While I am working mostly with Elixir currently (as well as doing some maintenance of Ruby/Rails projects…) I am most excited about considering the possibilities of using Haskell as server-side language, where the higher-order (and in some cases dependent) type system is able to perform a huge amount of checking at compile time.
And on the other hand, I hope to build a WebApp that uses Prolog under the hood sometime. Mostly because I think it would be very interesting and I’ll definitely learn a lot along the way.