18:01 <emmanuel_erc> Hello there. I'm interested in learning about the nix tooling that is available for Haskell projects with haskell.nix (somewhat obviously, I suppose). Anyway, I haven't quite gotten a feel for whether it possible to do one thing in particular. Currently (according to my understanding), cabal2nix does something I don't quite like. When I use cabal or stack to build a project, only the files (and files that depend upon them) t

18:01 <emmanuel_erc> recently changed will only ever be compiled. However, when using cabal2nix, this doesn't happen at all. Does haskell.nix address this issue (if we're going to call it that)?

18:08 <michaelpj1> emmanuel_erc: let me check if I've understood: you don't like the fact that the Nix builds of Haskell packages are all-or-nothing, rather than incremental? Sadly, we can't easily avoid this problem to *some* degree, since the unit of caching in Nix is the derivation, and typically we have fairly large derivations. To get caching as good as cabal, we'd have to do one derivation per file. The nIxpkgs Haskell

18:08 <michaelpj1> infrastructure is one derivation per package; haskell.nix is slightly better with one derivation per component

18:08 <michaelpj1> but still, for day-to-day development, I would not recommend running `nix-build` in a loop, but rather using `shellFor` to get a shell with the right dependencies, and then using `cabal` or whatever inside that

18:08 <michaelpj1> that works totally fine, and then you get your normal cabal recompilation behaviuor

18:10 <emmanuel_erc> michaelpj1: Thank you for your answer.

18:12 <emmanuel_erc> Well, I was hoping there was a way to speed things up. However, being able to build a derivation per component is still something that I quite like.