I recently had Codex convert an script of mine from bash to a custom, Make inspired language for HPC work (think nextflow, but an actual language). The bash script submitted a bunch of jobs based on some inputs. I wanted this converted to use my pipeline language instead.

I wrote this custom language. It's on Github, but the example code that would have been available would be very limited.

I gave it two inputs -- the original bash script and an example of my pipeline language (unrelated jobs).

The code it gave me was syntactically correct, and was really close to the final version. I didn't have to edit very much to get the code exactly where I wanted it.

This is to say -- if a novel language is somewhat similar to an existing syntax, the LLM will be surprisingly good at writing it.