can't overstate how nice raku is, bit sharper learning curve but still

    raku:       ^ ( \d+ <?{ $/ <= 255 }> ) ** 4 % '.'  $
    slow raku:  ^ ( @(0..255) ) ** 4 % '.' $ 
    rulex:      <% ( :( range '0'-'255' ) '.' ){3} :( range '0'-'255' ) %>
    regex:      ^(?:(0|1[0-9]{0,2}|2(?:[0-4][0-9]?|5[0-5]?|[6-9])?|[3-9][0-9]?)\.)((0|1[0-9]{0,2}|2(?:[0-4][0-9]?|5[0-5]?|[6-9])?|[3-9][0-9]?))$

first one running code in the middle of the regex, to see if it matches a mathematical property, the second, running code to generate a [0|1|2|3|...|254|255] equivalent, which also matches as tightly as the rulex/regex code (e.g. no 00 allowed)