Prototyping? Am I missing something here? This seems to work:

sub mylcfirst {
    my $x;
    if (@_) { $x = join "", @_ }
    else    { $x = $_          }

    $x =~ s/(.)/\l$1/;
    return $x;
}

sub myuc {
    my $x;
    if (@_) { $x = join "", @_ }
    else    { $x = $_          }

    $x =~ s/(.*)/\U$1/;
    return $x;
}

sub myreverse {
    my $x;
    if (@_) { $x = join "", @_ }
    else    { $x = $_          }

    $x = reverse $x;
    return $x;
}

### sample1
$_      =   'lrep esu';
$str    =   myreverse mylcfirst myuc;
print $str."\n";

### sample2
$_      =   'lrep esu';
$str    =   mylcfirst myreverse myuc;
print $str."\n";
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Sure, the code is a little clunky. And it doesn't take reverse in list context into account, but the idea is there. What part of this isn't what you are expecting?