Not sure what they cover, but there are surely libraries available,
https://github.com/originrose/cortex
https://neanderthal.uncomplicate.org/
https://clojurecuda.uncomplicate.org/
https://clojurecl.uncomplicate.org/
https://github.com/uncomplicate/bayadera
https://devblogs.nvidia.com/grcuda-a-polyglot-language-bindi...
Also since Pytorch 1.4 there is initial support for Java, built on top of the new pure C++ API.
> - Is there a mature tensor/multidimensional array library in Clojure? Is there a Dataframe library?
Is there one in Java? If so, what?
And so on with his other items. It doesn't have to be exactly the same (offering him the benefit of the doubt), but it has to offer substantially the same functionality with substantially the same performance. So, you want to use Java libraries from Clojure? Go for it. Where are the things he needs?