Folly
An open-source C++ library developed and used at Facebook
...In particular, it's often a dependency of Facebook's other open source C++ efforts and place where those projects can share code. It complements (as opposed to competing against) offerings such as Boost and of course std. In fact, we embark on defining our own component only when something we need is either not available, or does not meet the needed performance profile. We endeavor to remove things from folly if or when std or Boost obsoletes them. Performance concerns permeate much of Folly, sometimes leading to designs that are more idiosyncratic than they would otherwise be (see e.g. ...