Programming languages and Frameworks to learn in 2015

I think reactive programming (such as RxJava) is quickly gaining on popularity these days and seems like a promising paradigm...

If you have the slightest interest in the issue of concurrency then you should study Erlang and Clojure. Since Moore's Law has largely faded, and we now gain speed by putting more CPUs in each server (rather than having the individual CPUs be faster) concurrency is an increasingly unavoidable aspect of programming. Joe Armstrong (Erlang) and Rich Hickey (Clojure) have both spent an enormous amount of time thinking about how to support concurrency in a programming language. Armstrong talks about a paradigm that he calls "Concurrency Oriented Programming". Armstrong's thesis is surprisingly readable and I recommend it:

http://www.erlang.org/download/armstrong_thesis_2003.pdf

Rich Hickey's video presentation "The value of values" is also a good overview of some concepts that are important to Functional Programming:

https://www.youtube.com/watch?v=-6BsiVyC1kM

Thanks for aggregating this. I'll be heading in the opposite direction, so that someone may be right if the majority turns out wrong. Just kidding.

Rails has allowed me to move from being a product/programme manager to start up owner / developer in six months. I've managed the development of products using PHP and .NET technologies, but when it came learning to code myself, Rails enabled me to learn and iterate quickly. Ruby is beautiful, and the Rails community is both prolific in terms of making the gems you need and responsive when you have problems. 12 months ago I was coldly agnostic about frameworks, I am now a bit of a fanboy.

Depends if you want something that's marketable now, or more if you're asking what's interesting learning for the future.

Django and Rails are still powerful in web development territory, but I don't find them particularly exciting anymore.

I'm quite interested in seeing where Go and Rust evolve to provide developer-productivity and performance at the same time. Previously, we've had these kind of splits where we have Ruby/Python/other at one end, and C/C++ at the other, and things in the middle have felt like compromises (Java, etc). I'm thinking we can get to a nice happy medium, once their standard libraries mature. Still, there's not a lot of job opportunities out there in these yet. But interesting!

To me, a lot of what makes a language usable is how big the standard library, and community libraries around it grow to be. So, for now, a lot of the cool stuff would require more legwrok on your end to make it work for certain applications.

On the UI side, JavaScript remains absolutely pervasive, but I wish there were clean alternatives that didn't require something compiling down to JS. It seems that Angular is going in the right places.

I'd be interested in people's takes on whether Scala/Clojure are no longer gaining any interesting traction or whether I'm wrong about that - there's still a giant ton of Java out there, obviously.

If you just want to hurt your brain in interesting and useful ways, functional languages can be great fun.