Julia

tl;dr Use the julia_16-bin package.

There are a number of other julia* attributes but most of them are broken. Work is ongoing to add macOS support (https://github.com/NixOS/nixpkgs/issues/123394).

Explanation:

-stable packages are for Julia LTS versions, which are very old at this point. I believe 1.0-ish. You probably want something more recent.
-bin packages are not built from source directly, but are instead built off of the official binaries released by Julia. Building Julia from source has proven to be quite a nightmare, so the -bin packages take the easy route. From the end-user perspective, -bin packages should be indistinguishable from source built ones.