Andrew Kane, a developer who writes about Ruby on Rails, Postgres tools and machine learning gems for Ruby.
HN commenters link him for the list of Ruby machine learning gems and credit him with building dexter, an automatic Postgres indexer.
It's Python and the people using it - in theory pip + requirements.txt + virtualenv/conda should work, but here's over 1 million issues of people asking for requirements files or fixes to requirements files: https://github.com/search?q=requirements+file&type=issues
PS: For ML/DL enthusiasts, there is a small Ruby DL scene with some nice ported libraries done by the amazing @ankane - super infant right now, but if more folks use it, maybe we can bring Ruby to the DL mainstream? https://ankane.org/new-ml-gems
It looks like there was a little movement in the space not too far back:
https://ankane.org/new-ml-gems
But I don't know how often this is used in production. I've ended up training the models in python and then loading them in Ruby.
Andrew Kane wrote gems similar to popular ML libraries which are wrappers around C code: https://ankane.org/new-ml-gems
pytorch: https://github.com/ankane/torch.rb
Tensorflow: https://github.com/ankane/tensorflow-ruby
Andrew Kane built dexter, which is an automatic indexer for Postgres.
https://github.com/ankane/dexter
https://ankane.org/introducing-dexter
There are more than you might realize. Some good ones listed here:
https://ankane.org/new-ml-gems
https://ankane.org/more-ml-gems
This follow up was published in September, 2020: https://ankane.org/more-ml-gems