The standard response-- especially, I think, in popular books about Lisp and functional languages-- is that learning a new language helps you think and program

The standard response-- especially, I think, in popular books about Lisp and functional languages-- is that learning a new language helps you think and program better in other languages. My own experience supports that idea, but not strongly enough to "justify" the time I've spent investigating other languages. However, I don't worry too much about justifying the time, since it's just something I enjoy doing. From that point of view, I would say that if you enjoy learning Lisp, go for it. If as a hobby you brewed beer, or biked, or read Homer in the original, or played with your kids, would you feel bad that you weren't using that time to study Ruby and Javascript? The only counter-argument I can think of is this. How many personal projects do you have under way? Could you be running into a problem where you start many projects but finish none of them? In that case, you might want to dig into the root causes of that. But it would have nothing to do with learning new languages-- that might just be a symptom of a problem that really might have something to do with "pointless" effort.