nim-esp8266-sdk VS ulisp

I went down many of those routes myself, though not the lisp ones. There's also TCL. But I've settled on Nim as my favorite for embedded (at least for a while). For the esp2866 Rust (or D) would be tricky. Nim can compile to C, unlike Rust which doesn't support the Xtensa architecture found on most esp chips. Not sure about D bit it seems unlikely to support Xtensa.

There's a Nim Esp2866 sdk: https://github.com/clj/nim-esp8266-sdk

I love his projects too. He's also the creator of uLisp.

http://www.ulisp.com/

Not CL, but there is ulisp (http://www.ulisp.com/) for microcontrollers, supposed to be really tiny, and there is Carp (https://github.com/carp-lang/Carp) which is without a GC so seems suitable for real-time stuff.

There's also ulisp (for Arduino projects etc.): http://www.ulisp.com/

This is larger, because there are functions for accessing peripherals, and the core is more standard lispy with 'caadr' et.al., and it has a compacting GC, so images can be saved as a compact blob.

You might consider uLisp, it's very Common Lispy for the memory constraints given (sans macros and splicing quote). And you can still connect to it and save an image. I've tried it and it works well enough. Here is the homepage.

Agreed - the interactivity is good. Lisp is close (have you seen http://www.ulisp.com/ - I can't believe they got into into that small a target!). Python is ok, but for some reason I don't use the REPL in the same way I do in Forth - I think calling functions is just harder somehow. Mostly is exploring valves from the Python REPL.