I don't know anything about learning Elixir, so, cannot help on that specific topic.<p>But, here's how I conceptually think about advancing one's understanding in programming.<p>First, you can aim for breadth or for depth of knowledge. So, learning another language is, in itself a kind of "advance". However, for depth, you'd usually want to pick a specific sub-discipline in programming and concentrate on that. You will have better luck with choosing theoretical disciplines, because those usually are rooted in math, and so have longer history and more systematic approach. The more "practical" aspects usually follow the arc of having an introductory course (at best) with the next learning stage being an "area of active research" (also, the intro course would typically be bad).<p>To give you an example: in college I became interested in regular languages. So, I was looking to expand my knowledge on the subject. Out of all things that I could dig up on regular languages two seemed most appealing: approximation of context-free grammars with regular languages and equivalence between generating functions and regular languages. In a short while I realized that I don't have enough of mathematical background to go after the generative functions part, but the approximation part turn out to be fun and interesting. I was able to dig up some papers and even try my hand in doing something with the concept.<p>You'd have similar success if you went after types in programming languages. There are plenty of publications, and you will have multiple steps ahead of you before you run up the wall of "area of active research". My journey down that path started with Benjamin C. Pierce's Types in Programming Languages.<p>Another direction you may consider is to try to generalize your knowledge. For example, of programming languages. In this regard, I find the book by Shriram Krishamurthy, Programming Languages: Application and Interpretation to be a good introduction to the theoretical side of crafting and evaluation of programming languages.<p>There are, also, unfortunately, some areas where a lot of programming work has been done, but very little learning material is available, and, especially nothing deep has been produced. For example, if you want to go down the system programming route... there are books, that's true, but the level of generalization leaves a lot to be desired. It's often boggled in all kinds of "practical advise" and very concrete examples based on Linux Kernel code long ago replaced by something else (or worse yet, but original Unix code etc.)<p>Or, even worse, if you consider fields like testing. Or even GUI. It's surprisingly common and yet surprisingly without much analysis or structure.