Important to being a great developer. Languages and tools are interchangeable. It's the basics - the ability to problem solve, learn and adapt to new environmen

Important to being a great developer. Languages and tools are interchangeable. It's the basics - the ability to problem solve, learn and adapt to new environments that are truly important and timeless. Sure, being exposed to a new set of languages and tools can have some start-up penalty. But if it takes someone more than a few weeks (< 3) to be good at Scala, Ruby, Python, etc then there is something wrong. Running through a complete tutorial and solving real problems on a real codebase over a couple of weeks should be more than enough time to become proficient with a specific language if you already have the skills of being able to problem-solve. Don't confuse choice in your ecosystem of tools for quality. Just because there are tens of thousands of libraries for Java and .Net doesn't mean they are all good or that you can automatically choose the good ones. The beauty of a more recently popular languages is that smart people tend to be attracted to them and, in my experience, they tend to create better quality libraries and tools, even though they are less of them.