ReasonML is an object-functional programming language created at Facebook. ReasonML lets you write simple, fast and quality type safe code while leveraging both the JavaScript & OCaml ecosystems.
In this full course from David Kopal, you will learn everything you need to know about ReasonML (aka Reason) and you will be able to start building awesome things with it.
You can watch the full video course on the freeCodeCamp.org YouTube channel (5.5 hour watch).