There has always been an interest in these languages. What's changed is that using a functional language no longer cripples you. That is, the rise of service-or

There has always been an interest in these languages. What's changed is that using a functional language no longer cripples you. That is, the rise of service-oriented architectures, horizontal scaling, javascript, and REST APIs mean that it is no longer suicide to build your product using a functional language. 20 years ago you needed to write desktops apps, so you were limited to C/C++. Then 15 years ago you needed access to java libraries, and the only real JVM language was Java. Now, you just need to build a service that speaks HTTP, so you just need a HTTP server, a HTTP client library, and a database adapter. That means you can build your product in any language you like, and not lack the ability to succeed. CircleCI is written in Clojure. We communicate with all our vendors over simple REST APIs - it only took a few minutes to write our own client bindings for Stripe and Intercom.