[codeflo]

Think about applications, not one-off scripts. It should be easy to always stay on the latest language version, with good tooling to migrate your code, and importantly, the ability to do it piece by piece. (Python 3 was all-or-nothing for the entire ecosystem.) Also, many migrations are trivial in practice, like renaming an identifier to avoid the new keyword.

What this gives you is high confidence that when inserting a few lines somewhere, that fancy new for loop simply works. No need to scroll to the top if the file and remember which exact release of the 27 in the last year introduced the feature.

[doomvox]

> It should be easy to always stay on the latest language version

With perl you can upgrade your language version whenever you like, and do it reasonably safely, because there's a lot of emphasis on backwards compatibility.

Perl may actually have a "always gimme the latest features" option, but I don't know what it is, because things like that aren't really that popular in the perl world-- we want old code to keep working the way it always has.

[badsectoracula]

Yes i know, in fact i thought about it when writing that line but i thought it'd be obvious that the issue still remains, especially if said files are too big. It might be easier but you are not really solving the problem as well as opting in to the new functionality when and if needed.

[codeflo]

I hope we can agree that Python 3 was qualitatively different because all of your libraries had to migrate first.

Now, your new argument depends on how hard it is to migrate a single file. If that’s sufficiently easy, you simply do it. Migrating to the last Rust edition, I had to fix maybe a handful of things in an entire crate; most files didn’t have to be touched at all.

[badsectoracula]

Certainly, Python 2 to Python 3 was harder due to all the dependencies and having to convert the entire program.

My argument isn't really about migration is about not having to migrate if you don't need the features while not losing anything - by opting in to the new features/changes you can use whatever you want without wasting time on changing your code to do the same stuff just in a different way (unless you decide that this different way is actually better and worth doing, but that'd be your choice and not something indirectly forced on you by the ecosystem you decided at an earlier point in time to rely on).