indentMark :: Lexer (Pos Token)
indentMark = (<?> "indent") $ withPos $ do
    maybe parserZero return =<< peek
    string "\\\\"
    lookAhead $ char '\n'
    return Space
indentMark :: Lexer (Pos Token)
indentMark = (<?> "indent") $ withPos $ do
    maybe parserZero return =<< peek
    string "\\\\"
    lookAhead $ char '\n'
    return Space
indentMark = (<?> "indent") $ withPos $ do
    maybe parserZero return =<< peek
    string "\\\\"
    lookAhead $ char '\n'
    return Space