I have the beginnings of a command shell for the Mu computer, which is built up from machine code and designed to be taken apart.
https://archive.org/details/akkartik-2min-2020-10-27 (video; 2 minutes)
A postfix shell is promising in some ways, but I'm not sure how to support concurrency. Currently each operation completes before the next. I could allow "pipe stages" to continue to share data after they drop file handles on the stack, but there are problems: how often we refresh, how we kill processes from past refreshes, how we visualize file handle contents. Comments and suggestions appreciated.
Previous episode: https://discord.com/channels/239737791225790464/404399251276169217/768366407871102998
Main project page: https://github.com/akkartik/mu