nom::tag_s

macro_rules! tag_s {
    ($i:expr, $tag: expr) => { ... };
}

tag_s!(&str) => &str -> IResult<&str, &str> declares a string as a suite to recognize

consumes the recognized characters

 fn test(input: &str) -> IResult<&str, &str> {
   tag_s!(input, "abcd")
 }
 let r = test("abcdefgh");
 assert_eq!(r, Done("efgh", "abcd"));