estrogen-0.1.1-indev doesn't have any documentation.
ESTROGEN
A library for compile time string generation.
Examples
estrogen::repeat
Repeat a string literal some number of times.
use repeat;
const SPACES: &'static str = repeat!;
assert_eq!;
assert_eq!;
estrogen::join
Join strings together with a separator.
use join;
const FOOBARBAZ: &'static str = join!;
assert_eq!;