Facebook's Flow + CoffeeScript?

[taoeffect]

Types are very important for many categories of code, especially where security and reliability and some modicum of "provable correctness" is needed.

So, apologize if this is reviving #1852 somewhat, but new developments suggest new possibilities, like somehow combining CoffeeScript and Facebook's Flow. Would be super-duper awesome (and it can be an optional thing, where only those who want/need it would use it).

[vendethiel]

duplicate of #3743