c:\@Work\Perl\monks>perl -wMstrict -le
"use 5.010;
 ;;
 use Test::More 'no_plan';
 use Test::NoWarnings;
 ;;
 use Data::Dump qw(dd pp);
 ;;
 use constant TEST_1 => (
   [ [], []  ],  [ [0], [0] ],  [ [1], [1] ],  [ [-1], [-1] ],
   [ [1, 2], [1, 2]  ],  [ [1, 2, 3], [1, 2, 3] ],
   [ [1, 1], [1] ],  [ [-1, -1], [-1] ],
   [ [10, 10, 20, 0x47, 1, 71, 30, 45, 45], [1..71] ],
   [ [10, 10, -1, 20, 0x47, -5, 1, 71, -1, 30, 45, 45], [-5..71] ],
   [ [1, 5, 1, 5], [1..5] ],  [ [6, 9, 1, 5], [1..9] ],
   );
 ;;
 VECTOR:
 for my $ar_vector (TEST_1) {
   my ($ar_test, $ar_expected) = @$ar_vector;
   ;;
   my $ar_got = [ range(@$ar_test) ];
   is_deeply $ar_got, $ar_expected,
      pp($ar_test) . ' -> ' . pp($ar_expected);
   }
 ;;
 ;;
 sub range {
   my $joiner = q{,};
   my $s = join $joiner, sort { 0+$a <=> 0+$b } @_;
   ;;
   my $n = qr{ (?: \b | -) \d+ \b }xms;
   $s =~ s{ ($n) \K (?: , \1 \b)+  }''xmsg;
   ;;
   use re 'eval';
   $s =~ s{ ($n) (?{ $^N }) , \K (?= ($n) (?(?{ $^R == $^N-1 }) (*F))) }
          { join $joiner, $^R+1 .. $^N-1, '' }xmsge;
   ;;
   return split $joiner, $s;
   }
"
ok 1 - [] -> []
ok 2 - [0] -> [0]
ok 3 - [1] -> [1]
ok 4 - [-1] -> [-1]
ok 5 - [1, 2] -> [1, 2]
ok 6 - [1, 2, 3] -> [1, 2, 3]
ok 7 - [1, 1] -> [1]
ok 8 - [-1, -1] -> [-1]
ok 9 - [10, 10, 20, 71, 1, 71, 30, 45, 45] -> [1 .. 71]
ok 10 - [10, 10, -1, 20, 71, -5, 1, 71, -1, 30, 45, 45] -> [-5 .. 71]
ok 11 - [1, 5, 1, 5] -> [1 .. 5]
ok 12 - [6, 9, 1, 5] -> [1 .. 9]
ok 13 - no warnings
1..13

##</code><code>##

sub range {
  return @_ unless @_ > 1;
  my ($min, $max) = (sort { 0+$a <=> 0+$b } @_)[0, -1];
  return $min .. $max;
  }