If you follow online discussions of programming languages, you’ll occasionally see articles about language X “dying”. It is, however, a bad metaphor, because the “life cycle” of a programming language is different from single biological units, of which you can definitely say at some point “He’s not pining … this is an ex-parrot!”.

Once a programming language is widely deployed, it simply won’t up and disappear from one day to the next. Too many people and companies depend on it, and replacing it is difficult enough, that the “switching costs” will keep it in place for many years. The obvious example is Cobol. This effect works in favor of languages that are not “the new thing”, and means they will probably not truly cease to be used for many, many years.

On the other hand, it’s also pretty easy to tell which way the wind is blowing and get an idea of what’s hot and what’s not. Java got hyped a lot in the past, now it’s Ruby. Scala is beginning to get hyped some, so is Erlang. Careful observers can spot the rise of languages as they hit the early stages of the technology adoption lifecycle.

By paying attention to what’s going on in the wider world, it’s also possible to see when languages are used less and less for new projects, and solely kept on for the legacy systems. I think this is what most people mean by “dying”, but of course it creates confusion, because it’s clear that the language is still utilized. In some cases, I think it may be possible that a language continues to be more widely adopted, yet still seems to lag behind, simply because other languages are being adopted at a significantly higher rate.

So what it’s really about is two factors: how widely deployed is the language in any given moment, and, perhaps more importantly, the rate of adoption – is it accelerating or slowing down? Are more people jumping on the bandwagon, or is the language being used less by innovators, early adopters, and new projects?

You need both those coordinates to understand where a language is at – it may be huge but declining, small but on its way up, or a niche language that never achieved widespread usage that isn’t catching on any more. The last one is the one you’d probably want to be wary of. The first two will probably be ok as long as you understand what you’re getting, and the type of user or organization you are matches where the language is at in its lifecycle.

I think that perhaps those interested in discussing these things seriously ought to find some good terms to use. “Forth’s rate of adoption is declining” doesn’t sound as exciting as “Java is dying!” though. “Fortran’s diffusion is decelerating” doesn’t have much of a ring to it.

Any other ideas?