Defining an exception type in Rust

Exception handling

Catching all exceptions
Catching a specific exception
Throwing an exception
Rethrowing exceptions
Defining an exception type
Guaranteed execution (finally)
If no exception occurs
Method throwing an exception
Throw expressions
Calling panic()

use std::{error::Error, fmt};

#[derive(Debug)]
struct SimpleError;

impl Error for SimpleError {}

impl fmt::Display for SimpleError {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "Something happened!")
    }
}

fn show_error()-> Result<(), SimpleError> {
    Err(SimpleError)
}

if let Err(err) = show_error() {
    println!("{}", err.to_string());
}