import io

fn main () {
    x := 0

    // since variable are immutable but updatable, x is 1 inside clojure, but
    // 0 inside main()
    fn inner() {
        x++
    }

    inner()

    // shows 0
    io.puts("x is {x}")

    // however, if you explicitly update x:
    x = inner()

    // shows 1
    io.puts("x is {x}")
}