Sam Caldwell

There is a `supervise` form and a small example of its use [here](https://github.com/tonyg/syndicate/blob/master/racket/syndicate/examples/actor/example-supervise.rkt). Supervision could be integrated more tightly with `during/spawn`; as is, you can use the optional `#:on-crash` argument...

You would have the `#:on-crash` `spawn` an actor with the same behavior. To avoid duplicating the code, you'd probably need to lift it out to a function, as in: ```racket...

Chiming in to say that I wrote a `subst-all` the other day as well. My use case was pattern matching, building up an explicit substitution while walking over a value...

> Also, is there any case where we want `let` rather than `let*`? In a working code, all `let` can be converted to `let*`, so we might as well default...