factor out common prefixes and suffixes if possible.

prefix_suffix.pm6

my $in = "rakudo-parrot c8ec1d, rakudo-jvm c8ec1d, rakudo-moar c8ec1d, niecza v24-109-g48a8de3";
my @pieces = $in.split(", ");

class Score is rw {
    has $.prefix = 0 but "";
    has $.postfix = 0 but "";
    has @.subpieces;
    has @.rest;
    has $.output;
}

my %scoring{Any};

for @pieces.keys.combinations(1..*) {
    my @subpieces = @pieces[@$_];
    my Score $score .= new(:@subpieces);
    for 1..([max] @subpieces>>.chars) {
        last unless [eq] @subpieces>>.substr(0, $_);
        $score.prefix = $_ but @subpieces[0].substr(0, $_);
    }
    for 1..(([max] @subpieces>>.chars) - $score.prefix) {
        last unless [eq] @subpieces>>.substr(* - $_);
        $score.postfix = $_ but @subpieces[0].substr(* - $_);
    }
    $score.rest = @subpieces>>.substr($score.prefix, * - $score.postfix);
    $score.output = ~$score.prefix ~ '{' ~ $score.rest.join(", ") ~ '}' ~ ~$score.postfix;
    %scoring{@subpieces.item} = $score;
}

.value.output.say for %scoring;

# now that we have simple bits, we can construct bigger pieces out of them
# and just use the shortest for each combination

for %scoring.kv -> $pieces, $score {
    # @pieces is our target combination of bits.
    # we'll look for ways to shorten the output we've got by replacing
    # sub-sections with other smaller thingies.
    say "we're trying to improve our $pieces score";
    say %scoring.keys.perl;
    for %scoring.keys.combinations(1..*) {
        # first, check if we'll reach 100% coverage of our $pieces
        say "we're now trying to get to: $pieces";
        say $_;
        say;
    }
}