Every few years, someone tells me I should learn another language, and in recent years, there just is no desire in my mind to want to learn yet another language that is merely another way of doing something that I already can do elsewhere and the only way I will is if I am forced (that is how I used Go).
That said, I do see what you are saying. C++ for example has an “support every paradigm” philosophy, so whenever someone who has learned C++ encounters a language using a paradigm that C++ assimilated, there is a huge temptation to try to view it through the lens of C++. I also can see the other side too: “C++ took me forever to learn. Why go through that again when I can use C++ as a shortcut to understand something else?”. C++ is essentially the Borg of programming languages.
Based on his comment, I did not think that he is proficient in them, but that he has used them, which is fair enough, so have I, sans all the ones tied to either Apple (Swift) or Microsoft (C#).
I have some projects in Haskell just for curiosity's sake, and because what I wanted seemed like it would be nice in Haskell, and it indeed looks quite elegant to me, for this one particular project. Haskell is not a language I would use generally. OCaml is.
There are some languages in which I am extremely proficient. My best language is C, which is my favorite and I have used most features of every version of C from C89 to C11. My second best is probably either C++ or POSIX shell (although I have moments where I forget certain syntax and need to look it up, especially in POSIX shell for variants on variable substitution, e.g. ${VAR%%foobar}). I have used most features of C++98 and some from newer versions. My experiences with C++ have soured me on it, so I now try to avoid C++ whenever I can in favor of C and Python.
My first language was actually PHP 4.2.y, and I was fairly proficient in it, having spent a long time learning it while simultaneously writing my own code for a website as a teenager. However, I never once touched the portions describing objects/classes, namespaces or exceptions. Someone else at work writes Modern PHP code using Symfony and I have taken a peek at it. It looks very different from the PHP I knew because it uses the features I had avoided learning (and probably some new language features too), although I can sort of read it thanks to having learned those concepts in other languages.
I used SML/NJ and Java in college. Years after college, I modified an open source Android TV application written in Java to add some things I wanted, although honestly, beyond that I have not really touched either language. Give me an arbitrary application written in either to improve and I would have some difficulty, although I will probably be able to do it after filling the gaps in my understanding (and doing plenty of head banging if it is a large program).
I have used JavaScript for a few recent projects via electron/nodejs and I have done several small things in Python over the past several years. Each time, I only worked with the subset that I need. I am far from a master of either language that can understand arbitrary code written in them, but I am able to manage as far as my specific needs are concerned.
I could continue listing my experiences doing things in languages (like the time in college that I wrote some basic programs in FORTRAN 90 to try to learn it), but they really are not that interesting. It was often a project here or a small application there, and as I readily admitted, I only used a subset of most of the languages. For programming, a subset of commonly used bits is often all you need.
