gistfile1.txt

my $target = "METHINKS IT IS LIKE A WEASEL";
my @chars = 'A'..'Z',' ';
my $mutate-chance = 8; # percent
my $C = 100;
 
my $parent = @chars.pick($target.chars, :replace).join;
my $iter = 0;
say "#{ $iter++ }: $parent { fitness $parent }";

while $parent ne $target {
    $parent = ($parent, (^$C).map({ mutate $parent })).max({ fitness $_ });
    say "#{ $iter++ }: $parent { fitness $parent }";
}
 
sub mutate($str) {
    $str.comb.map({ 100.rand < $mutate-chance ?? @chars.pick !! $_ }).join;
}
 
sub fitness($str) {
    [+] $str.comb Zeq $target.comb;
}