I am looking at the GitHub repo for the Malt library developed in the book https://github.com/themetaschemer/malt. It looks like they use Racket (Scheme) vectors to implement tensors. I experimented with loading Keras simple models into Racket several years ago: the built in math library matrix support was fast enough for my needs so the book software may be both pedagogical and useful for smaller problems.

EDIT: I have not tried the OpenBLAS Racket bindings here (https://github.com/soegaard/sci) but perhaps the low level tensor and tensor ops book code could be optimized,