I've been thinking a lot about source code transformations as a possible key for maintenance in the "future" of programming. Its interesting to see that the preprocessor, which is a source code transformation itself, makes other source code transformations much more difficult, if not intractable. I'm wondering if this inherent to any macro system since they are not bijective.

Two possible directions I see away from macros which would play nicely with source code transformations are un-macros and layers of languages.

Un-macros would take source and display it in the condensed form only for human reading -- this takes away from human writing power of course, which may have to get pushed into the editor. This could also allow for automated pattern discovery.

Layers of languages would look similar to Racket's #lang concept and current macro systems, but without the ability to escape back into the parent language. This creates a new language on top of -- not mixed into -- the parent language.