cs, n1) <- typeConstraints m val
265− me <- fresh
266− return (cs ++ unaryOperatorConstraints u op n1 me, me)
267−typeConstraints m b@(Binary op left right) = do
268− (cs1, n1) <- typeConstraints m left
269− (cs2, n2) <- typeConstraints m right
270− me <- fresh
271− return (cs1 ++ cs2 ++ binaryOperatorConstraints b op n1 n2 me, me)
272−typeConstraints m v@(ObjectLiteral ps) = do
273− ensureNoDuplicateProperties ps
274− all <- mapM (typeConstraints m . snd) ps
275− let (cs, ns) = (concatMap fst &&& map snd) all
276− me <- fresh
277− let tys = zipWith (\(name, _) u -> (name, TUnknown u)) ps ns
278− return (TypeConstraint me (Object (typesToRow tys)) (ValueOrigin v) : cs, me)
279−typeConstraints m v@(ObjectUpdate o ps) = do
280− ensureNoDuplicateProperties ps
281− (cs1, n1) <- typeConstraints m o
282− all <- mapM (typeConstraints m . snd) ps
283− let (cs2, ns) = (concatMap fst &&& map snd) all
284− row <- fresh
285− let tys = zipWith (\(name, _) u -> (name, TUnknown u)) ps ns
286− return (TypeConstraint n1 (Object (rowFromList (tys, RUnknown row))) (ValueOrigin v) : cs1 ++ cs2, n1)
287−typeConstraints m v@(Indexer index val) = do
288− (cs1, n1) <- typeConstraints m index
289− (cs2, n2) <- typeConstraints m val
290− me <- fresh
291− return (TypeConstraint n1 Number (ValueOrigin index) : TypeConstraint n2 (Array (TUnknown me)) (ValueOrigin v) : cs1 ++ cs2, me)
292−typeConstraints m v@(Accessor prop val) = do
293− (cs, n1) <- typeConstraints m val
294− me <- fresh
295− rest <- fresh
296− return (TypeConstraint n1 (Object (RCons prop (TUnknown me) (RUnknown rest))) (ValueOrigin v) : cs, me)
297−typeConstraints m v@(Abs args ret) = do
298− ns <- replicateM (length args) fresh
299− let m' = m `M.union` M.fromList (zip args ns)
300− (cs, n') <- typeConstraints m' ret
301− me <- fresh
302− return (TypeConstraint me (Function (map TUnknown ns) (TUnknown n')) (ValueOrigin v) : cs, me)
303−typeConstraints m v@(App f xs) = do
304− (cs1, n1) <- typeConstraints m f
305− all <- mapM (typeConstraints m) xs
306− let (cs2, ns) = (concatMap fst &&& map snd) all
307− me <- fresh
308− return (TypeConstraint n1 (Function (map TUnknown ns) (TUnknown me)) (ValueOrigin v) : cs1 ++ cs2, me)
309−typeConstraints m v@(Var var) =
310− case M.lookup var m of
311− Nothing -> do
312− env <- getEnv
313− case M.lookup var (names env) of
314− Nothing -> throwError $ show var ++ " is undefined"
315− Just (PolyType idents ty, _) -> do
316− me <- fresh
317− replaced <- replaceVarsWithUnknowns idents ty
318− return ([TypeConstraint me replaced (ValueOrigin v)], me)
319− Just u -> do
320− me <- fresh
321− return ([TypeConstraint u (TUnknown me) (ValueOrigin v)], me)
322−typeConstraints m (Block ss) = do
323− ret <- fresh
324− (cs, allCodePathsReturn, _) <- typeConstraintsForBlock m M.empty ret ss
325− guardWith "Block is missing a return statement" allCodePathsReturn
326− return (cs, ret)
327−typeConstraints m v@(Constructor c) = do
328− env <- getEnv
329− case M.lookup c (dataConstructors env) of
330− Nothing -> throwError $ "Constructor " ++ c ++ " is undefined"
331− Just (PolyType idents ty) -> do
332− me <- fresh
333− replaced <- replaceVarsWithUnknowns idents ty
334− return ([TypeConstraint me replaced (ValueOrigin v)], me)
335−typeConstraints m (Case val binders) = do
336− (cs1, n1) <- typeConstraints m val
337− ret <- fresh
338− cs2 <- typeConstraintsForBinders m n1 ret binders
339− return (cs1 ++ cs2, ret)
340−typeConstraints m v@(IfThenElse cond th el) = do
341− (cs1, n1) <- typeConstraints m cond
342− (cs2, n2) <- typeConstraints m th
343− (cs3, n3) <- typeConstraints m el
344− return (TypeConstraint n1 Boolean (ValueOrigin cond) : TypeConstraint n2 (TUnknown n3) (ValueOrigin v) : cs1 ++ cs2 ++ cs3, n2)
345−typeConstraints m v@(TypedValue val poly@(PolyType idents ty)) = do
346− kind <- kindOf poly
347− guardWith ("Expected type of kind *, was " ++ prettyPrintKind kind) $ kind == Star
348− (cs, n1) <- typeConstraints m val
349− return (TypeConstraint n1 ty (ValueOrigin v) : cs, n1)
350−
351−unaryOperatorConstraints :: Value -> UnaryOperator -> Int -> Int -> [TypeConstraint]
352−unaryOperatorConstraints v Negate val result = [TypeConstraint val Number (ValueOrigin v), TypeConstraint result Number (ValueOrigin v)]
353−unaryOperatorConstraints v Not val result = [TypeConstraint val Boolean (ValueOrigin v), TypeConstraint result Boolean (ValueOrigin v)]
354−unaryOperatorConstraints v BitwiseNot val result = [TypeConstraint val Number (ValueOrigin v), TypeConstraint result Number (ValueOrigin v)]
355−
356−binaryOperatorConstraints :: Value -> BinaryOperator -> Int -> Int -> Int -> [TypeConstraint]
357−binaryOperatorConstraints v Add = symBinOpConstraints v Number
358−binaryOperatorConstraints v Subtract = symBinOpConstraints v Number
359−binaryOperatorConstraints v Multiply = symBinOpConstraints v Number
360−binaryOperatorConstraints v Divide = symBinOpConstraints v Number
361−binaryOperatorConstraints v Modulus = symBinOpConstraints v Number
362−binaryOperatorConstraints v LessThan = asymBinOpConstraints v Number Boolean
363−binaryOperatorConstraints v LessThanOrEqualTo = asymBinOpConstraints v Number Boolean
364−binaryOperatorConstraints v GreaterThan = asymBinOpConstraints v Number Boolean
365−binaryOperatorConstraints v GreaterThanOrEqualTo = asymBinOpConstraints v Number Boolean
366−binaryOperatorConstraints v BitwiseAnd = symBinOpConstraints v Number
367−binaryOperatorConstraints v BitwiseOr = symBinOpConstraints v Number
368−binaryOperatorConstraints v BitwiseXor = symBinOpConstraints v Number
369−binaryOperatorConstraints v ShiftLeft = symBinOpConstraints v Number
370−binaryOperatorConstraints v ShiftRight = symBinOpConstraints v Number
371−binaryOperatorConstraints v ZeroFillShiftRight = symBinOpConstraints v Number
372−binaryOperatorConstraints v EqualTo = equalityBinOpConstraints v
373−binaryOperatorConstraints v NotEqualTo = equalityBinOpConstraints v
374−binaryOperatorConstraints v And = symBinOpConstraints v Boolean
375−binaryOperatorConstraints v Or = symBinOpConstraints v Boolean
376−binaryOperatorConstraints v Concat = symBinOpConstraints v String
377−
378−equalityBinOpConstraints :: Value -> Int -> Int -> Int -> [TypeConstraint]
379−equalityBinOpConstraints v left right result = [TypeConstraint left (TUnknown right) (ValueOrigin v), TypeConstraint result Boolean (ValueOrigin v)]
380−
381−symBinOpConstraints :: Value -> Type -> Int -> Int -> Int -> [TypeConstraint]
382−symBinOpConstraints v ty = asymBinOpConstraints v ty ty
383−
384−asymBinOpConstraints :: Value -> Type -> Type -> Int -> Int -> Int -> [TypeConstraint]
385−asymBinOpConstraints v ty res left right result = [TypeConstraint left ty (ValueOrigin v), TypeConstraint right ty (ValueOrigin v), TypeConstraint result res (ValueOrigin v)]
386−
387−typeConstraintsForBinder :: Int -> Binder -> Check ([TypeConstraint], M.Map Ident Int)
388−typeConstraintsForBinder _ NullBinder = return ([], M.empty)
389−typeConstraintsForBinder val b@(StringBinder _) = constantBinder b val String
390−typeConstraintsForBinder val b@(NumberBinder _) = constantBinder b val Number
391−typeConstraintsForBinder val b@(BooleanBinder _) = constantBinder b val Boolean
392−typeConstraintsForBinder val b@(VarBinder name) = do
393− me <- fresh
394− return ([TypeConstraint me (TUnknown val) (BinderOrigin b)], M.singleton name me)
395−typeConstraintsForBinder val b@(NullaryBinder ctor) = do
396− env <- getEnv
397− case M.lookup ctor (dataConstructors env) of
398− Just (PolyType args ret) -> do
399− ret' <- replaceVarsWithUnknowns args ret
400− return ([TypeConstraint val ret' (BinderOrigin b)], M.empty)
401− _ -> throwError $ "Constructor " ++ ctor ++ " is not defined"
402−typeConstraintsForBinder val b@(UnaryBinder ctor binder) = do
403− env <- getEnv
404− case M.lookup ctor (dataConstructors env) of
405− Just (PolyType 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 $ ctor ++ " is not a unary constructor"
411− _ -> throwError $ "Constructor " ++ 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− case M.lookup name (typeSynonyms env) of
577− Just (synArgs, body) -> do
578− let m = M.fromList $ zip synArgs args
579− let replaced = replaceTypeVars m body
580− unifyTypes o replaced ty
581− Nothing -> error "Type synonym was not defined"
582−unifyTypes o ty s@(SaturatedTypeSynonym _ _) = unifyTypes o s ty
583−unifyTypes _ Number Number = return []
584−unifyTypes _ String String = return []
585−unifyTypes _ Boolean Boolean = return []
586−unifyTypes o (Array s) (Array t) = unifyTypes o s t
587−unifyTypes o (Object row1) (Object row2) = unifyRows o row1 row2
588−unifyTypes o (Function args1 ret1) (Function args2 ret2) = do
589− guardWith "Function applied to incorrect number of args" $ length args1 == length args2
590− cs1 <- fmap concat $ zipWithM (unifyTypes o) args1 args2
591− cs2 <- unifyTypes o ret1 ret2
592− return $ cs1 ++ cs2
593−unifyTypes _ (TypeVar v1) (TypeVar v2) | v1 == v2 = return []
594−unifyTypes _ (TypeConstructor c1) (TypeConstructor c2) | c1 == c2 = return []
595−unifyTypes o (TypeApp t1 t2) (TypeApp t3 t4) = do
596− cs1 <- unifyTypes o t1 t3
597− cs2 <- unifyTypes o t2 t4
598− return $ cs1 ++ cs2
599−unifyTypes _ t1 t2 = throwError $ "Cannot unify " ++ prettyPrintType t1 ++ " with " ++ prettyPrintType t2 ++ "."
600−
601−unifyRows :: TypeConstraintOrigin -> Row -> Row -> Check [TypeConstraint]
602−unifyRows o r1 r2 =
603− let
604− (s1, r1') = rowToList r1
605− (s2, r2') = rowToList r2
606− int = [ (t1, t2) | (name, t1) <- s1, (name', t2) <- s2, name == name' ]
607− sd1 = [ (name, t1) | (name, t1) <- s1, name `notElem` map fst s2 ]
608− sd2 = [ (name, t2) | (name, t2) <- s2, name `notElem` map fst s1 ]
609− in do
610− cs1 <- fmap concat $ mapM (uncurry $ unifyTypes o) int
611− cs2 <- unifyRows' o sd1 r1' sd2 r2'
612− return $ cs1 ++ cs2
613− where
614− unifyRows' :: TypeConstraintOrigin -> [(String, Type)] -> Row -> [(String, Type)] -> Row -> Check [TypeConstraint]
615− unifyRows' o [] (RUnknown u) sd r = do
616− rowOccursCheck u r
617− return [RowConstraint u (rowFromList (sd, r)) o]
618− unifyRows' o sd r [] (RUnknown u) = do
619− rowOccursCheck u r
620− return [RowConstraint u (rowFromList (sd, r)) o]
621− unifyRows' o ns@((name, ty):row) r others (RUnknown u) | not (occursCheck u (ty, row)) = do
622− u' <- fresh
623− cs <- unifyRows' o row r others (RUnknown u')
624− return (RowConstraint u (RCons name ty (RUnknown u')) o : cs)
625− unifyRows' _ [] REmpty [] REmpty = return []
626− unifyRows' _ [] (RowVar v1) [] (RowVar v2) | v1 == v2 = return []
627− unifyRows' _ sd1 r1 sd2 r2 = throwError $ "Cannot unify " ++ prettyPrintRow (rowFromList (sd1, r1)) ++ " with " ++ prettyPrintRow (rowFromList (sd2, r2)) ++ "."