From their GitHub repo description:
GitHub repo link is here: https://github.com/KhronosGroup/MoltenVKMoltenVK is an implementation of the high-performance, industry-standard Vulkan graphics and compute API, that runs on Apple's Metal graphics framework, bringing Vulkan compatibility to iOS and macOS.
Also this arsTechnica article: https://arstechnica.com/gadgets/2018/02 ... -to-apple/
If you're considering implementing Vulkan, this will probably help, instead of creating any Metal code just for macOS.
Update: On March 7, 2018 the new Vulkan 1.1 API Specification was released by KronosGroup.
Link to the Kronos Vulkan Registry: https://www.khronos.org/registry/vulkan/
There's also a Quick Reference PDF available at: https://www.khronos.org/registry/vulkan ... .1-web.pdf