It is according to Khronos anyway, for those that aren't already deeply invested into HLSL.
Khronos has been quite vocal that there is no further development on GLSL, they see that as a community effort, they only provide SPIR-V.
This is how vendor specific tooling eventually wins out, they kind of got lucky AMD decided to offer Mantle as basis for Vulkan, LunarG is doing the SDK, now NVidia contributed slang, otherwise they would still be arguing about OpenGL vNext.
Khronos has been quite vocal that there is no further development on GLSL, they see that as a community effort, they only provide SPIR-V.
This is how vendor specific tooling eventually wins out, they kind of got lucky AMD decided to offer Mantle as basis for Vulkan, LunarG is doing the SDK, now NVidia contributed slang, otherwise they would still be arguing about OpenGL vNext.