Function double_first

0a_error_handling/rust/using_eyre/src/main.rs:3–7

(vec: Vec<&str>)

use eyre::{eyre, Result};

fn double_first(vec: Vec<&str>) -> Result<i32> {
    let first = vec.first().ok_or_else(|| eyre!("no first item"))?;
    let parsed = first.parse::<i32>()?;
    Ok(2 * parsed)
}

fn print(result: Result<i32>) {
    match result {