Be mindful that most of julia's geometry code is a wrapper of libGEOS (C version) and libGDAL, that means that you can't easy extend the algorithms, everythig is behind a black box on the C side. Source: I have worked in the field last year, I have a small patch in LibGEOS.jl .
So in other Julia geometry-related projects that may be true, but for this particular corner of the ecosystem the main author (Júlio Hoffimann) has actually implemented much of the underlying geometry and other code from scratch (to the best of my understanding) in pure Julia in a whole set of packages, including e.g.
Scanning the site see mostly points algorithms, the only mention of polygons is a textbook LibGEOS call, I see no network at all. And I see no smart manipulation of anything else than points, I see no subdivision of space, etc.
I have worked with it. It was just stating, very little useful code in it. Going back to the source code, I see they added a bit more.
A quick look around suggest that only one algorithm uses an indexing structure. Clipping seems limited between a convex polygon and a concave one.
The book is quite interesting, but it does seem like a lot of the underlying work is farmed out to GeoStats.jl, which doesn't really seem to use the same vocabulary I'd expect in other languages using PostGIS or Geopandas etc. For example, I don't see many mentions of Polygons or MultiPolygons when I search. However, I do find this page[1] which seems to define similar(?) equivalents. Can I expect equivalent geospatial joins/queries to be available? I don't see many mentions of the types that I would normally do, especially overlay operations[2].
