I see this attitude in the corporate world and among people who are newer to programming a lot.

For skilled, experienced programmers, most mainstream languages become an implementation detail. You have to spend time learning idioms, footguns, and generally the way the language manages memory, but you absolutely can be great at 7 languages because they fundamentally do many of the same things.

I haven't hired people based on "their stack" in a long time, and it's been completely fine. Someone with skills can quickly learn your stack and be productive in it. I personally jumped on a project as a coder a few years ago having never written C# before, and I was productive in about a day. All the concepts were familiar, and the stuff I had to learn was mostly syntax.

Exactly. "If a person can drive a Honda, how well can he drive a Mazda?". Duh, just as well as Honda. And just like the natural languages, the more you know, the easier it gets.

   > All the concepts were familiar, and the stuff
   > I had to learn was mostly syntax.

This reminds me how I have learnt to program. I grew up in then USSR, we had no computers at our school but we had programming lessons. So I was introduced to all the fundamental concepts: variables, assignment, loops, control structures, etc. When I went to university I finally got access to the computer (Yamaha MSX). And then it was exactly as you say: "what's MSX Basic's syntax for this particular concept?".

If a pilot is only type-rated to fly an Airbus 320 he is not allowed to even try to fly an 737 nor a different type of Airbus. This attitude of "a car is a car, what can go wrong?" is deadly in some domains.

In my (corporate) role most of the people around me have over 20 years of experience in a very specific domain (manufacturing execution systems) and it takes about 5 years to train a new person. Having someone new productive in month is a dream for us, but it never happened.

If you can be productive in about a day, please explain why a pilot gets ATPL (airline transportation pilot license) after a minimum of 1500 hours of flight. Also please tell if you would board a plane where the pilot has 100 hours - that's an awful more than a day or even a week.

I know what a language ought to be able to do and where the usual foot-guns are. I haven't even attempted to really learn a language thoroughly since my first one (Perl—and yes, that's probably part of where my brain-damage comes from). It's all the same stuff, more or less. Understand pointers and how things like how OO systems are usually implemented, how stacks work, that kind of thing, and all the languages start to blend together.

99% of the pain in a new language usually ends up being the (often god-awful) tools, platform/SDK bullshit, and learning where the clearest path is incorrect (no no no, the official docs and tutorials say to do it this way, but everyone who knows what's what actually replaces that entire part of the language/first-party libraries with this other library developed & open-sourced by some other company, since the official way is obviously so terrible, and you just have to know that, or notice by reading other people's projects—ahem, looking at you, Android). The language itself is typically nothing.

This has worked out fine for me. It does mean I've gradually grown to hate languages that lack static typing. I don't want to remember or look up things when I can make a quick note and then let the computer remember or look it up for me. I thought that was kind of our whole thing, no? Having computers do stuff for us, when they're able?

I think you overestimate the value of being super intimate with any given language. Pretty much no language in common use is so different from the others that you drastically have to change how you express any given thing you're trying to do. Knowing concepts and when and how to apply them is more important in my considered opinion.

In my opinion, if you're hiring for an expert in a specific language, you're not hiring a software engineer, you're hiring X language developer or X language software engineer. The language needs to be explicit in the position listing and perhaps even job title. That's fine if that's what you want but be specific about it so you don't waste people's time looking for a language specialist when most people anymore are generalists that have all sorts of knowledge distributions for any given set of technologies but can most likely adapt and learn to fit your distribution of technology given just a bit of time and opportunity.

Modern development requires juggling too many technologies for most people to specialize in a single language unless their career goal is to niche themselves to that language.

Someone doing webdev fullstack for more than 10-15 years will know at minimum ES + (PHP/Python/Ruby/Java/Go...) + SQL + HTML/CSS and a few utility languages.

So at least 4. If you combine webdev with something low level/embedded, you need at least one systems language, so you're at 5 languages you need to be proficient in.

Add one hobby language or a second web backend or systems language, and you're at 6 major languages.

7 is a lot. But 5 is plausible to be proficient in for someone who switches between webdev and lowlevel stuff to not burn out, or has a FOSS hobby.

I've shipped production code in 17 different programming languages. I wouldn't say I'm proficient in any one of them, they are all just tools to solve a problem and the knowledge of language specifics comes and goes. Need to hyper-optimize a DB query on an Oracle RAC cluster? PL/SQL. Need a shader? GLSL works fine. Need a webpage? HTML/CSS/JS. Need to build a 7' long flying robot fish? C. Programming languages are just tools.

In over 20 years of working in IT I never found a single webdev-type of person that can write an efficient SQL query by himself. Yes, most are able to write a query to bring the correct result, but I saw way too many cases where the perf test on a database with the expected production volume was running in completely inacceptable times and the developer had no idea how to fix that; for each version of SQL perf-tuning is very specific.

Also proficient != expert. I met enough developers that were brilliant in their work to be convinced that 5x developers are not a myth, but they are real, while rare, occurrences. For me a senior developer in X knows the ins and outs of that X to the level that his code is an order of magnitude better in term of efficiency, performance, productivity and security. A regular developer can be just proficient, but it is not what I wrote about.

As a hiring manager for over 15 years I prefer people who can pick up a language based on the need. Good problem solving is language agnostic.

It is an option, but how fast will they be very efficient? It takes years to master something and some people, not all, need to have that mastery level.