Reason is a new developer experience by Facebook built and championed by the same people behind React. Based on OCaml, it offers powerful type-checking, incredible tooling, fantastic performance, and truly unbelievable reach (as in you'll be sceptical that it's possibly true). Full-stack apps in one language, from hypervisor unikernel to clients written in React (or ReactNative) - As easy as JavaScript, as delightful as Elm, as powerful as native, and with unprecedented reach - we're finally entering into an age of Reason.