git.iko.soy/rowtype-yoga/purescript-native
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rowtype-yoga/purescript-native/src/Language/PureScript/TypeChecker.hs
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1-----------------------------------------------------------------------------
2--
3-- Module : Language.PureScript.TypeChecker
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-- The top-level type checker, which checks all declarations in a module.
13--
14-----------------------------------------------------------------------------
16{-# LANGUAGE FlexibleInstances #-}
18module Language.PureScript.TypeChecker (
19 module T,
20 typeCheckAll
21) where
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
28import Data.Maybe
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, [Type])] -> Kind -> Check ()
42addDataType moduleName name args dctors ctorKind = do
43 env <- getEnv
44 putEnv $ env { types = M.insert (Qualified (Just moduleName) name) ctorKind (types env) }
45 forM_ dctors $ \(dctor, tys) ->
46 rethrow (("Error in data constructor " ++ show dctor ++ ":\n") ++) $
47 addDataConstructor moduleName name args dctor tys
49addDataConstructor :: ModuleName -> ProperName -> [String] -> ProperName -> [Type] -> Check ()
50addDataConstructor moduleName name args dctor tys = do
51 env <- getEnv
52 let retTy = foldl TypeApp (TypeConstructor (Qualified (Just moduleName) name)) (map TypeVar args)
53 let dctorTy = foldr function retTy tys
54 let polyType = mkForAll args dctorTy
55 putEnv $ env { dataConstructors = M.insert (Qualified (Just moduleName) dctor) polyType (dataConstructors env) }
57addTypeSynonym :: ModuleName -> ProperName -> [String] -> Type -> Kind -> Check ()
58addTypeSynonym moduleName name args ty kind = do
59 env <- getEnv
60 putEnv $ env { types = M.insert (Qualified (Just moduleName) name) kind (types env)
61 , typeSynonyms = M.insert (Qualified (Just moduleName) name) (args, ty) (typeSynonyms env) }
63valueIsNotDefined :: ModuleName -> Ident -> Check ()
64valueIsNotDefined moduleName name = do
65 env <- getEnv
66 case M.lookup (moduleName, name) (names env) of
67 Just _ -> throwError $ show name ++ " is already defined"
68 Nothing -> return ()
70addValue :: ModuleName -> Ident -> Type -> Check ()
71addValue moduleName name ty = do
72 env <- getEnv
73 putEnv (env { names = M.insert (moduleName, name) (ty, Value) (names env) })
75addTypeClassDictionaries :: [TypeClassDictionaryInScope] -> Check ()
76addTypeClassDictionaries entries =
77 modify $ \st -> st { checkEnv = (checkEnv st) { typeClassDictionaries = entries ++ (typeClassDictionaries . checkEnv $ st) } }
79checkTypeClassInstance :: ModuleName -> Type -> Check ()
80checkTypeClassInstance _ (TypeVar _) = return ()
81checkTypeClassInstance m (TypeConstructor ctor) = do
82 env <- getEnv
83 when (ctor `M.member` typeSynonyms env) $ throwError "Type synonym instances are disallowed"
84 return ()
85checkTypeClassInstance m (TypeApp ty (TypeVar _)) = checkTypeClassInstance m ty
86checkTypeClassInstance _ _ = throwError "Type class instance must be of the form T a1 ... an"
88-- |
89-- Type check all declarations in a module
90--
91-- At this point, many declarations will have been desugared, but it is still necessary to
92--
93-- * Kind-check all types and add them to the @Environment@
94--
95-- * Type-check all values and add them to the @Environment@
96--
97-- * Bring type class instances into scope
98--
99-- * Process module imports
100--
101typeCheckAll :: Maybe ModuleName -> ModuleName -> [Declaration] -> Check [Declaration]
102typeCheckAll _ _ [] = return []
103typeCheckAll mainModuleName moduleName (d@(DataDeclaration name args dctors) : rest) = do
104 rethrow (("Error in type constructor " ++ show name ++ ":\n") ++) $ do
105 ctorKind <- kindsOf moduleName name args (concatMap snd dctors)
106 addDataType moduleName name args dctors ctorKind
107 ds <- typeCheckAll mainModuleName moduleName rest
108 return $ d : ds
109typeCheckAll mainModuleName moduleName (d@(DataBindingGroupDeclaration tys) : rest) = do
110 rethrow ("Error in data binding group:\n" ++) $ do
111 let syns = mapMaybe toTypeSynonym tys
112 let dataDecls = mapMaybe toDataDecl tys
113 (syn_ks, data_ks) <- kindsOfAll moduleName syns (map (\(name, args, dctors) -> (name, args, concatMap snd dctors)) dataDecls)
114 forM_ (zip dataDecls data_ks) $ \((name, args, dctors), ctorKind) ->
115 addDataType moduleName name args dctors ctorKind
116 forM_ (zip syns syn_ks) $ \((name, args, ty), kind) ->
117 addTypeSynonym moduleName name args ty kind
118 ds <- typeCheckAll mainModuleName moduleName rest
119 return $ d : ds
120 where
121 toTypeSynonym (TypeSynonymDeclaration nm args ty) = Just (nm, args, ty)
122 toTypeSynonym _ = Nothing
123 toDataDecl (DataDeclaration nm args dctors) = Just (nm, args, dctors)
124 toDataDecl _ = Nothing
125typeCheckAll mainModuleName moduleName (d@(TypeSynonymDeclaration name args ty) : rest) = do
126 rethrow (("Error in type synonym " ++ show name ++ ":\n") ++) $ do
127 kind <- kindsOf moduleName name args [ty]
128 addTypeSynonym moduleName name args ty kind
129 ds <- typeCheckAll mainModuleName moduleName rest
130 return $ d : ds
131typeCheckAll _ _ (TypeDeclaration _ _ : _) = error "Type declarations should have been removed"
132typeCheckAll mainModuleName moduleName (ValueDeclaration name [] Nothing val : rest) = do
133 d <- rethrow (("Error in declaration " ++ show name ++ ":\n") ++) $ do
134 valueIsNotDefined moduleName name
135 [(_, (val', ty))] <- typesOf mainModuleName moduleName [(name, val)]
136 addValue moduleName name ty
137 return $ ValueDeclaration name [] Nothing val'
138 ds <- typeCheckAll mainModuleName moduleName rest
139 return $ d : ds
140typeCheckAll _ _ (ValueDeclaration{} : _) = error "Binders were not desugared"
141typeCheckAll mainModuleName moduleName (BindingGroupDeclaration vals : rest) = do
142 d <- rethrow (("Error in binding group " ++ show (map fst vals) ++ ":\n") ++) $ do
143 forM_ (map fst vals) $ \name ->
144 valueIsNotDefined moduleName name
145 tys <- typesOf mainModuleName moduleName vals
146 vals' <- forM (zip (map fst vals) (map snd tys)) $ \(name, (val, ty)) -> do
147 addValue moduleName name ty
148 return (name, val)
149 return $ BindingGroupDeclaration vals'
150 ds <- typeCheckAll mainModuleName moduleName rest
151 return $ d : ds
152typeCheckAll mainModuleName moduleName (d@(ExternDataDeclaration name kind) : rest) = do
153 env <- getEnv
154 putEnv $ env { types = M.insert (Qualified (Just moduleName) name) kind (types env) }
155 ds <- typeCheckAll mainModuleName moduleName rest
156 return $ d : ds
157typeCheckAll mainModuleName moduleName (d@(ExternDeclaration importTy name _ ty) : rest) = do
158 rethrow (("Error in foreign import declaration " ++ show name ++ ":\n") ++) $ do
159 env <- getEnv
160 kind <- kindOf moduleName ty
161 guardWith "Expected kind *" $ kind == Star
162 case M.lookup (moduleName, name) (names env) of
163 Just _ -> throwError $ show name ++ " is already defined"
164 Nothing -> putEnv (env { names = M.insert (moduleName, name) (ty, Extern importTy) (names env) })
165 ds <- typeCheckAll mainModuleName moduleName rest
166 return $ d : ds
167typeCheckAll mainModuleName moduleName (d@(FixityDeclaration _ name) : rest) = do
168 ds <- typeCheckAll mainModuleName moduleName rest
169 env <- getEnv
170 guardWith ("Fixity declaration with no binding: " ++ name) $ M.member (moduleName, Op name) $ names env
171 return $ d : ds
172typeCheckAll mainModuleName currentModule (d@(ImportDeclaration moduleName idents) : rest) = do
173 env <- getEnv
174 rethrow errorMessage $ do
175 guardWith ("Module " ++ show moduleName ++ " does not exist") $ moduleExists env
176 case idents of
177 Nothing -> do
178 shadowIdents (map snd $ filterModule (names env)) env
179 Just idents' -> do
180 shadowIdents (nameImports idents') env
181 shadowTypeClassInstances env
182 ds <- typeCheckAll mainModuleName currentModule rest
183 return $ d : ds
184 where
185 errorMessage = (("Error in import declaration " ++ show moduleName ++ ":\n") ++)
186 filterModule = filter ((== moduleName) . fst) . M.keys
187 filterModuleQ = filter (\(Qualified (Just mn) _) -> mn == moduleName) . M.keys
188 moduleExists env = not (null (filterModule (names env))) || not (null (filterModuleQ (types env)))
189 shadowIdents idents' env =
190 forM_ idents' $ \ident ->
191 case (moduleName, ident) `M.lookup` names env of
192 Just (_, Alias _ _) -> return ()
193 Just (pt, _) -> do
194 guardWith (show currentModule ++ "." ++ show ident ++ " is already defined") $ (currentModule, ident) `M.notMember` names env
195 modifyEnv (\e -> e { names = M.insert (currentModule, ident) (pt, Alias moduleName ident) (names e) })
196 Nothing -> throwError (show moduleName ++ "." ++ show ident ++ " is undefined")
197 shadowTypeClassInstances env = do
198 let instances = filter (\tcd ->
199 let Qualified (Just mn) _ = tcdName tcd in
200 moduleName == mn && tcdType tcd == TCDRegular
201 ) (typeClassDictionaries env)
202 forM_ instances $ \tcd -> do
203 let (Qualified _ ident) = tcdName tcd
204 addTypeClassDictionaries [tcd { tcdName = Qualified (Just currentModule) ident, tcdType = TCDAlias (tcdName tcd) }]
205 constructs (TypeConstructor (Qualified (Just mn) pn')) pn
206 = mn == moduleName && pn' == pn
207 constructs (ForAll _ ty _) pn = ty `constructs` pn
208 constructs (TypeApp (TypeApp t _) ty) pn | t == tyFunction = ty `constructs` pn
209 constructs (TypeApp ty _) pn = ty `constructs` pn
210 constructs fn _ = error $ "Invalid arguments to constructs: " ++ show fn
211typeCheckAll mainModuleName moduleName (d@TypeClassDeclaration{} : rest) = do
212 env <- getEnv
213 ds <- typeCheckAll mainModuleName moduleName rest
214 return $ d : ds
215typeCheckAll mainModuleName moduleName (d@(TypeInstanceDeclaration deps className tys _) : rest) = do
216 env <- getEnv
217 dictName <- Check . lift $ mkDictionaryValueName moduleName className tys
218 mapM_ (checkTypeClassInstance moduleName) tys
219 forM_ deps $ mapM_ (checkTypeClassInstance moduleName) . snd
220 addTypeClassDictionaries [TypeClassDictionaryInScope (Qualified (Just moduleName) dictName) className tys (Just deps) TCDRegular]
221 ds <- typeCheckAll mainModuleName moduleName rest
222 return $ d : ds