rust 12 lines · 1 tab

From and Into for type conversions

Marcus Chen Jan 2026

1 tab

struct UserId(u32);

impl From<u32> for UserId {
    fn from(id: u32) -> Self {
        UserId(id)
    }
}

fn main() {
    let id: UserId = 42.into();
    println!("User ID: {}", id.0);
}

1 file · rust Explain with highlit

The From and Into traits provide a standard way to convert between types. Implementing From<T> for your type automatically provides Into<T> via a blanket implementation. I use From for infallible conversions (like String::from("hello")) and TryFrom for fallible ones. This is more idiomatic than custom to_* methods. The ? operator works with From for error conversion: if your error type implements From<OtherError>, you can use ? on functions returning OtherError. I implement From for wrapping types (newtype pattern) and converting between representations. The trait makes APIs composable and consistent with standard library types.

Related snips

rust

struct Config<'a> {
    name: &'a str,
    value: &'a str,
}

fn parse_config(line: &str) -> Config {

Lifetime annotations for flexible borrowing in structs

rust lifetimes borrowing

by Marcus Chen 1 tab

rust

use crossbeam::channel::unbounded;
use std::thread;

fn main() {
    let (tx, rx) = unbounded();

Crossbeam for advanced concurrent data structures

rust concurrency lock-free

by Marcus Chen 1 tab

rust

use tracing::{info, instrument};

#[instrument]
fn process_request(user_id: u64) {
    info!(user_id, "Processing request");
    // Work happens here

tracing for structured logging and distributed tracing

rust observability tracing

by Marcus Chen 1 tab

rust

use std::sync::mpsc;
use std::thread;

fn main() {
    let (tx, rx) = mpsc::channel();

Channels (mpsc) for message passing between threads

rust concurrency channels

by Marcus Chen 1 tab

rust

use clap::Parser;

#[derive(Parser, Debug)]
#[command(author, version, about)]
struct Args {
    #[arg(short, long)]

clap for CLI argument parsing with derive macros

rust cli clap

by Marcus Chen 1 tab

rust

macro_rules! create_function {
    ($func_name:ident) => {
        fn $func_name() {
            println!("Called {}", stringify!($func_name));
        }
    };

Declarative macros (macro_rules!) for code generation

rust macros metaprogramming

by Marcus Chen 1 tab

Share this code

Here's the card — post it anywhere.

From and Into for type conversions — share card

Link copied