Tweag + Nix dev update #11

Not a very long update for today, because a large part of the team is insanely busy interviewing the always growing stream of candidates for the summer of Nix (which is awesome, keep coming!).

Content-addressed Nix

Content-addressed Nix has now reached a beta quality level, and we’re eager for some testing and feedback!

To prepare for this, @regnat did a bunch of work on the broader Nix ecosystem:

  • With the latest nixos-unstable versions, it’s now possible to build everything as content-addressed, just by setting the right config field (#120316 and #120993)
  • The nixUnstable version has also been updated to bring the latest fixes to the feature to make the testing easier (#121263)
  • The hydra PR got a number of fixes. Thanks to @edolstra it is now properly deployed at Hydra - Jobset ca-test:nixpkgs (testing a subset of a content-addressed nixpkgs), with an associated binary cache at

In addition, this “release” process led to finding a few extra bugs, in particular #4764 (probably wontfix), #4766 (with a fix at #4767) and #4768 (fix coming soon).


@yannham has been preparing a talk for the coming LambdaJam conference. If you’re lucky enough to have a ticket, don’t miss his presentation!


@adisbladis Added a toplevel Makefile and @mmesch rewrote part of the README to make it easier to get started on the project.


And that’s all folks!