> They can interoperate through OS-level abstractions like pipes and via C APIs on at the process level.
And you can't do this in OSX or iOS?
> The average Unix desktop or server is probably running code written in 5-10 languages, more or less transparently to the user
The average iPhone is probably running code written in just as many (if not more) languages - C, C++, Obj-C, Swift, and Javascript are a given before you even look at third party stuff. And, modulo sandboxing, you can do all the Unix stuff too.
I actually don't have any opinion on how many languages have 'first-class' support on iOS. My understanding is that it's somewhat more complicated to create natural-seeming bindings from other languages to Objective-C APIs than it would be for C APIs, and that there are restrictions in the type of applications you can distribute using other languages (no downloadable code outside the App Store). Whether that makes those languages not 'first-class' on the platform is up to interpretation.
But the person I was responding to was specifically asking if any platform had first-class support for more than 1-2 languages. I don't know how to determine 'first-class' as a matter of principle, but I assumed that the multiple decades of polyglot software development on Unix environments would count. (OS X would count there, by the way.)
And you can't do this in OSX or iOS?
> The average Unix desktop or server is probably running code written in 5-10 languages, more or less transparently to the user
The average iPhone is probably running code written in just as many (if not more) languages - C, C++, Obj-C, Swift, and Javascript are a given before you even look at third party stuff. And, modulo sandboxing, you can do all the Unix stuff too.