a modern ideal(1)?

I've recently been looking into the ideal(1) preprocessor -- it looks
like a neat little thing, declaratively creating pictures with systems
of equations. I was wondering what the status is on modern
implementations? I found the following github repo

	https://github.com/an-ideal-language/ideal

but I have been unsuccessful building it on a modern machine... (well,
I _did_ get it to build, actually, but I couldn't get it to produce
any output; it seems to hang indefinitely even after EOF.) If anyone
else would like to take a look and see what they can do (or point me in
the direction of a modern impl!), I would be very happy.

Another note: I recall now that the original reason I was looking into
ideal was because of the note about
_G3 - A Language for Typesetting Three Dimensional Graphics_
on troff.org. I have been even less successful tracking anything down
about this mystical `G3(1)` (at least with ideal(1), one can find man
pages and papers...) With how ideal(1) is based on complex numbers, it
makes me imagine a similar preprocessor that works in quaternions for
3d graphics :) (perhaps could simply be a prepreprocessor for ideal by
just doing some transformations to get the 2d projection of a 3d
object?)
-- 
S.