I’m mostly working in Java now. I’m proficient to the degree that I can solve most things without looking for reference online. I think that matters most to me.

Being proficient isn’t about getting something right the first time, it’s about how easily you recognize something as wrong and knowing how to get the knowledge to fix it. Under that definition I rate myself 5/5 if I’m not trying to be humble or sorry about tiny details.

What helped me a lot with pushing deeper down into the language innards is to have people to explain things to.

Last week, for example, one of our students asked what closures are.
Explaining that was no problem, I was also able to differentiate them from function pointers, but then she asked what in Rust the traits/interfaces Fn, FnMut and FnOnce did (which are implemented by different closures).

And yep, she struck right into a blank spot of my knowledge with that.
I have enough of an idea of them to just fill in something and let the compiler tell me off when I did it wrong.
Even when designing an API, I’ve worked out that you should start with an FnOnce and only progress to FnMut, then Fn and then a function pointer, as the compiler shouts at you (basically they’re more specific and more restrictive for what the implementer of the closure is allowed to do).

But yeah, these rules of thumb just don’t suffice for an actual explanation.
I couldn’t tell you why these different traits are necessary or what the precise differences are.
So, we’ve been learning about them together and I have a much better understanding now.

Even in terms of closures in general (independent of the language), where I thought I had a pretty good idea, I had the epiphany that closures have two ways of providing parameters, one for the implementer (captured out of the context) and one for the caller (parameter list).
Obviously, I was aware of that on some level, as I had been using it plenty times, but I never had as clear of an idea of it before.

I got pretty good with BASIC back in 1983.

I’ve been using c# since .net 2 which came out around the turn of the century (lol)

I’d happily call myself an expert. I can do anything I need to and easily dive into the standard library source code or even IL when needed.

But even then there are topics I could easily learn more on particularly the very performance focused struct features and intrinsics.

I’ve found LLMs to be super useful when you have a very specific question about a feature. I use bing ai at work so it sources all its answers and you can dive into the articles for more detail.

Programming is a never ending learning journey and you just have to keep going. When you get something you don’t fully understand to a deep dive there are always resources for everything.

Knowing the footguns in your language is always useful. The more you know, the less you’ll shoot your foot.

I think my job requires me to work in too many different areas. So although I can work in several languages and dev stacks, I am probably only a 2 or 3 or less out of 5 in all of them. However, network and server infrastructure, and cybersec/opsec I am probably more in the realm of a 4-4.5.

I’ve been using Scala professionally for 3 years. I don’t know what I’m doing most of the time because we have a ton of implicites and monads and extension methods. I just know the general idea and can get where I want by reading types.

I’ve been creating a language for fun for nearly 6 years. I often don’t know what’s going on under the hood because it’s somewhat complex. I think this is normal for every language. You don’t have to know everything to be able to use it. You don’t have to write blog posts once a week about the language subtleties you found.

I’ve been writing code for 25+ years, and in tech for 27+.

I’m a novice at all languages still. Even though they tell me I’m a Principal Engineer.

There’s always some new technique or way to do what I want that’s better I’m learning every day. It never stops. The expectations for what I consider to be good code just continues to climb every day.

After almost 12~15 years of programming in C and C++, I would give myself a solid “still don’t know enough” out of 10.

I have no fear of implementing anything I’m asked to in typescript go rust java c# f# or nix… They’re all the same tool just kinda different in some places.

Good enough to make my own things or mod things.

But not good enough to get a job as a programmer.

novice still learning everyday

I’ve learned a lot by breaking things. By making mistakes and watching other people make mistakes. I’ve writing some blog posts that make me look real smart.

But mostly just bang code together until it works. Run tests and perf stuff until it looks good. It’s time. I have the time to write it up. And check back on what was really happening.

But I still mostly learn by suffering.

I don’t think your question relates to the language as much as to the platform. The language of choice is somewhat irrelevant and what you care about is what actually happens under the hood.

For the likes of java and go you want to have some understanding of what runtime does for the memory allocations and how their GCs work. For python you sometimes end up in the spots where you need to understand what limitations the GIL imposes (even more important now that they are trying to get rid of it). When you run C (or C++ or Rust) on the embedded hardware it really helps to understand what exactly bit flipping does in specific registers and what DMA means for how you write your code.

You don’t really have to know it all. You can absolutely write code without caring about anything of that and I know plenty software engineers that do. Some people write amazing functional things in java without ever questioning what it does to the machines and what resources you need to run it.

If you start questioning it, that will only expand your understanding. It’s not a lateral move from e.g. C to Rust where you need to learn a lot to write your code in a memory-safe way, it’s a movement deeper into the stack and what you learn there will be applicable to any language you use for this stack.

Answering your question: I always feel bad about not understanding some low-level concept. I have stacks of MCU reference docs lying around, printed, highlighted; I have archives with sample code, and hand-annotated CMSIS reversing notes. Embedded world is hard because you can’t just know C and be done with it. You have to know the hardware, too.

Here’s my advice for you. Make notes of things that you learn from people smarter than you. Create a web of those notes and see where your gaps are. Then, work on learning something in those gaps in particular and see if you can make a blog post or something of your own. When you share what you learn you become one of those people with deep understanding that others look up to. There’s always someone struggling with something that you either know or know how to figure it out.