nom::is_not!

macro_rules! is_not {
    ($input:expr, $arr:expr) => { ... };
}

is_not!(&[T:AsBytes]) => &[T] -> IResult<&[T], &[T]> returns the longest list of bytes that do not appear in the provided array

 named!( not_space, is_not!( " \t\r\n" ) );

 let r = not_space(&b"abcdefgh\nijkl"[..]);
 assert_eq!(r, Done(&b"\nijkl"[..], &b"abcdefgh"[..]));