1-----------------------------------------------------------------------------
3-- Module : Language.PureScript.TypeChecker
4-- Copyright : (c) Phil Freeman 2013
7-- Maintainer : Phil Freeman <paf31@cantab.net>
8-- Stability : experimental
12-- The top-level type checker, which checks all declarations in a module.
14-----------------------------------------------------------------------------
16{-# LANGUAGE FlexibleInstances #-}
18module Language.PureScript.TypeChecker (
23import Language.PureScript.TypeChecker.Monad as T
24import Language.PureScript.TypeChecker.Kinds as T
25import Language.PureScript.TypeChecker.Types as T
26import Language.PureScript.TypeChecker.Synonyms as T
29import qualified Data.Map as M
30import Control.Monad.State
31import Control.Monad.Error
32import Data.Either (rights, lefts)
34import Language.PureScript.Types
35import Language.PureScript.Names
36import Language.PureScript.Values
37import Language.PureScript.Kinds
38import Language.PureScript.Declarations
39import Language.PureScript.Sugar.TypeClasses
41addDataType :: ModuleName -> ProperName -> [String] -> [(ProperName, Maybe Type)] -> Kind -> Check ()
42addDataType moduleName name args dctors ctorKind = do
44 putEnv $ env { types = M.insert (moduleName, name) (ctorKind, Data) (types env) }
45 forM_ dctors $ \(dctor, maybeTy) ->
46 rethrow (("Error in data constructor " ++ show dctor ++ ":\n") ++) $
47 addDataConstructor moduleName name args dctor maybeTy
49addDataConstructor :: ModuleName -> ProperName -> [String] -> ProperName -> Maybe Type -> Check ()
50addDataConstructor moduleName name args dctor maybeTy = do
52 dataConstructorIsNotDefined moduleName dctor
53 when (runModuleName moduleName == dctor) $ throwError "A data constructor may not have the same name as its enclosing module."
54 let retTy = foldl TypeApp (TypeConstructor (Qualified (Just moduleName) name)) (map TypeVar args)
55 let dctorTy = maybe retTy (flip function retTy) maybeTy
56 let polyType = mkForAll args dctorTy
57 putEnv $ env { dataConstructors = M.insert (moduleName, dctor) (qualifyAllUnqualifiedNames moduleName env polyType, DataConstructor) (dataConstructors env) }
59addTypeSynonym :: ModuleName -> ProperName -> [String] -> Type -> Kind -> Check ()
60addTypeSynonym moduleName name args ty kind = do
62 putEnv $ env { types = M.insert (moduleName, name) (kind, TypeSynonym) (types env)
63 , typeSynonyms = M.insert (moduleName, name) (args, qualifyAllUnqualifiedNames moduleName env ty) (typeSynonyms env) }
65typeIsNotDefined :: ModuleName -> ProperName -> Check ()
66typeIsNotDefined moduleName name = do
68 guardWith (show name ++ " is already defined") $
69 not $ M.member (moduleName, name) (types env)
71dataConstructorIsNotDefined :: ModuleName -> ProperName -> Check ()
72dataConstructorIsNotDefined moduleName dctor = do
74 guardWith (show dctor ++ " is already defined") $
75 not $ M.member (moduleName, dctor) (dataConstructors env)
77valueIsNotDefined :: ModuleName -> Ident -> Check ()
78valueIsNotDefined moduleName name = do
80 case M.lookup (moduleName, name) (names env) of
81 Just _ -> throwError $ show name ++ " is already defined"
84addValue :: ModuleName -> Ident -> Type -> Check ()
85addValue moduleName name ty = do
87 putEnv (env { names = M.insert (moduleName, name) (qualifyAllUnqualifiedNames moduleName env ty, Value) (names env) })
89addTypeClassDictionaries :: [TypeClassDictionaryInScope] -> Check ()
90addTypeClassDictionaries entries = do
91 modify $ \st -> st { checkEnv = (checkEnv st) { typeClassDictionaries = entries ++ (typeClassDictionaries . checkEnv $ st) } }
93checkTypeClassInstance :: ModuleName -> Type -> Check ()
94checkTypeClassInstance _ (TypeVar _) = return ()
95checkTypeClassInstance m (TypeConstructor ctor) = do
97 when (canonicalizeType m env ctor `M.member` typeSynonyms env) $ throwError "Type synonym instances are disallowed"
99checkTypeClassInstance m (TypeApp ty (TypeVar _)) = checkTypeClassInstance m ty
100checkTypeClassInstance _ _ = throwError "Type class instance must be of the form T a1 ... an"
103-- Type check all declarations in a module
105-- At this point, many declarations will have been desugared, but it is still necessary to
107-- * Kind-check all types and add them to the @Environment@
109-- * Type-check all values and add them to the @Environment@
111-- * Bring type class instances into scope
113-- * Process module imports
115typeCheckAll :: ModuleName -> [Declaration] -> Check [Declaration]
116typeCheckAll _ [] = return []
117typeCheckAll moduleName (d@(DataDeclaration name args dctors) : rest) = do
118 rethrow (("Error in type constructor " ++ show name ++ ":\n") ++) $ do
119 typeIsNotDefined moduleName name
120 ctorKind <- kindsOf moduleName name args (mapMaybe snd dctors)
121 addDataType moduleName name args dctors ctorKind
122 ds <- typeCheckAll moduleName rest
124typeCheckAll moduleName (d@(DataBindingGroupDeclaration tys) : rest) = do
125 rethrow ("Error in data binding group:\n" ++) $ do
126 let syns = mapMaybe toTypeSynonym tys
127 let dataDecls = mapMaybe toDataDecl tys
128 (syn_ks, data_ks) <- kindsOfAll moduleName syns (map (\(name, args, dctors) -> (name, args, mapMaybe snd dctors)) dataDecls)
129 forM_ (zip dataDecls data_ks) $ \((name, args, dctors), ctorKind) -> do
130 typeIsNotDefined moduleName name
131 addDataType moduleName name args dctors ctorKind
132 forM_ (zip syns syn_ks) $ \((name, args, ty), kind) -> do
133 typeIsNotDefined moduleName name
134 addTypeSynonym moduleName name args ty kind
135 ds <- typeCheckAll moduleName rest
138 toTypeSynonym (TypeSynonymDeclaration nm args ty) = Just (nm, args, ty)
139 toTypeSynonym _ = Nothing
140 toDataDecl (DataDeclaration nm args dctors) = Just (nm, args, dctors)
141 toDataDecl _ = Nothing
142typeCheckAll moduleName (d@(TypeSynonymDeclaration name args ty) : rest) = do
143 rethrow (("Error in type synonym " ++ show name ++ ":\n") ++) $ do
144 typeIsNotDefined moduleName name
145 kind <- kindsOf moduleName name args [ty]
146 addTypeSynonym moduleName name args ty kind
147 ds <- typeCheckAll moduleName rest
149typeCheckAll _ (TypeDeclaration _ _ : _) = error "Type declarations should have been removed"
150typeCheckAll moduleName (ValueDeclaration name [] Nothing val : rest) = do
151 d <- rethrow (("Error in declaration " ++ show name ++ ":\n") ++) $ do
152 valueIsNotDefined moduleName name
153 [(_, (val', ty))] <- typesOf moduleName [(name, val)]
154 addValue moduleName name ty
155 return $ ValueDeclaration name [] Nothing val'
156 ds <- typeCheckAll moduleName rest
158typeCheckAll _ (ValueDeclaration _ _ _ _ : _) = error "Binders were not desugared"
159typeCheckAll moduleName (BindingGroupDeclaration vals : rest) = do
160 d <- rethrow (("Error in binding group " ++ show (map fst vals) ++ ":\n") ++) $ do
161 forM_ (map fst vals) $ \name ->
162 valueIsNotDefined moduleName name
163 tys <- typesOf moduleName vals
164 vals' <- forM (zip (map fst vals) (map snd tys)) $ \(name, (val, ty)) -> do
165 addValue moduleName name ty
167 return $ BindingGroupDeclaration vals'
168 ds <- typeCheckAll moduleName rest
170typeCheckAll moduleName (d@(ExternDataDeclaration name kind) : rest) = do
172 guardWith (show name ++ " is already defined") $ not $ M.member (moduleName, name) (types env)
173 putEnv $ env { types = M.insert (moduleName, name) (kind, TypeSynonym) (types env) }
174 ds <- typeCheckAll moduleName rest
176typeCheckAll moduleName (d@(ExternDeclaration importTy name _ ty) : rest) = do
177 rethrow (("Error in foreign import declaration " ++ show name ++ ":\n") ++) $ do
179 kind <- kindOf moduleName ty
180 guardWith "Expected kind *" $ kind == Star
181 case M.lookup (moduleName, name) (names env) of
182 Just _ -> throwError $ show name ++ " is already defined"
183 Nothing -> putEnv (env { names = M.insert (moduleName, name) (qualifyAllUnqualifiedNames moduleName env ty, Extern importTy) (names env) })
184 ds <- typeCheckAll moduleName rest
186typeCheckAll moduleName (d@(FixityDeclaration _ name) : rest) = do
187 ds <- typeCheckAll moduleName rest
189 guardWith ("Fixity declaration with no binding: " ++ name) $ M.member (moduleName, Op name) $ names env
191typeCheckAll currentModule (d@(ImportDeclaration moduleName idents) : rest) = do
193 rethrow errorMessage $ do
194 guardWith ("Module " ++ show moduleName ++ " does not exist") $ moduleExists env
197 shadowIdents (map snd $ filterModule (names env)) env
198 shadowTypes (map snd $ filterModule (types env)) env
200 shadowIdents (lefts idents') env
201 shadowTypes (rights idents') env
202 shadowTypeClassInstances env
203 ds <- typeCheckAll currentModule rest
206 errorMessage = (("Error in import declaration " ++ show moduleName ++ ":\n") ++)
207 filterModule = filter ((== moduleName) . fst) . M.keys
208 moduleExists env = not (null (filterModule (names env))) || not (null (filterModule (types env)))
209 shadowIdents idents' env =
210 forM_ idents' $ \ident -> do
211 case (moduleName, ident) `M.lookup` names env of
212 Just (_, Alias _ _) -> return ()
214 guardWith (show currentModule ++ "." ++ show ident ++ " is already defined") $ (currentModule, ident) `M.notMember` names env
215 modifyEnv (\e -> e { names = M.insert (currentModule, ident) (pt, Alias moduleName ident) (names e) })
216 Nothing -> throwError (show moduleName ++ "." ++ show ident ++ " is undefined")
217 shadowTypes pns env =
218 forM_ pns $ \pn -> do
219 case (moduleName, pn) `M.lookup` types env of
220 Nothing -> throwError (show moduleName ++ "." ++ show pn ++ " is undefined")
221 Just (_, DataAlias _ _) -> return ()
223 guardWith (show currentModule ++ "." ++ show pn ++ " is already defined") $ (currentModule, pn) `M.notMember` types env
224 modifyEnv (\e -> e { types = M.insert (currentModule, pn) (k, DataAlias moduleName pn) (types e) })
225 let keys = map (snd . fst) . filter (\(_, (fn, _)) -> fn `constructs` pn) . M.toList . dataConstructors $ env
226 forM_ keys $ \dctor -> do
227 case (moduleName, dctor) `M.lookup` dataConstructors env of
228 Just (_, Alias _ _) -> return ()
229 Just (ctorTy, _) -> do
230 guardWith (show currentModule ++ "." ++ show dctor ++ " is already defined") $ (currentModule, dctor) `M.notMember` dataConstructors env
231 modifyEnv (\e -> e { dataConstructors = M.insert (currentModule, dctor) (ctorTy, Alias moduleName (Ident (runProperName dctor))) (dataConstructors e) })
232 Nothing -> throwError (show moduleName ++ "." ++ show dctor ++ " is undefined")
233 shadowTypeClassInstances env = do
234 let instances = filter (\tcd ->
235 let Qualified (Just mn) _ = tcdName tcd in
236 moduleName == mn && tcdType tcd == TCDRegular
237 ) (typeClassDictionaries env)
238 forM_ instances $ \tcd -> do
239 let (Qualified _ ident) = tcdName tcd
240 addTypeClassDictionaries [tcd { tcdName = (Qualified (Just currentModule) ident), tcdType = TCDAlias (tcdName tcd) }]
241 constructs (TypeConstructor (Qualified (Just mn) pn')) pn
242 = mn == moduleName && pn' == pn
243 constructs (ForAll _ ty _) pn = ty `constructs` pn
244 constructs (TypeApp (TypeApp t _) ty) pn | t == tyFunction = ty `constructs` pn
245 constructs (TypeApp ty _) pn = ty `constructs` pn
246 constructs fn _ = error $ "Invalid arguments to constructs: " ++ show fn
247typeCheckAll moduleName (d@(TypeClassDeclaration _ _ _) : rest) = do
249 ds <- typeCheckAll moduleName rest
250 return $ qualifyAllUnqualifiedNames moduleName env d : ds
251typeCheckAll moduleName (d@(TypeInstanceDeclaration deps className ty _) : rest) = do
253 dictName <- Check . lift $ mkDictionaryValueName moduleName className ty
254 checkTypeClassInstance moduleName ty
255 forM_ deps $ checkTypeClassInstance moduleName . snd
256 addTypeClassDictionaries (qualifyAllUnqualifiedNames moduleName env
257 [TypeClassDictionaryInScope (Qualified (Just moduleName) dictName) className ty (Just deps) TCDRegular])
258 ds <- typeCheckAll moduleName rest
259 return $ qualifyAllUnqualifiedNames moduleName env d : ds
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