Alternative models

[mgree]

~Lazy loading (scan but don't parse into structures until demanded).~ #50

Ahead-of-time mappings (literally build/unbuild FS).

Use 9p, per Jay McCarthy. Or use the Bento FS thing?

[mgree]

~Use the visitor pattern to make Nodes implicit. This is orthogonal to lazy loading. (Can we make this optimizations on/off switches, for evaluation?)~ Since Nodes are single level, this is morally what we're doing already. (The visitor pattern would have us call some particular callback rather than reifying the Node structure. That's tiny microbenchmark territory.)

There is an opportunity for savings, though: can we reduce the copying/vectorization of maps?