#!/usr/bin/perl
use strict;
use warnings;

my @chars   =   ( "a" .. "k", "m","n", "p" .. "z");
my @upchars =   ("A".."N","P".."Z");   # <-- NOTE: "P..Z" -> "P".."Z"
my @nona    = qw(! @ $ % & ( ) + = { } [ ] < > ~);
my @nums    =   (0 .. 9);

my $lc = \@chars;
my $uc = \@upchars;
my $na = \@nona;
my $nu = \@nums;

my @types = ($lc, $uc, $na, $nu);      # compact: my @types = (\@chars, \@upchars, ...

my $a  = join("", @{$types[3]}[ map { rand @{$types[3]} } ( 1 .. 4 ) ]);
   $a .= join("", @{$types[2]}[ map { rand @{$types[2]} } ( 1 .. 4 ) ]);
   $a .= join("", @{$types[1]}[ map { rand @{$types[1]} } ( 1 .. 4 ) ]);
   $a .= join("", @{$types[0]}[ map { rand @{$types[0]} } ( 1 .. 4 ) ]);
#                  ^--deref/arrayslice      ^-- deref for number of elements

# nobody complained about using '$a' yet, so I don't do either ;-)

print "My selection is $a \n";
# you should shuffle and shorten the result

exit;

__DATA__
My selection is 0548)~}+QRVKzkkt
My selection is 7922&)(&AAZZwiaw
My selection is 5263+!@>VXXBaezt