[shiro]

A kind of nitpick, but the use of dynamic-wind with custodian in the slides bothers me. Dynamic-wind shouldn't directly be used to ensure cleanup, since a continuation captured in the body may be invoked outside from dynamic-wind and the body restarts, even if resources are gone.

In the R5RS age, light users looked for try-catch construct in Scheme and could only find dynamic-wind and used it; but they're not the same. Dynamic-wind is a low-level construct that can be used to implement try-catch idiom and other stuff.

Now Scheme has guard, so it's better to use them to write cleanup stuff. It's a bit verbose, though (you have to write cleanup both in the handler and the end of body), so I personally wrote unwind-protect macro on top of it and am using it.