Marcus Chen

use std::mem;

fn main() {
    let mut x = 5;
    let mut y = 10;

use std::mem::MaybeUninit;

fn main() {
    let mut uninit: MaybeUninit<i32> = MaybeUninit::uninit();
    unsafe {
        uninit.as_mut_ptr().write(42);

# Install
cargo install cargo-expand

# Expand entire crate
cargo expand

// In a proc-macro crate:
use proc_macro::TokenStream;
use quote::quote;
use syn::{parse_macro_input, DeriveInput};

#[proc_macro_derive(MyTrait)]

// build.rs
fn main() {
    println!("cargo:rerun-if-changed=build.rs");

    let version = env!("CARGO_PKG_VERSION");
    println!("cargo:rustc-env=BUILD_VERSION={}", version);

use std::io::Write;
use tempfile::NamedTempFile;

fn main() -> std::io::Result<()> {
    let mut tmpfile = NamedTempFile::new()?;
    writeln!(tmpfile, "Hello, temp file!")?;

use std::process::Command;

fn main() -> std::io::Result<()> {
    let output = Command::new("ls")
        .arg("-la")
        .output()?;

use std::path::Path;

fn process_file(path: impl AsRef<Path>) {
    let path = path.as_ref();
    println!("Processing: {}", path.display());
}

use std::ops::Deref;

struct MyBox<T>(T);

impl<T> Deref for MyBox<T> {
    type Target = T;

trait Container {
    type Item;
    fn get(&self, index: usize) -> Option<&Self::Item>;
}

struct Warehouse {

use std::fmt::Display;

fn make_adder(x: i32) -> impl Fn(i32) -> i32 {
    move |y| x + y
}

const MAX_SIZE: usize = 1024;

const fn square(n: u32) -> u32 {
    n * n
}