What is wrong with moving from one tech stack to another?

^{Aug 1, 2024}

Recently I heard a discussion about whether companies should hire people with different tech stack experience than a company work with?

Big tech often claims the tech stack doesn’t matter - just test algorithmic thinking in pseudocode. And it makes sense: with enough resources, they can quickly onboard devs to new frameworks. Because honestly, learning new syntax is just part of the programmer day job.

As a result I regularly see Java smell code written by former C/C++ developers that looks like this:

private void getUserIds(int[] result) {
    ...
    for(int i=0; i<=N; i++) {
        result[i] = users[i].getId();
    }
}

Here’s an example of a function with side effect. Have you seen such code? Have you written one? Someone calls this evil. These C developers used to write this, because they can’t do that differently in C.

So C programmers learn a Java syntax, learn the Spring framework and start writing the same procedural code as they do before. But they haven’t learned a new paradigm — and that’s harder than just learning a new library.

Or is it not their fault? Java doesn’t enforce a concrete paradigm — while it’s supposed to be object-oriented, in reality, it’s a hybrid: you can write functional or procedural spaghetti also. So perhaps don’t blame the programmers — blame the language’s design?