There are a number of these, but most of the big ones are supported (e.g. emacs, vim, python and most common pypi packages, ghc and most haskell packages, ssh,

There are a number of these, but most of the big ones are supported (e.g. emacs, vim, python and most common pypi packages, ghc and most haskell packages, ssh, git, ssl, blah blah blah). The main challenge with supporting OSX is that the closed-source nature and/or proprietary license of a lot of the low-level system libraries, especially for graphical applications, doesn't play very well with nix, which does best with HTTP URLs from which (preferably) source code and/or (failing that) prebuilt binaries can be fetched, the contents of which are deterministic. That said, there are tens of thousands of packages that build on OSX, certainly many more than enough to be a very useful platform for package management, especially when coupled with all of the advantages that nix brings. The downsides are a higher learning curve and occasional missing and/or broken packages.