> One system I work with exposes a CLI. The whole system is written in C, and the CLI is basically just a frontend for a bunch of commands that take in [int argc, char argv]. It is, to misquote Greenspun's tenth, an ad-hoc, informally-specified, bug-ridden, slow implementation of a proper REPL.
Sounds like a poor man's execline:
https://skarnet.org/software/execline/