We believe that the D programming language can be a great candidate for writing kernel device drivers in a safe programming language. D is fully compatible with C and mechanically checks, during compilation, the user code for unsafe behavior. The language also boasts powerful compile-time features that make it possible to write highly specific, high performance code.
It also has a smooth learning curve and does not force language features onto the users, allowing them to gradually improve their code base, as they become more comfortable with the language.
We were able to integrate D in the kernel with minimal effort. It took us (a team of 4) 3 months to port the driver to D. We were able to use the existing kernel build system and weren't required to add extra support in the kernel for D.
Both D and Rust are a great step forward to writing safe software. Imhmo, having multiple options to choose from helps developers.