[bluGill]

The cost is not paid today, but in the future when whatever you choose is no longer supported. If you write in something like C++ or Java running on Linux or Windows I'm confident that in 20 years you will find a tool that can build your code for the latest computers (not just the compiler, but the other tools as well). Of course Python 2 is a perfect example of why even the highest confidence choices may be wrong.

Rust is starting to look like it will make the jump to likely to be around for the foreseeable future, but only time will tell.

Of course just because you can build it doesn't mean it will work. I know of an embedded system where the 16 bit CPU went obsolete and they discovered that the C code was not 32 bit safe and worse it relied on the timing of the one CPU it was written for (though not so bad as to have to turn off compiler optimizations). I know of a product written for X11 that is porting to wayland. Keeping code running for decades is a hard problem - and one that many fail to understand. (nor do they need to - the web site you do today will need a major rewrite to fit the latest UI fad no matter what you do)

[filoeleven]

The other two languages GP mentioned, Elixir and Clojure, run on the BEAM and Java virtual machines respectively. I can’t speak to BEAM/Erlang, but your confidence that the JVM isn’t going away should remove any concerns about Clojure being supported in 20 years. It’s just a Java library, and has the same conservative approach as Java of ensuring backwards compatibility.

Clojure won’t necessarily live as long as the JVM does, in that the language could someday be abandoned, but support for its hypothetical last language version won’t be somehow removed from the JVM.

[bluGill]

> support for its hypothetical last language version won’t be somehow removed from the JVM.

Why not? Python2 is a good example - if they make a JVM2 without the cruft and then a transition they will leave behind those that don't transition. Of course that is the worst case and I'll admit unlikely.

(also the JVM isn't very relevant to me because I work in embedded systems without a JVM)

[filoeleven]

You wrote above:

> If you write in something like C++ or Java running on Linux or Windows I'm confident that in 20 years you will find a tool that can build your code for the latest computers

What I wrote was based on your confidence in Java (the language) being around in 20 years. One of Java’s core features is backwards compatibility. Clojure’s implementation will continue to work as long as Java (the language) itself exists. There’s too much business depending on old Java software for the language to break like Python3 did.

Clojure is also a hosted language by design, and has been ported to JS, .NET, and BEAM (though maybe not completely on that one). If JVM2 were to come out, and if it supported garbage collection, it’s likely that porting it will be easy enough for someone to handle the task of transitioning the JVM1 build to JVM2. Implementing a lisp is not a rare hobby, and IMO Clojure’s language design makes it a particularly tasty flavor of lisp.