back in the day when we wrote enterprise bullshit in common lisp (!), we had put together a proof of concept where we used delimited continuations to write business processes.

business processes were written in basically full common lisp with very few limitations, and with a few extra primitives to use (and 10x slower due to being interpreted, but that didn't matter at all). when a process reached a point where it was waiting for some external event (e.g. displaying a GUI for a user and waiting for their feedback, or sleeping until a deadline), then it got serialized into the (SQL) database.

it was pretty cool! when a user logged in, there was a list of processes waiting for him that he could click to see and interact with. all this with the transactional guarantees of the sql backend because the business objects were also stored in the same database.

https://github.com/hu-dwim/hu.dwim.delico was the continuation lib, hu.dwim.perec was the object relational mapper, and hu.dwim.serializer was used to turn CL objects into SQL blobs (with some properties extracted as reified SQL schema elements to be able to search for the suspended processes).