Quit while loop that asks for numbers with IO::Prompter

Question

While using IO::Prompter I'm asking only numbers as input. This works. However I can't seem to find an elegant way to move away from the subroutine if I enter something like 'quit'.

In the documents it said something like:

while (my $cmd = prompt '>', -fail=>'quit') {
    ...
}

But I haven't been able to implement that and tried the following that doesn't function properly (I can't quit).

#!/usr/bin/perl
use strict;
use warnings;
use IO::Prompter;

my $ask = prompt "Do you want to show numbers?", -yn;
print "You entered: $ask\n";
if ( $ask eq 'y' ) {
    showNumbers();
}
else {
    print "You said: no\n";
}

sub showNumbers {
    while ( prompt -num, 'Enter a number'){
        print "$_\n";
    }
}

Answer 1

-DEF can be used to provide a default that's not a valid response, allowing us to distinguish between a valid a response and just pressing Enter.

sub showNumbers {
    while (1) {
        my $num = prompt 'Enter a number', -num, -DEF => "";

        # $num is a weird value that true even for an empty string, so
        # we must separately check for false (meaning EOF) and empty string.
        last if !$num || $num eq "";

        print "$num\n";
    }
}