casDeclareOperators :: Session a => a -> [EXPRESSION] -> IO ()
casDeclareOperators sess varlist = do
  hPutStrLn (inp sess) $ "operator " ++ exportExps varlist ++ ";"
  hGetLine (outp sess)
  return ()

-- | declares an equation x := exp
casDeclareOperators :: Session a => a -> [EXPRESSION] -> IO ()
casDeclareOperators sess varlist = do
  hPutStrLn (inp sess) $ "operator " ++ exportExps varlist ++ ";"
  hGetLine (outp sess)
  return ()

-- | declares an equation x := exp
casDeclareOperators sess varlist = do
  hPutStrLn (inp sess) $ "operator " ++ exportExps varlist ++ ";"
  hGetLine (outp sess)
  return ()

-- | declares an equation x := exp