Sun Apr 7 11:12:52 EDT 2019

Tree vs. Path representation

Because of the flat nature of the I/O field, it seems simplest to
introduce hierarchy in the form of a path encoding, as opposed to
nested structures.

This relates to a pattern I've seen pop up in other places: if
hierarchy gets too arbitrary, it is often more convenient to switch to
a flat environment, and put the hierarchy in the keys instead.

Of course, both tree and path representations are isomorphic.  It is
merely a matter of convenience for the packing/unpacking code.