Sounds right.

Additional examples at

https://github.com/louyx/aplus/blob/master/src/a/k.h

https://code.jsoftware.com/wiki/Essays/Incunabulum

How would you characterize that?

Heavy use of the C preprocessor and C defaults to embed a functional programming language. Language with a small number of core functions and ability to apply functions to lists of atoms. Aesthetically favoring short identifiers and minimal whitespace to create high semantic density. Eschew comments.