Besides the nonsensical "advantage over S-expressions" statement in the README, the biggest issue I have with this is that Mark maps only to JavaScript, not to other languages where dicts/maps/hashes and arrays/slices/lists are two different things. Makes me wonder if it just has not occurred to the author that there are languages != JS.
If all other languages have no problem supporting XML, they'll have no problem supporting Mark.
It just that in languages like JS and Lua, where an object can be an map and a list at the same time, they'll have the convenience of mapping a Mark object into just one object, instead of many.
Another way to support Mark in other languages, is just to use map for both properties and contents. E.g. in Java, the key in map can be integer. Of course, the performance will not be as good as primitive array. But it can be one man's quick-and-dirty solution.
General JS arrays (not those TypedArrays) are actually maps indeed.
