[urbit]

Perhaps it makes a bit more sense if it's explained that the original goal was to keep the whole codebase (outside of the C support layer, which adds no semantics) at 10Kloc. Unfortunately this is now rapidly slipping toward 20.

Of course, Kloc is a deceptive measure of algorithmic simplicity in a functional language, if compared to procedural. Also there is about another 15Kloc of C in the interpreter and another 10K that wraps an event layer on libuv.

Bear in mind that Urbit can also be seen as an ACID database on the log-and-snapshot principle - events are transactions. You can of course export application state to some other storage system, but you don't have to. (If you change the source code, your app reloads - you do have to write a function that maps your old state to your new state, though.) So there is a lot of strange futzing around with mmap at the bottom.