Stripe, Shopify and GitHub are still largely relying on Ruby as far as I know (and while there are reimplementations of some of their services in some languages, I don't think C++ or Java have been publicly mentioned often).
That said, I think one important asset of Elixir (in my view) is not the raw performance, but the overall "total cost of ownership" (including maintenance work, and software is a lot of maintenance).
Being able to simplify architectures is something that is nicely done with Elixir, actually.
If a part of an app needs to play a "proxy" role (like here https://github.com/etalab/transport-site/tree/master/apps/un...), then I just add a component to the app, and I can keep the incoming connections under hand, all while issuing external queries etc.
If there is a need to do some rich interactive dashboards, I can use LiveView.
If I need to demonstrate some simple stuff, I can use "Mix.install" to create one-off scripts.
If I need to do more data-science, I can tap into LiveBook, VegaLite etc.
All this with a small team or as a solo developer, is quite great, much more than raw performance, in my eyes.
That said, I think one important asset of Elixir (in my view) is not the raw performance, but the overall "total cost of ownership" (including maintenance work, and software is a lot of maintenance).
Being able to simplify architectures is something that is nicely done with Elixir, actually.
If a part of an app needs to play a "proxy" role (like here https://github.com/etalab/transport-site/tree/master/apps/un...), then I just add a component to the app, and I can keep the incoming connections under hand, all while issuing external queries etc.
If there is a need to do some rich interactive dashboards, I can use LiveView.
If I need to demonstrate some simple stuff, I can use "Mix.install" to create one-off scripts.
If I need to do more data-science, I can tap into LiveBook, VegaLite etc.
All this with a small team or as a solo developer, is quite great, much more than raw performance, in my eyes.