$cat = 'ata';
SWITCH: for ($cat) # make $_ = $cat, you could do it by hand
{
    # syntaxt
    # whatever test on $_ && do { $this = 'if test passed'; last;};
    (length $_ > 1) && do { die "\$cat must be one letter not: `$cat'"; last;};
    /t/ && do { $catfile = "notitec.html"; last; };
    /a/ && do { $catfile = "notiagro.html"; last; };
    /d/ && do { $catfile = "notideportes.html"; last; };
    /h/ && do { $catfile = "notihogar.html"; last; };
    /r/ && do { $catfile = "notirecrea.html"; last; };
    /s/ && do { $catfile = "notisociales.html"; last; };
    die "unknown value for \$cat: `$cat'";
    # could just as easily be the default value
}