Philip McGrath

I think what I'm trying to pick at is where to draw the line for "reasonable" interposition on treelists. Or, from a slightly different point of view, what kinds of...

I haven't had time to experiment with the changes yet, hence my not commenting earlier, but I agree they seem like a good direction!

> That is, when we access an index value that's crossed the boundary already is there a way to keep track of that and not use the chaperone for that...

If you add: ```racket #:guard (λ (range name) (coerce-chaperone-contract 'range-arrow range)) ``` to the definition of `range-arrow`, you will get this more useful error: ``` range-arrow: contract violation expected: chaperone-contract?...

> my bug is more that following the steps in the Racket Guide … combined with another chaperone contract lead to a seemingly nonsensical error message The problem was that...

How did you install Racket? Did you use an RPM package, or the installer from https://download.racket-lang.org, or something else?

@bremner For Guix I fixed this by just deleting the offending file in a patch. IIRC from the linked issue, Nix did the same. (I am planning to work on...

What is the use-case for this? I am skeptical that the additional complexity would be worth it. For compatibility, the value of `(current-command-line-arguments)` would have to remain a vector of...

Re: your comment on #4810, https://github.com/racket/racket/issues/3354 has also been on my wish list. A place under `racket/private` that works well for adding one of these features would probably work well...

> the version in this PR also includes an explicit arity check I have also written this function multiple times, but I think I have rarely if ever implemented an...