Comment by pjmlp
5 years ago
Apple clearly states Swift is a systems programming language.
> Swift is a successor to both the C and Objective-C languages.
https://developer.apple.com/swift
> Swift is intended as a replacement for C-based languages (C, C++, and Objective-C).
There are systems languages and then there are systems languages. As the Golang team have pointed out, there's lots of systems programming going on outside of OS kernels. Neither of those links mention kernel development. Pervasive refcount updates (ARC) and a vtable-unfriendly dynamic dispatch mechanism inherited from Objective-C are fine for userspace, but most kernel code is very performance-sensitive.
Go team only changed their message due to the pitch forks they were getting from the UNIX/C crowd.
There are people that believe systems programming languages in an OS kernel is doable with some form of GC, and then there those that will never change their mind.
https://www.f-secure.com/en/consulting/foundry/usb-armory
https://blog.arduino.cc/2019/08/23/tinygo-on-arduino/
https://gvisor.dev/
https://github.com/mit-pdos/biscuit
https://github.com/ycoroneos/G.E.R.T
By the way, NeXTSTEP drivers were written in Objective-C, and the new userspace framework, DriverKit, is an homage to the NeXTSTEP driver API.
https://www.nextop.de/NeXTstep_3.3_Developer_Documentation/O...
I'm familiar with Biscuit and Midori. The Biscuit paper estimates a 10% performance hit in syscall-intensive benchmarks due to using Golang vs. C.
That being said, ARC may faire much better than a tracing GC, particularly in latency variance, throughput variance, and mean heap usage.
Though, I think we're best off moving off of hypervisors and onto 4th generation microkernels with isolation similar to AIX LPARs / Solaris Containers. After all, a hypervisor is essentially a microkernel that's forced to use hardware traps/faults plus hardware emulation for its syscall interface (plus upcalls for performance, which use a calling convention much closer to traditional syscalls). There are stability, security, and performance advantages to throwing out all of that hardware emulation code, moving everything to upcalls, and getting rid of the second (guest OS) kernel running between the application and the hardware. If you push most of the system functionality out of kernel space, then rewriting some of the less performance-critical components in a language with ARC or tracing GC starts to make more sense.
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