Given a path (which points to a directory and a list of paths which
are below that path, build a “sparse” version of that directory, so
that it only contains the listed paths (and their children):
$ nix-build -E 'with import ./. {}; nix.sparseTree ./. [
./default.nix
./nix/readTree
./nix/buildLisp
./third_party/nixpkgs
./third_party/overlays
]'
/nix/store/0ynj0gc613fs6mfp9snqcvdj5gfxbdzg-sparse-depot
$ lr -t 'type == d' result/
result/
result/nix
result/nix/buildLisp
result/nix/buildLisp/example
result/nix/readTree
result/nix/readTree/tests
[…]
result/third_party
result/third_party/nixpkgs
result/third_party/overlays
result/third_party/overlays/haskell
result/third_party/overlays/haskell/patches
result/third_party/overlays/patches
This is useful if a derivation depends on depot.path (e. g. if it wants
to import depot at runtime). Usually this means that on every depot
commit (or even worse, every change of .git on a local machine), this
derivation has to be rebuild. By using sparseTree you can instead depend
on a stripped down version of depot which only contains the bits you
actually depend on, avoiding unrelated rebuilds.
Change-Id: I127b108c8b177c657fb46786d0a6256516fd2c52
Reviewed-on: https://cl.tvl.fyi/c/depot/+/3503
Tested-by: BuildkiteCI
Reviewed-by: tazjin <mail@tazj.in>
