I noticed that the C++ code has no comments whatsoever. Why would they do that? The code is clear enough and you can read the papers to figure it out or do they clean up comments before releasing internal code to the public?
I suspect it's the latter, since code not initially OSS likely has some references to IP, or org structure, some crudeness, etc. Probably easier to remove it all than rewrite.
Adding comments back in would be a great start to contributing to OSS.
I took bdcravens' comment to mean it'd be a great project for someone who wanted a way to start contributing to OSS, not a suggestion that Facebook wasn't contributing.
Like whafro said, that wasn't what I was trying to suggest. Never meant to denigrate their contribution, only saying that parts that were never intended to be open (like comments) were probably removed rather than rewritten, which is perfectly acceptable and consistent with their great open source contributions.
We usually strip the commit history since it's hard to audit the history for confidential info, but we don't normally remove comments when open-sourcing things. I'm not sure on the specifics of this case though.
