Macro nom::into

macro_rules! into {
    ($i:expr, $submac:ident!( $($args:tt)* )) => { ... };
    ($i:expr, $f:expr) => { ... };
}

into!(I -> IResult<I, O1, E1>) => I -> IResult<I, O2, E2> automatically converts the child parser's result to another type

it will be able to convert the output value and the error value as long as the Into implementations are available

 named!(parse_to_str<&str, &str>, take!(4));
 named!(parse_to_vec<&str, Vec<u8>>, into!(parse_to_str));