[Nix-dev] Vastly improved R support

[Peter Simons]

Hi guys,

I just wanted to share some good news. Thanks to the heroic effort of @taku0 in
[1], we have now vastly improved support for R in Nixpkgs. We support almost
all of CRAN, and Nix can reliably install some 5816 packages:

  http://hydra.cryp.to/jobset/nixpkgs/r-packages

Furthermore, it's become easier to update the package set without losing manual
changes to the build expressions since now auto-generated code and manually
maintained code live in separate modules.

There is one issue that concerns me, though: apparently, some R modules require
a running X server for Tcl/Tk to build. We remedy this via xvfb-run(1) in
pkgs/development/r-modules/generic-builder.nix, but this feels really odd. Even
more so since xvfb-run has been reported to have trouble with more than one
instance running in parallel, so we added another flock(1) hack on top of the
xvfb-run hack.

Personally, I don't know much about this whole X11 business, but it's hard to
believe for me that the "solution" we've implemented right now is the best one
possible. Does anyone, by any chance, have an idea how to improve that
situation?

Best regards
Peter

[1] https://github.com/NixOS/nixpkgs/pull/5078