Build pub packages with Nix.

See the examples/ directory for usage.

Enter a Nix shell and the work as normal.

$ nix-shell
[nix-shell:~/pub2nix/examples/simple]$ pub run build_runner build

$ nix-shell
[nix-shell:~/pub2nix/examples/simple]$ pub2nix-lock
unpacking...
...
[nix-shell:~/pub2nix/examples/simple]$ exit

$ nix-build

We aim to build pub packages with Nix using only information found in pubspec.lock. However, pubspec.lock doesn't yet contain sha256 checksums, and Nix needs those in order to build each package.

As a stop-gap, we require users to generate a pub2nix.lock file which is a copy of pubspec.lock with an additional sha256 field for each package. We don't patch pubspec.lock directly since convenient YAML tooling changes the format in ways which Dart tooling complains about, e.g. failing to parse the Dart SDK version, as well as producing noisy diffs.

We then produce a .pub-cache directory using pub packages from the nix store, and call pub get --offline.