I'd mistakenly replied off-list, before re-posting here. Carl you'd pointed out, off-list:
> I believe that's right. I haven't ever done this or tested its accuracy, so > you might want to double check that there aren't weird corner cases of the > struct hierarchy, or at least that it works for the kinds of examples you > have in mind. Thanks for the caution. I did try some more cases and realized one flaw: If an immutable struct is derived from a mutable one, my predicate will (as written) incorrectly report it as immutable. Instead I need to walk the chain of super-types, and check that all are immutable. I'll work on this more... ____________________ Racket Users list: http://lists.racket-lang.org/users
