>>Since I write this value to a log file, I want to be sure that it is always a string, not a numeric value. Can you think of a case where program(program(-1)-1) will give a numeric value?
Whenever potentially different vartypes are involved you might consider a Transform() wrapper. Transform() has been included for years in West Wind script compilation where it avoids vartype errors at very low cost.
"... They ne'er cared for us
yet: suffer us to famish, and their store-houses
crammed with grain; make edicts for usury, to
support usurers; repeal daily any wholesome act
established against the rich, and provide more
piercing statutes daily, to chain up and restrain
the poor. If the wars eat us not up, they will; and
there's all the love they bear us."
-- Shakespeare: Coriolanus, Act 1, scene 1
