join ':', $x - 1, $y - 1
join ':', @_

##</code><code>##

pack 'ii', $x - 1, $y - 1
pack 'ii', @_

##</code><code>##

> perl -MO=Terse -e "split /:/, $z"
LISTOP (0x2bf88f8) leave [1]
    OP (0x25b59a0) enter
    COP (0x2bf8940) nextstate
    LISTOP (0x25b59d8) split [2]
        PMOP (0x25b5a60) pushre
        UNOP (0x25b5a20) null [15]
            PADOP (0x25b5ad0) gvsv  GV (0x25b0660) *z
        SVOP (0x25b5938) const [3] IV (0x25b0d80) 0
> perl -MO=Terse -e "unpack 'ii', $z"
LISTOP (0x2c387f8) leave [1]
    OP (0x645908) enter
    COP (0x645940) nextstate
    LISTOP (0x6459d8) unpack
        OP (0x6459a0) null [3]
        SVOP (0x645aa0) const [2] PV (0x63fd40) "ii"
        UNOP (0x645a20) null [15]
            PADOP (0x645a60) gvsv  GV (0x63fe00) *z
> perl -MO=Terse -e "join ':', @_"
LISTOP (0x2a9d798) leave [1]
    OP (0x24f5938) enter
    COP (0x24f5970) nextstate
    LISTOP (0x24f5a08) join [3]
        OP (0x24f59d0) pushmark
        SVOP (0x24f5ad0) const [4] PV (0x24f0960) ":"
        UNOP (0x24f5a50) rv2av [2]
            PADOP (0x24f5a90) gv  GV (0xe9b2c8) *_
> perl -MO=Terse -e "pack 'ii', @_"
LISTOP (0x2c4e318) leave [1]
    OP (0x645938) enter
    COP (0x645970) nextstate
    LISTOP (0x645a08) pack [3]
        OP (0x6459d0) pushmark
        SVOP (0x645ad0) const [4] PV (0x640a80) "ii"
        UNOP (0x645a50) rv2av [2]
            PADOP (0x645a90) gv  GV (0xffb2c8) *_

##</code><code>##

for my $r ( [-123456789, 987654321], [1,2] ) {
   my $pp = pack 'ii', @{$r};
   my $jj = join ':', @{$r};
   my $pplen = length $pp;
   my $jjlen = length $jj;
   print "$r->[0]:$r->[1] packlen=$pplen joinlen=$jjlen\n";
   my ($xpp, $ypp) = unpack 'ii', $pp;
   my ($xjj, $yjj) = split /:/, $jj;
   $xpp == $r->[0] or die;
   $ypp == $r->[1] or die;
   $xjj == $r->[0] or die;
   $yjj == $r->[1] or die;
}

##</code><code>##

-123456789:987654321 packlen=8 joinlen=20
1:2 packlen=8 joinlen=3