I mostly switched from MetaPost to Asymptote for generating my figures.
One thing that I found useful in MetaPost (or more specifically, MetaFun) was the debugging routines such as
drawwholepath which renders the details of a given path. This is may be used to determine subpaths for commands such as
buildcycle or just to analyse or refine a path coming from a library.
It seems Asymptote is not (yet) equiped with such debugging routines, so here is my attempt.
Here is a simple path, drawn normally and then with my debugging routine.