module main

fn main() {
    try_propagation() or { println('captured: ${err}') }
}

fn try_propagation() ! {
    try_numbers()!
}

fn try_numbers() ! {
    for x in 1 .. 10 {
        y := error_if_even(x) or { x + 1 }
        println('${x} rounded to ${y}')
        error_if_prime(y)!
    }
}

fn error_if_even(num int) !int {
    if num % 2 == 0 {
        return error('number is even')
    }
    return num
}

fn error_if_prime(num int) !int {
    for i in 2 .. num {
        if num % i == 0 {
            return error('${num} is prime')
        }
    }
    return num
}