If you have $200k "python engineers" on the payroll who wouldn't jump at the opportunity to do some additional Erlang, maybe it's time to reconsider your hiring practices and that is the real cautionary tale.
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 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.
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.
There was at least 1 really large error that slipped into production because we were mocking an untyped service incorrectly (a mistyped property name), and the test passed, but prod exploded. It was embarrassing, and I certainly would have caught it with more mypy discipline, but overall the pros outweighed the cons.
At big companies that use mypy, however, this is problematic. If teams only define types for the straightforward parts of the system, then the types become less useful, especially as the company scales. From what I’ve seen, individual teams use an all-or-nothing approach with MyPy, so it’s unusual for an individual dev to sparsely type anything.
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 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.
And no, it's not the same. Not even remotely. The only thing that helps with are quick and easy deployments.
The thing which makes maven special is the ease of producing artefacts for deployments, not the final step of starting it up on the server.
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.
That is only if it's actually useless. I haven't programmed in haskell for many years, yet I am very glad I did. It was hard at first, but it made me think about code, data and transformation from a different perspective, expanding the repertoire of paradigms, regardless of which language I code in.
YMMV, but personally, I'd much rather hire or work with someone with 3y java + 1y erlang experience, than just 5y java experience. In general a polyglot rather than monoglot, especially if it's a different coding paradigm. Nevertheless, I may not actually want them coding random bits of work in erlang or whatever random language.
I've almost exclusively worked on the usual procedural /OO languages professionally (java /c#)..I like to experiment and I've picked up a bunch of languages along the way (perl, python, coffeescript, f#, nim etc).. And its usually because I want to see what's different and spend enough time to do something useful (but not large) with it. Also, it helps you become a better programmer IMO. otoh, if I'm hired for my skills but then have to work on js( don't actually like the js eco system) or haskell (I gave up after trying and I doubt I'd become very good at it anytime soon if I were forced into it) I'd be not happy either (and IMO, with valid cause that doesn't reflect on me or my abilities)
They can put only "Python" on their résumés, right?
For example, I wouldn't want PHP or Fortran on my resume, and, consistently with that, I avoid them. I don't have an opportunity to actively avoid them, but that defense mechanism would leap into action, if called upon.
However, I know a thing or two about these; I'm not simply applying "meme-based reasoning".
Would you want to pass on Lisp because of the ramblings of a rookie web developer with no Lisp experience? That's what you might do if you believe the "Lisp Curse".
Ah, sure they might be willing, but as a lead I'm not willing to invest in it.
1. I'm not sure I want someone who's got 4 weeks of experience in a language working on system critical infrastructure. Pick your time, does it take 6mo?
2. They have existing work, learning and working on an entire new language _AND_ new project is a huge task. Especially for non-trivial projects.
We could, but in our case it was a better engineering decision was to retire the old system and move on.
I have made mistakes like that (introducing monads/future and making the team learn guava) and I still regret it. Its not to say futures are useless - there were a lot of async logic in the codebase and futures solve a real problem, but its not clear if the benefits outweigh the cost.