use Term::ReadKey;
use strict; use warnings;
my @completion_list = qw[ ro sham bo foo bar baz ];
{
    my $orig_prompt = "Hi: ";
    my $prompt = $orig_prompt;
    my $prev_prompt = $orig_prompt;
    my $tab = do {
        my $ix = -1;
        my $xx = @completion_list  - 1;
        sub {
            $ix++;
            return $completion_list[  $ix % $xx ];
        };
    };
    $|=1;
    print $prompt;
    my $key ;
    while( 1 ){
        $key = ReadKey(-1);
        next unless defined $key;
        if( $key eq "\r"){
            print "\n";
            last;
        } elsif( $key eq "\t" ){
            my $completion = $tab->();
            $prompt = $orig_prompt . $completion;

#~ FAIL             print "\b" x ( 1 + length $prev_prompt ), $prompt;
#~ FAIL             print "\b" x ( 100 ), $prompt;
#~ FAIL             print "\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b$prompt";
            print "\r" , " " x ( length $prev_prompt );
            print "\r", $prompt;
            $prev_prompt = $prompt;
        } elsif( $key eq "\e") {
            print "\r" , " " x ( length $prev_prompt );
            $prompt = $orig_prompt ;
            print "\r", $prompt;
            $prev_prompt = $prompt;
        } else {
            use DDS; warn Dump $key ;
        }
    }
    use DDS; warn Dump [ $key, $orig_prompt, $prompt, $prev_prompt ] ;
}