That’s the key statement in the error message. We haven’t yet built out all the operations to provide complete coverage of all GPU programming tasks on Apple Silicon GPUs yet, and support for print and debug_assert functions are still on our to-do list. We have a rough task list of items to be worked on in our announcement post for Apple Silicon GPU support, and I’ve been trying to keep that up to date as we fix or add new capabilities.
I can try to follow up once we do get print() support added on Apple Silicon GPUs. The calculation itself should work, but printing the threads may need to wait until that function is ready.