Macro small_unsigned 

macro_rules! small_unsigned {
    ( $max:expr $(,)? ) => { ... };
}

Return smallest unsigned type capable of representing input value (positive, i.e. maximum).

Example

use smallnum::{small_unsigned, SmallUnsigned};
use core::mem::size_of_val;

let idx: usize = 5;
let small_idx: small_unsigned!(500) = 5;

assert_eq!(idx, small_idx.usize());
assert!(size_of_val(&idx) > size_of_val(&small_idx));