New package: place-controllers

[Sage Gerard]

Here's a way to encapsulate places in a generator-like procedure: https://docs.racket-lang.org/place-controller/index.html

I ended up writing this to support a parallel build model, such that a single (apply sync (p1) (p2) ...) returns a value or status from a place, along with helpful context.

Source code is available at https://github.com/zyrolasting/place-controller

~slg