else if(car == _symbol("abort"))
        _abort(_cdr(form), env, d)

function _abort(form, env, d,       s) {
    if(_ABORTING) {
        # avoid infinite abort loops
        print "[abort called while aborting]" > "/dev/stderr"
        exit 88
    }
    _ABORTING = 1
    s = _sprintf(_eval3(_car(form), env, env, d+1),
                 _cdr(form), env, d+1)
    print "GLOTAWK ABORT: " _STRING[s] > "/dev/stderr"
    exit 87
}

    _symbol("abort")