{-# LANGUAGE FlexibleContexts #-}

module Postdelay.Utils
  ( hoistParsecT
  ) where

import Control.Monad.Error.Class

import Data.Functor
import Data.Either

import Data.Functor.Identity
import Text.Parsec.Prim
import Text.Parsec.Error

hoistParsecT :: (Monad m, Stream s Identity t, Stream s m t) => ParsecT s u Identity a -> ParsecT s u m a
hoistParsecT p = do
  st <- getParserState
  let res = runParser p' undefined "" undefined
      p' = setParserState st >> ((,) <$> getState <*> p)
  either (fail . show) (\(st', res) -> putState st' $> res) $ res