macro expansion in rust

rust macro_expand.md

In rust the in order to see the expansion of the macros like println! we can use the rust-expand crate

First install the crate

cargo install cargo-expand

then use cargo expand command

for eg: a hello world in rust will look like this

fn main() {
    println!("Hello, world!");
}

with cargo expand it will look like

#![feature(prelude_import)]
#[prelude_import]
use std::prelude::rust_2018::*;
#[macro_use]
extern crate std;
fn main() {
    {
        ::std::io::_print(::core::fmt::Arguments::new_v1(&["Hello, world!\n"], &[]));
    };
}