Years is an exaggeration. I happened to ride the popularity wave of both Go and Rust at their respective moments. I've seen a lot of programmers, good to mediocre-bad learning a new language on the job. The range is between a month and three months maybe. It's really not that big of a deal.

> Years is an exaggeration

Not necessarily when it's not your job, but it depends on what level of comfort / ease we are talking about.

A relative who is a physicist and who started with Fortran recently switched to Python. They told me it took them around 3 years to be as comfortable as before.

Now, I suspect they were very comfortable with Fortran to begin with, and if they programmed a significant amount of time everyday, they would have been up to speed way faster.

(They also said they would not go back to Fortran)

My wife is an "RSE" (research software engineer), she's an MD by training, but doing some programming for research. She's been in this role for about two years now, and she did maybe another two years of Python programming prior to that in a similar role.

She still doesn't feel comfortable with Python (or any language) and often needs guidance / help. Mostly because in this role, the amount of programming is really minuscule, and the expectation isn't that the programmer develops a useful application or library well-integrated into the larger ecosystem of applications or libraries. Rather it's that some research can sift through the data they've generated and publish on that.

The instances of "re-education" I was talking about were quite different: those were "programmer-first" people. In this capacity, they might write in a month more code than what what my wife wrote over the last four years, they are also expected to build a lot more complex (in terms of organization and integration) software.

I don't consider RSEs or similar roles to be professional programmers. These people typically have terminatory degrees in fields other than CS, but often no formal training in CS. They also rarely see their own goals in becoming as good of a programmer as they can, their evaluation is typically based on results that programming might help to bring about, but, in principle, isn't really necessary for. Sort of how you wouldn't call every programmer a "professional mathematician", even though writing programs is a kind of math, as is eg. checking out customers at the supermarket.

So, while someone like that might need years to adjust to a new language, OP seemed to have in mind professional good programmers. I think they even had another bullet point for hybrid scientist-programmers.

While I think you're correct that goals and roles may be different, on average, for the scientist-turned-programmer trajectory, there are plenty of RSEs who come from the opposite direction, i.e. strong programming background, but picks up the problem domain on the job.

Source: am RSE. And I will also say, a few of the scientists I support are among the best software engineers I have ever worked with, despite caring about code only insofar as it can help answer useful questions.

> A relative who is a physicist and who started with Fortran recently switched to Python.

Fortran is considerably simpler than Python, though. No metaprogramming. No functional programming. No objects. Etc.

Fortran is very simple though, more like Go or Java than Haskell. A C developer could pick it up in a week or so just reading the ISO spec, someone else might take like three weeks?

It's basically C with nicer syntax, and some QoL features.

I agree, Fortran is easy to learn, and it's a pretty small language so you can keep it all in your head. The part about Fortran that I find hard is the "culture" around it. There are styles of programming in Fortran that just don't work with my brain. Just like the "Java culture" of extreme abstraction (i.e FactoryFactoryBuilderHelper classes) bothers me too.

I can start a fresh Fortran program and write it out pretty quickly (though I do miss native dictionaries), but when I have to collaborate with an old-school Fortran programmer (especially one trained on FORTRAN 77) it's pretty tough for me. I have to reprogram my brain to think in that style/culture.

I tend to do most of my high performance numerical stuff in Numpy since it defers to the Fortran libraries for the hard stuff. I haven't found any properly written vectorized code get bottlenecked in the interpreter.

Fortran is simple enough to be used by dumb physicists. At its core it is a standard procedural language, like C with a lot less footguns and much more user-friendly. Its object-oriented parts have some strange syntax, but are otherwise unsurprising. There isn’t any step like when starting something like Lisp or Haskell.

It would definitely not take years to get on top of it for anyone who knows a bit of programming.