Source filtering

[roberth]

Changes to unrelated files cause rebuilds, especially when the package is at the root of the repo, where non-package files have no other place to go.

Some solutions:
a. parse the cabal file in Nix: no experimental features required, but somewhat hard to get right, not future proof
b. or use ca-derivations with buildFromSdist or buildFromCabalSdist (NixOS/nixpkgs#174176)

[srid]

This can also do this, right? https://github.com/numtide/nix-filter

One would have manually set up the filters, however.

[roberth]

Yeah, a basic solution is to make the src configurable for the package. (or packages #7 ) Users can then make use of any filtering library they like (lib, nix-filter, lib.sources combinators (a bit heavy as a flake though), ...).

[srid]

@roberth Is this still relevant?

[roberth]

While technically the automated filtering can still be improved, I don't think it's significant or important enough.
It's best to put a haskell package in its own directory anyway, in which case it would seem unlikely that you'd have any significant amount of redundant files in such a directory.
And if you do, the usual source filtering can be done by setting packages.<name>.root = someLib.someFunction ./<name>. Is that documented?

[ParetoOptimalDev]

It's best to put a haskell package in its own directory anyway,

Does this mean something like don't let Module.hs and .docker be in the same directory?

[srid]

https://community.flake.parts/haskell-flake/local#source-filtering