Not sexps, but better.
Quite a while back I have read about a system based on Scheme , called termite (I don't remember which scheme that was) that can actually sling live running code/closures across network and execute them remotely..
Boggles my mind even today.
Tcl has a library called "comm" [0] that lets you expose an interpreter over a socket and since everything in Tcl has a string representation, there's no need for a serialization/deserialization step.
[0] https://core.tcl-lang.org/tcllib/doc/trunk/embedded/md/tclli...
Erlang also has this capability built in. You can do all kinds of weird stuff with it, it’s great.
Probably this?
“Concurrency Oriented Programming in Termite Scheme”: http://scheme2006.cs.uchicago.edu/09-germain.pdf
Implemented in Gambit Scheme: https://github.com/FredericHamel/termite-scheme