Missing adapter: loop?

[Charles Oliver Nutter]

It seems like there's a need for a looping adapter, since there's no
way to feed an existing handle back into its own call chain easily (or
am I wrong?):

loop(test, body)

I've been thinking about something John said about making a threaded
interpreter using all handles, and trying to work through what it
would look like. I'm having a lot of fun composing handles, and would
like to try something more complex with it. Loops seem like a
necessary addition?

- Charlie