gistfile1.txt

use Test;

my %steps =
    90 => 'XC',
    50 => 'L',
    40 => 'XL',
    10 => 'X',
    9  => 'IX',
    5  => 'V',
    4  => 'IV',
    1  => 'I',
;

sub roman($n) {
    return '' if $n == 0;
    for %steps.keys.sort({ $^b <=> $^a }) -> $i {
        if $n >= $i {
            return %steps{$i} ~ roman($n - $i)
        }
    }
}

my %tests =
    1 => 'I',
    2 => 'II',
    3 => 'III',
    4 => 'IV',
    5 => 'V',
    6 => 'VI',
    7 => 'VII',
    8 => 'VIII',
    9 => 'IX',
    10 => 'X',
    11 => 'XI',
    18 => 'XVIII',
    19 => 'XIX',
    20 => 'XX',
    40 => 'XL',
    41 => 'XLI',
    42 => 'XLII',
    50 => 'L',
    51 => 'LI',
    52 => 'LII',
    89 => 'LXXXIX',
    90 => 'XC',
    91 => 'XCI',
;

for %tests.keys.sort -> $t {
    is roman($t), %tests{$t}
}

done;