+use feature 'signatures';
+sub vname ($v) {
+ return sprintf 'v%d%03d', unpack 'C*', $v;
+}
+sub linkversion ($v) {
+ return showlink(sprintf('%vd', $v), '#'.vname($v));
+}
+
+eval {
+ use List::Util 'first';
+ use Time::Piece;
+ use Time::Seconds;
+
+ my $now = Time::Piece->new;
+ if (my $ts = $get{at}) {
+ $now = $now->strptime($ts, '%Y-%m-%d');
+ say "Compatibility details emulated for <em>$ts</em>.";
+ }
+ my $ts = $now->strftime('%F');
+ my @versions = sort grep { $info->{$_}{release} le $ts } keys %{$info};
+
+ # perlpolicy: «We "officially" support the two most recent stable release
+ # series. [...] we will attempt to fix critical issues»
+ $info->{ $versions[-2] }{versum} //= "active core support";
+ $info->{ $versions[-1] }{versum} //= "latest stable release";
+
+ # perlpolicy: «we will attempt to fix critical issues in the two most
+ # recent stable 5.x release series»
+ my $coreeol = ($now - ONE_YEAR * 3)->strftime('%F');
+ my $vcore = first { $info->{$_}{release} ge $coreeol } @versions;
+ print "<p>Core security support is provided for 3 years";
+ print ", so typical users should run at least ", linkversion($_)
+ for $vcore // ();
+ say '.';
+ $info->{$vcore}{versum} //= "official security patches";
+
+ # «We encourage vendors to ship the most recent supported release of Perl
+ # at the time of their code freeze»
+ # assume debian ships after 1 year, and expires after 5 years LTS
+ my $vendoreol = ($now - ONE_YEAR * 6)->strftime('%F');
+ my $vdebian = first {
+ $info->{$_}{release} ge $vendoreol && $info->{$_}{distro}{debian}
+ } @versions;
+ say sprintf "Stable distributions such as Debian %s maintain %s+.",
+ $info->{$_}{distro}{debian}, linkversion($_) for $vdebian // ();
+ $info->{$vdebian}{versum} //= "still maintained by common vendors";
+
+ # extended support given at random
+ my $nowcmp = $now->strftime('%F');
+ my $vdino = first { $info->{$_}{support} ge $nowcmp } @versions;
+ say "Enterprise platforms retain versions up to $_."
+ for map { linkversion($_) } $vdino // ();
+ return 1;
+} or Alert('Missing version recommendations', $@);