Tell that to your cell phone tower… its probably running plan9 so im some respects it is much less dead than Haiku and certainly more advanced design wise than POSIX. (Alcatel-Lucent stuff is all plan9 based).
Also MPI … seriously that is not even well integrated into the language or OS. The whole point on plan9 is that a resource is a resource even the CPU, if you are going to do something like this make it elegant… not some hack like anything added onto Unix as an extension.
One of the biggest problems right now for Haiku is there is no first class IDE… application developers need code completion, visual RAD tools etc, integrated debugging etc… it’s a long list but Haiku doesn’t have that so the barrier to entry for creating applications is pretty High (Higher even than it was for BeOS as it had CodeWarrior).
Whatever, most of the features Plan9 added in a lightweight manner have been hacked onto POSIX poorly, and inelegantly I might add. Also, if you wish to be disrespectful that is on you.
You are correct that Plan9 proper is largely historical, but it does still see development activity on it’s original codebase unlike BeOS… but as they say those that don’t know their history are doomed to repeat it.
POSIX is nice for a few base utilities and the toolchain… but frankly it is just holding everything else back and if you run across anyone actually looking at it … it becomes clear that it is largely a mess. So, yes a baseline of POSIX compatibility may be good just as Haiku has… but it isn’t a good platform to build on if you adhere to the original ideals of BeOS.
There seem to be some confusion about what POSIX is. It is a common agreement on the very minimal set of things any OS should implement anyway, and a common way to do it. That’s it. It does not define a complete OS interface for the modern world. Any OS which would try to be “strict POSIX and nothing more” would be missing several important parts to be really useful.
The main distinction is how extensions and things going outside POSIX are handled. Either, like Linux or *BSD, you try to evolve things while keeping the same spirit and adding stuff that blends in with POSIX. Or, more like Haiku or macOS, you have the POSIX API on one side, and another completely independant API next to it (even implemented in a different language - C++ in our case, Objective-C in macOS).
So, POSIX is a good platform to build on. But it’s just that, and you need to build something on it.
As to the confusion not in the least… POSIX is a flawed platform that is good enough. I don’t think many will contest that. The flaws are certainly the reason research went on and came up with alternatives… but they never caught on because muscle memory etc… had already set in with POSIX.
If you go an use plan9 it is definitly wierd… but some aspects of it are quite good (and some are extremely bad). For example the UI is very neat in how it is designed but what they actually made it into sucks and is quite stuck in the 80’s as it has little discoverability and sensible defaults… something Haiku is pretty good at in most cases.
Even though haiku is pretty different from Windows it isn’t difficult to adapt to.