General pattern for interactive text-mode script?

[Anonymous Monk]

What's a good way to structure an interactive text-mode script? That is, one that presents to the user multiple questions, with subsequent questions depending upon answers already given.

Here's the kind of pseudo-code that immediately comes to mind, but which gets unmanageable very quickly:

my $main_choice;
while ($main_choice = prompt(...)) {
    if ($main_choice eq 'task_1') {
        my $next_choice = prompt(...);
        if ($next_choice eq 'task_1_a') {
            #...
        }
        elsif ($next_choice eq 'task_1_b') {
            my $deeper_choice = prompt();
            if ($deeper_choice eq 'task_1_b_1') {
                #...
            }
            elsif ($next_choice eq 'task_1_b_2') {
                #...
            }
            else {
                #...
            }
        }
        elsif ($next_choice eq 'task_1_c') {
            #...
        }
        else {
            #...
        }
    }
    elsif ($main_choice eq 'task_2') {
        #...
    }
    else {
        #...
    }
}