[Jach]

Yeah I was pretty sure I've seen this in both Nim and Common Lisp, but don't compile-time macros in general allow for this? A comment even mentions source-text replacement with C functions. So it seems like the "jet" is just a type of macro that is formally specified to behave as a pure transformation...

[derefr]

If macros are "GOTO", a jet is a "COMEFROM". A programmer knows they're calling a macro, and expects that code to change. A jet, meanwhile, affects code that was written without knowledge of the jet.

[coding123]

It sounds like a aspect oriented programming.