sub sorted_insert (\@$) {
  my( $a, $item ) = @_;

  unless( @{$a} ) { push @{$a}, $item; return }

  my $i = 0;
  while( $i <= $#{$a} ) {
     last if $a->[$i] > $item;
     $i++;
  }

  splice( @{$a}, $i, 0, $item );

  return $a
}

@a = qw( 1 2 4 6 );

sorted_insert @a, 3;
sorted_insert @a, 7;

print join( ", ", @a ), "\n";