state preserving uniq

[Chady]

removes duplicate lines like UNIX uniq without having to sort the lines first, and preserves the line positions keeping the first match in the list.

#!/usr/bin/perl

while (<>) {
    next if (defined $list{$_});
    $list{lc($_)} = [ $i++, $_ ];
}

print map { $_->[1] }
      sort { $a->[0] <=> $b->[0] } values %list;