fn get_number_input(question string) {
    println(question)
    input = read_line()
    // try to parse to an int, then a float.
    in = match input {
        input.parse_int() input
        input.parse_float() input
    }
    // 'in' has type int/float/[] because of the match statement
    switch! in {
        int/float in
        // replace [] with an appropriate error before returning
        [] Err: "input was not a number."
    }
    // return type is int/float/Err(string)
}

answer = get_number_input("What is your favorite number?")

// switch can be used to branch based on a variables type.
// switch! indicates that every possible type must be handled.
switch! answer {
    int {
        println("Entered an integer")
        answer.debug() // int
    }
    float {
        println("Entered a decimal number")
        answer.debug() // float
    }
    Err(string) println("Input was not a number!")
}

sleep(2)


// function that returns an anonymous function (function object).
// anonymous functions can be used as iterators in for-loops.
fn count_up() {
    count = -1
    () {
        count = count.add(1)
        count
    }
}

for num count_up() {
    println(num.to_string())
    // once num is greater than 60,
    // the loop stops and returns num.
    if num.gt(60) num else []
}