git.iko.soy/rowtype-yoga/purescript-native
on 5d428e9 help sign in
rowtype-yoga/purescript-native/src/PureScript/TypeChecker/Monad.hs
66 lines 1.9 kB history raw
1-----------------------------------------------------------------------------
2--
3-- Module : PureScript.TypeChecker.Monad
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-----------------------------------------------------------------------------
15{-# LANGUAGE GeneralizedNewtypeDeriving, FlexibleInstances #-}
17module PureScript.TypeChecker.Monad where
19import PureScript.Types
20import PureScript.Kinds
22import Control.Applicative
23import Control.Monad.State
24import Control.Monad.Error
26import Control.Arrow ((***))
28import qualified Data.Map as M
30data NameKind = Value | Extern deriving Show
32data TypeDeclarationKind = Data | TypeSynonym deriving Show
34data Environment = Environment
35 { names :: M.Map String (PolyType, NameKind)
36 , types :: M.Map String (Kind, TypeDeclarationKind)
37 , dataConstructors :: M.Map String PolyType
38 , typeSynonyms :: M.Map String ([String], Type)
39 }
41emptyEnvironment :: Environment
42emptyEnvironment = Environment M.empty M.empty M.empty M.empty
44newtype Check a = Check { unCheck :: StateT (Environment, Int) (Either String) a } deriving (Functor, Monad, Applicative, MonadPlus, MonadState (Environment, Int), MonadError String)
46getEnv :: Check Environment
47getEnv = fmap fst get
49putEnv :: Environment -> Check ()
50putEnv env = fmap (const env *** id) get >>= put
52fresh :: Check Int
53fresh = do
54 (env, n) <- get
55 put (env, n + 1)
56 return n
58check :: Check a -> Either String (a, Environment)
59check = fmap (id *** fst) . flip runStateT (emptyEnvironment, 0) . unCheck
61guardWith :: (MonadError e m) => e -> Bool -> m ()
62guardWith _ True = return ()
63guardWith e False = throwError e
65rethrow :: (MonadError e m) => (e -> e) -> m a -> m a
66rethrow f = flip catchError $ \e -> throwError (f e)