Read y Write en Rust

Usando Read y BufRead, nos podemos abstraer a un vector de u8

use std::io::{BufRead, BufReader, Read, Result};

fn count_lines<R: Read>(reader: R) -> usize {

    let buf_reader = BufReader::new(reader);

    buf_reader.lines().count()

}

fn main() -> Result<()> {

    let slice: &[u8] = b"foo\nbar\nbaz\n";

    println!("lines in slice: {}", count_lines(slice));

    let file = std::fs::File::open(std::env::current_exe()?)?;

    println!("lines in file: {}", count_lines(file));

    Ok(())

}

De manera similar, Write nos permite abstraernos de igual forma:

use std::io::{Result, Write};

fn log<W: Write>(writer: &mut W, msg: &str) -> Result<()> {

    writer.write_all(msg.as_bytes())?;

    writer.write_all("\n".as_bytes())

}

fn main() -> Result<()> {

    let mut buffer = Vec::new();

    log(&mut buffer, "Hello")?;

    log(&mut buffer, "World")?;

    println!("Logged: {:?}", buffer);

    Ok(())

}