Has there been a proposal? What's the current recommendation on the type to use for implementing a ByteBuffer analog if importing SWIFT-NIO isn't possible?
FWIW, I've really enjoyed poking around swift-nio (shout out to void CNIOLinux_i_do_nothing_just_working_around_a_darwin_toolchain_bug2(void) {} and HappyEyeBalls.swift) to get some ideas for putzing around with serial ports.
Sure would be wonderful to be able to have ByteBuffer, CircleBuffer and MarkedCircularBuffer around for some other projects I can think of, too... 
EDITED: Related conversation