[Nix-dev] Haskell packages don't show up in "nix-env -qa" (was: Confused about packages)

[Peter Simons]

Hi folks,

 >> Q 2. Why can't I find some packages that I would expect to find?
 >
 > I guess this would be because of haskellPackages missing recurseIntoAttrs.
 > I can't see it in there and no haskell packages are shown for me on master.

the lack of recurseIntoAttrs is intentional. We'd suffer a significant
performance loss if nix-env were to traverse the Haskell package set,
because 'haskellPackages' defines 8000+ entries! Right now, we have a
total of

  $ nix-env -qa | wc -l
  11353

entries in Nixpkgs. Haskell adds another

  $ nix-env -qa -A haskellPackages | wc -l
  8061

and then there's also R:

  $ nix-env -qa -A rPackages | wc -l
  6323

I would like those packages to be visible during nix-env -qa, but Nix is
just not fast enough to cope (unless you're running it on a modern
machine with a fast SSD).

If anyone has a suggestion how to deal with that situation, then I'd be
glad to hear it!

Best regards,
Peter