Back in the day people would balk at hiring Python programmers saying, "there are so many more Java programmers", and I used to say, "Why would you hire a Java programmer who was unwilling or unable to learn Python?"
Same logic applies here: Why would you hire a Python programmer who was unwilling or unable to learn Erlang? (Especially if you're going to pay them to do it!)
If you can't switch languages you're a kind of technician not a programmer.
FWIW, having done it professionally for ~15 years I'll never write another large project in Python again. Erlang's runtime is so much better than Python's it's just ridiculous. I feel stupid for not realizing this sooner.
I get being interested in Erlang if you're doing Python. But interested in doing Python as a Java dev? Probably not.
And no fat-binaries. Nor self executing binaries. It's just as old and having em basically just boils down to enforcing conventions. But nope, nothing. There have been attempts by some such as shiv, but really... None are even remotely as usable as maven is.
I've been a happy Python programmer for over fifteen years, so this comes from a place of love and respect.
Beyond roughly 150k LoC you start to run into difficulties keeping everything straight over time, especially if you use a lot of indirection or other magic. The aspects of the language that help you go fast when you're prototyping (is "RAD" still a thing? Rapid Application Development) start to trip you up when the codebase matures. There are a lot of fancy footguns in Python that catch you if you stop dancing.
Tooling is getting a little better (MyPy, et. al.) but at the same time the overhead of adding explicit type information erodes the advantages Python has over, say, Java or Haskell.
Your example of Java to Python doesn't represent the gravity of switching from Java to say Erlang or Haskell. You assume someone says no because they are unwilling or unable. We are unwilling, sometimes, because of the opportunity cost we have to pay for your fuck up.
Why would learning a new tool narrow rather than widen your opportunities?
It's not like you forgot all you know about Java.
Languages and specially the tool chain and the way of doing things around them evolve. If you spend like 5 years doing something else and come back to it, you'll find things have changed a lot. You may argue that it's easy to relearn this. But from a job perspective, the guy who has been using the exact same tech stack in the recent years will often be a better bet than a guy who wrote Java in version 1. This is very true for C#. Syntax, design principles, tools, method of deployments all have changed rapidly. Professionally, you want to be as up to date as possible in the area you worked in or you get rusty. You can learn new things on your time for their own utility. Flushing down 40-60 hours a week on a useless piece of knowledge is bad all round to me.
The moment we can get rid of it, you bet we will. But it's much easier tearing it down when you understand it enough to discern designs driven by the limitations of the tech vs requirements for the product. Black box ground up replacements are hard and expensive compared to ports. Also, thankfully it's Python and nothing something more difficult/complex.
At the end of the day, it's a job, and there's an expectation of professionalism to do what's necessary. A lot of people on HN like treating tech jobs like a paid hobby which I think is detrimental to career development.
I have met lots of engineers who are smack dab in the middle of the flock when it comes to tech stacks, or even _behind_, but they were more than capable. Hire for what you need. But what you think you need and what you actually need is probably not know to you.
