Seems to be a bug in context evaluation in FATAL, this code works and throws an exception when readdir returns undef:

#!/usr/bin/perl

use strict;
use warnings;

use Fatal qw(readdir);

$| = 1;

my $start_dir = '.';
opendir(my $dir, $start_dir);
while($_= readdir($dir)) {
        print "$_ ";
}
closedir $dir;
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Update 2006/04/28: This apparently isn't a bug in Fatal, but simply the fact that readdir can't be correctly "fatalized" 'cause it doesn't clearly indicates failure (and only failure) returning a false value. The documentation of Fatal will be updated to reflect better when to use it.