How do I wait, or sit-for, until a hook is run?

[Eduardo Ochs <eduardoochs@gmail.com>]

Hi list,

I am trying to write a function (my-sly-wait) that can be put here,

  (save-window-excursion (sly) (my-sly-wait))

and that only returns when the hook `sly-mrepl-hook' is run...

How do I write that? Or, if I can ask for something nicer... how do I
write a function like that that waits for at most 30 seconds
displaying all output like a `sit-for' (?), and returns without errors
if the hook `sly-mrepl-hook' is run, but yields an error if that hook
is not run in 30 seconds?

I spent some time trying to figure out how to do that using
`add-hook', `remove-hook', `catch', `throw', `unwind-protect' and
`sit-for', and then I realized that if I asked this question here then
probably someone would answer with "look at code for foo in the
package bar"...

  Thanks in advance!
    Eduardo Ochs
    http://angg.twu.net/#eev


P.S.: my reasons for wanting/needing that are here:
https://github.com/joaotavora/sly/issues/550