Very cool. I overall very much like both your library, and your presentation.

That said, I found the abbreviations initially confusing. For variable names and symbol/strings, maybe hold off until not the first example? For the functions themselves, can you do a non-abbreviated alias?

I also missed the `par` in `seq((...).par(...))` the first time. And, personally, I think `par([...,...])` would be clearer, and allow for some beneficial constructs - is there a way to allow both?

Particularly, I really admire the time travel aspects; that you can, what that means, and what allows that to happen.

It reminds me a lot of what I've tried to do (not as elegantly, so I might come crib from you!) with the pattern renderer in https://github.com/rangerscience/butterfly