func roman2arabic(roman) {
 
    var arabic = 0
    var last_digit = 1000
 
    static m = Hash(
        I =>    1,
        V =>    5,
        X =>   10,
        L =>   50,
        C =>  100,
        D =>  500,
        M => 1000,
    )
 
    roman.uc.chars.map{m{_} \\ 0}.each { |digit|
        if (last_digit < digit) {
            arabic -= (2 * last_digit)
        }
        arabic += (last_digit = digit)
    }
 
    return arabic
}
 
%w(MCMXC MMVIII MDCLXVI).each { |roman_digit|
    "%-10s == %d\n".printf(roman_digit, roman2arabic(roman_digit))
}