-- |

{-# LANGUAGE FlexibleInstances #-}

module Language.PureScript.TypeChecker (

module T,

typeCheckModule

) where

import Language.PureScript.TypeChecker.Monad as T

import Language.PureScript.TypeChecker.Kinds as T

import Language.PureScript.TypeChecker.Types as T

import Language.PureScript.TypeChecker.Synonyms as T

import Data.Maybe

import Data.List (nub, (\\))

import Data.Foldable (for_)

import qualified Data.Map as M

import Control.Monad.State

import Control.Monad.Error.Class (MonadError(..))

import Language.PureScript.Types

import Language.PureScript.Names

import Language.PureScript.Kinds

import Language.PureScript.AST

import Language.PureScript.TypeClassDictionaries

import Language.PureScript.Environment

import Language.PureScript.Errors

addDataType :: ModuleName -> DataDeclType -> ProperName -> [(String, Maybe Kind)] -> [(ProperName, [Type])] -> Kind -> Check ()

addDataType moduleName dtype name args dctors ctorKind = do

env <- getEnv

putEnv $ env { types = M.insert (Qualified (Just moduleName) name) (ctorKind, DataType args dctors) (types env) }

forM_ dctors $ \(dctor, tys) ->

rethrow (onErrorMessages (ErrorInDataConstructor dctor)) $

addDataConstructor moduleName dtype name (map fst args) dctor tys

addDataConstructor :: ModuleName -> DataDeclType -> ProperName -> [String] -> ProperName -> [Type] -> Check ()

addDataConstructor moduleName dtype name args dctor tys = do

env <- getEnv

mapM_ checkTypeSynonyms tys

let retTy = foldl TypeApp (TypeConstructor (Qualified (Just moduleName) name)) (map TypeVar args)

let dctorTy = foldr function retTy tys

let polyType = mkForAll args dctorTy

let fields = [Ident ("value" ++ show n) | n <- [0..(length tys - 1)]]

putEnv $ env { dataConstructors = M.insert (Qualified (Just moduleName) dctor) (dtype, name, polyType, fields) (dataConstructors env) }

addTypeSynonym :: ModuleName -> ProperName -> [(String, Maybe Kind)] -> Type -> Kind -> Check ()

addTypeSynonym moduleName name args ty kind = do

env <- getEnv

checkTypeSynonyms ty

putEnv $ env { types = M.insert (Qualified (Just moduleName) name) (kind, TypeSynonym) (types env)

, typeSynonyms = M.insert (Qualified (Just moduleName) name) (args, ty) (typeSynonyms env) }

valueIsNotDefined :: ModuleName -> Ident -> Check ()

valueIsNotDefined moduleName name = do

env <- getEnv

case M.lookup (moduleName, name) (names env) of

Just _ -> throwError . errorMessage $ RedefinedIdent name

Nothing -> return ()

addValue :: ModuleName -> Ident -> Type -> NameKind -> Check ()

addValue moduleName name ty nameKind = do

env <- getEnv

putEnv (env { names = M.insert (moduleName, name) (ty, nameKind, Defined) (names env) })

addTypeClass :: ModuleName -> ProperName -> [(String, Maybe Kind)] -> [Constraint] -> [Declaration] -> Check ()

addTypeClass moduleName pn args implies ds =

let members = map toPair ds in

modify $ \st -> st { checkEnv = (checkEnv st) { typeClasses = M.insert (Qualified (Just moduleName) pn) (args, members, implies) (typeClasses . checkEnv $ st) } }

where

toPair (TypeDeclaration ident ty) = (ident, ty)

toPair (PositionedDeclaration _ _ d) = toPair d

toPair _ = error "Invalid declaration in TypeClassDeclaration"

addTypeClassDictionaries :: [TypeClassDictionaryInScope] -> Check ()

addTypeClassDictionaries entries =

let mentries = M.fromList [ ((canonicalizeDictionary entry, mn), entry) | entry@TypeClassDictionaryInScope{ tcdName = Qualified mn _ } <- entries ]

in modify $ \st -> st { checkEnv = (checkEnv st) { typeClassDictionaries = (typeClassDictionaries . checkEnv $ st) `M.union` mentries } }

checkDuplicateTypeArguments :: [String] -> Check ()

checkDuplicateTypeArguments args = for_ firstDup $ \dup ->

throwError . errorMessage $ DuplicateTypeArgument dup

where

firstDup :: Maybe String

firstDup = listToMaybe $ args \\ nub args

checkTypeClassInstance :: ModuleName -> Type -> Check ()

checkTypeClassInstance _ (TypeVar _) = return ()

checkTypeClassInstance _ (TypeConstructor ctor) = do

env <- getEnv

when (ctor `M.member` typeSynonyms env) . throwError . errorMessage $ TypeSynonymInstance

return ()

checkTypeClassInstance m (TypeApp t1 t2) = checkTypeClassInstance m t1 >> checkTypeClassInstance m t2

checkTypeClassInstance _ ty = throwError . errorMessage $ InvalidInstanceHead ty

-- |

checkTypeSynonyms :: Type -> Check ()

checkTypeSynonyms = void . replaceAllTypeSynonyms

-- |

typeCheckAll :: Maybe ModuleName -> ModuleName -> [DeclarationRef] -> [Declaration] -> Check [Declaration]

typeCheckAll mainModuleName moduleName exps = go

where

go :: [Declaration] -> Check [Declaration]

go [] = return []

go (DataDeclaration dtype name args dctors : rest) = do

rethrow (onErrorMessages (ErrorInTypeConstructor name)) $ do

when (dtype == Newtype) $ checkNewtype dctors

checkDuplicateTypeArguments $ map fst args

ctorKind <- kindsOf True moduleName name args (concatMap snd dctors)

let args' = args `withKinds` ctorKind

addDataType moduleName dtype name args' dctors ctorKind

ds <- go rest

return $ DataDeclaration dtype name args dctors : ds

where

checkNewtype :: [(ProperName, [Type])] -> Check ()

checkNewtype [(_, [_])] = return ()

checkNewtype [(_, _)] = throwError . errorMessage $ InvalidNewtype

checkNewtype _ = throwError . errorMessage $ InvalidNewtype

go (d@(DataBindingGroupDeclaration tys) : rest) = do

rethrow (onErrorMessages ErrorInDataBindingGroup) $ do

let syns = mapMaybe toTypeSynonym tys

let dataDecls = mapMaybe toDataDecl tys

(syn_ks, data_ks) <- kindsOfAll moduleName syns (map (\(_, name, args, dctors) -> (name, args, concatMap snd dctors)) dataDecls)

forM_ (zip dataDecls data_ks) $ \((dtype, name, args, dctors), ctorKind) -> do

checkDuplicateTypeArguments $ map fst args

let args' = args `withKinds` ctorKind

addDataType moduleName dtype name args' dctors ctorKind

forM_ (zip syns syn_ks) $ \((name, args, ty), kind) -> do

checkDuplicateTypeArguments $ map fst args

let args' = args `withKinds` kind

addTypeSynonym moduleName name args' ty kind

ds <- go rest

return $ d : ds

where

toTypeSynonym (TypeSynonymDeclaration nm args ty) = Just (nm, args, ty)

toTypeSynonym (PositionedDeclaration _ _ d') = toTypeSynonym d'

toTypeSynonym _ = Nothing

toDataDecl (DataDeclaration dtype nm args dctors) = Just (dtype, nm, args, dctors)

toDataDecl (PositionedDeclaration _ _ d') = toDataDecl d'

toDataDecl _ = Nothing

go (TypeSynonymDeclaration name args ty : rest) = do

rethrow (onErrorMessages (ErrorInTypeSynonym name)) $ do

checkDuplicateTypeArguments $ map fst args

kind <- kindsOf False moduleName name args [ty]

let args' = args `withKinds` kind

addTypeSynonym moduleName name args' ty kind

ds <- go rest

return $ TypeSynonymDeclaration name args ty : ds

go (TypeDeclaration _ _ : _) = error "Type declarations should have been removed"

go (ValueDeclaration name nameKind [] (Right val) : rest) = do

d <- rethrow (onErrorMessages (ErrorInValueDeclaration name)) $ do

valueIsNotDefined moduleName name

[(_, (val', ty))] <- typesOf mainModuleName moduleName [(name, val)]

addValue moduleName name ty nameKind

return $ ValueDeclaration name nameKind [] $ Right val'

ds <- go rest

return $ d : ds

go (ValueDeclaration{} : _) = error "Binders were not desugared"

go (BindingGroupDeclaration vals : rest) = do

d <- rethrow (onErrorMessages (ErrorInBindingGroup (map (\(ident, _, _) -> ident) vals))) $ do

forM_ (map (\(ident, _, _) -> ident) vals) $ \name ->

valueIsNotDefined moduleName name

tys <- typesOf mainModuleName moduleName $ map (\(ident, _, ty) -> (ident, ty)) vals

vals' <- forM [ (name, val, nameKind, ty)

| (name, nameKind, _) <- vals

, (name', (val, ty)) <- tys

, name == name'

] $ \(name, val, nameKind, ty) -> do

addValue moduleName name ty nameKind

return (name, nameKind, val)

return $ BindingGroupDeclaration vals'

ds <- go rest

return $ d : ds

go (d@(ExternDataDeclaration name kind) : rest) = do

env <- getEnv

putEnv $ env { types = M.insert (Qualified (Just moduleName) name) (kind, ExternData) (types env) }

ds <- go rest

return $ d : ds

go (d@(ExternDeclaration name ty) : rest) = do

rethrow (onErrorMessages (ErrorInForeignImport name)) $ do

env <- getEnv

kind <- kindOf moduleName ty

guardWith (errorMessage (ExpectedType kind)) $ kind == Star

case M.lookup (moduleName, name) (names env) of

Just _ -> throwError . errorMessage $ RedefinedIdent name

Nothing -> putEnv (env { names = M.insert (moduleName, name) (ty, External, Defined) (names env) })

ds <- go rest

return $ d : ds

go (d@(FixityDeclaration _ name) : rest) = do

ds <- go rest

env <- getEnv

guardWith (errorMessage (OrphanFixityDeclaration name)) $ M.member (moduleName, Op name) $ names env

return $ d : ds

go (d@(ImportDeclaration importedModule _ _) : rest) = do

tcds <- getTypeClassDictionaries

let instances = filter (\tcd -> let Qualified (Just mn) _ = tcdName tcd in importedModule == mn) tcds

addTypeClassDictionaries [ tcd { tcdName = Qualified (Just moduleName) ident, tcdType = TCDAlias (canonicalizeDictionary tcd) }

| tcd <- instances

, tcdExported tcd

, let (Qualified _ ident) = tcdName tcd

]

ds <- go rest

return $ d : ds

go (d@(TypeClassDeclaration pn args implies tys) : rest) = do

addTypeClass moduleName pn args implies tys

ds <- go rest

return $ d : ds

go (d@(TypeInstanceDeclaration dictName deps className tys _) : rest) = do

goInstance d dictName deps className tys rest

go (d@(ExternInstanceDeclaration dictName deps className tys) : rest) = do

goInstance d dictName deps className tys rest

go (PositionedDeclaration pos com d : rest) =

rethrowWithPosition pos $ do

(d' : rest') <- go (d : rest)

return (PositionedDeclaration pos com d' : rest')

goInstance :: Declaration -> Ident -> [Constraint] -> Qualified ProperName -> [Type] -> [Declaration] -> Check [Declaration]

goInstance d dictName deps className tys rest = do

mapM_ (checkTypeClassInstance moduleName) tys

forM_ deps $ mapM_ (checkTypeClassInstance moduleName) . snd

addTypeClassDictionaries [TypeClassDictionaryInScope (Qualified (Just moduleName) dictName) className tys (Just deps) TCDRegular isInstanceExported]

ds <- go rest

return $ d : ds

where

isInstanceExported :: Bool

isInstanceExported = any exportsInstance exps

exportsInstance :: DeclarationRef -> Bool

exportsInstance (TypeInstanceRef name) | name == dictName = True

exportsInstance (PositionedDeclarationRef _ _ r) = exportsInstance r

exportsInstance _ = False

-- |

-- This function adds the argument kinds for a type constructor so that they may appear in the externs file,

-- extracted from the kind of the type constructor itself.

--

withKinds :: [(String, Maybe Kind)] -> Kind -> [(String, Maybe Kind)]

withKinds [] _ = []

withKinds (s@(_, Just _ ):ss) (FunKind _ k) = s : withKinds ss k

withKinds ( (s, Nothing):ss) (FunKind k1 k2) = (s, Just k1) : withKinds ss k2

withKinds _ _ = error "Invalid arguments to peelKinds"

-- |

typeCheckModule :: Maybe ModuleName -> Module -> Check Module

typeCheckModule _ (Module _ _ _ Nothing) = error "exports should have been elaborated"

typeCheckModule mainModuleName (Module coms mn decls (Just exps)) = rethrow (onErrorMessages (ErrorInModule mn)) $ do

modify (\s -> s { checkCurrentModule = Just mn })

decls' <- typeCheckAll mainModuleName mn exps decls

forM_ exps $ \e -> do

checkTypesAreExported e

checkClassMembersAreExported e

checkClassesAreExported e

return $ Module coms mn decls' (Just exps)

where

checkMemberExport :: (Type -> [DeclarationRef]) -> DeclarationRef -> Check ()

checkMemberExport extract dr@(ValueRef name) = do

ty <- lookupVariable mn (Qualified (Just mn) name)

case filter (not . exported) (extract ty) of

[] -> return ()

hidden -> throwError . errorMessage $ TransitiveExportError dr hidden

where

exported e = any (exports e) exps

exports (TypeRef pn1 _) (TypeRef pn2 _) = pn1 == pn2

exports (ValueRef id1) (ValueRef id2) = id1 == id2

exports (TypeClassRef pn1) (TypeClassRef pn2) = pn1 == pn2

exports (TypeInstanceRef id1) (TypeInstanceRef id2) = id1 == id2

exports (PositionedDeclarationRef _ _ r1) r2 = exports r1 r2

exports r1 (PositionedDeclarationRef _ _ r2) = exports r1 r2

exports _ _ = False

checkMemberExport _ _ = return ()

-- Check that all the type constructors defined in the current module that appear in member types

-- have also been exported from the module

checkTypesAreExported :: DeclarationRef -> Check ()

checkTypesAreExported = checkMemberExport findTcons

where

findTcons :: Type -> [DeclarationRef]

findTcons = everythingOnTypes (++) go

where

go (TypeConstructor (Qualified (Just mn') name)) | mn' == mn = [TypeRef name (error "Data constructors unused in checkTypesAreExported")]

go _ = []

-- Check that all the classes defined in the current module that appear in member types have also

-- been exported from the module

checkClassesAreExported :: DeclarationRef -> Check ()

checkClassesAreExported = checkMemberExport findClasses

where

findClasses :: Type -> [DeclarationRef]

findClasses = everythingOnTypes (++) go

where

go (ConstrainedType cs _) = mapMaybe (fmap TypeClassRef . extractCurrentModuleClass . fst) cs

go _ = []

extractCurrentModuleClass :: Qualified ProperName -> Maybe ProperName

extractCurrentModuleClass (Qualified (Just mn') name) | mn == mn' = Just name

extractCurrentModuleClass _ = Nothing

checkClassMembersAreExported :: DeclarationRef -> Check ()

checkClassMembersAreExported dr@(TypeClassRef name) = do

let members = ValueRef `map` head (mapMaybe findClassMembers decls)

let missingMembers = members \\ exps

unless (null missingMembers) $ throwError . errorMessage $ TransitiveExportError dr members

where

findClassMembers :: Declaration -> Maybe [Ident]

findClassMembers (TypeClassDeclaration name' _ _ ds) | name == name' = Just $ map extractMemberName ds

findClassMembers (PositionedDeclaration _ _ d) = findClassMembers d

findClassMembers _ = Nothing

extractMemberName :: Declaration -> Ident

extractMemberName (PositionedDeclaration _ _ d) = extractMemberName d

extractMemberName (TypeDeclaration memberName _) = memberName

extractMemberName _ = error "Unexpected declaration in typeclass member list"

checkClassMembersAreExported _ = return ()