sub reverse_complement {
    local $_ = shift;
    y/ACGT/TGCA/;
    reverse;
}

##</code><code>##

while (<FASTA>) {
    chomp;
    if (/^>\s*(.*)/) {
        # it's a sequence label
        $name = $1;
    } else {
        # it's sequence data
    }
}