Dear Shiro,

thanks for chiming in!

Am Fr., 7. Jan. 2022 um 20:48 Uhr schrieb Shiro Kawai <xxxxxx@gmail.com>:
>
> Regarding phase separation:
> With low-level macros, it is possible for the users to write code to capture continuation within the expander and save it somewhere, and invoke it at runtime.  To some extent, we need to rely on users not to carry things across phase boundaries except the syntactic forms defined by the protocol.  We can only warn users about common pitfalls.  Can this sc case be also one of such "things you should avoid"?

A Scheme system should catch such a continuation capture. That's one
reason why SRFI 226 defines continuation barriers. With them, one can
prohibit downward jumps across well-defined boundaries.

[...]

Marc