Nixpkgs support for dhall-to-nixpkgs
#89237
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The motivation for this change is to enable a new Dhall command-line utility called `dhall-to-nixpkgs` which converts Dhall packages to buildable Nix packages. You can think of `dhall-to-nixpkgs` as the Dhall analog of `cabal2nix`. You can find the matching pull request for `dhall-to-nixpkgs` here: dhall-lang/dhall-haskell#1826 The two main changes required to support `dhall-to-nixpkgs` are: * Two new `buildDhall{Directory,GitHub}Package` utilities are added `dhall-to-nixpkgs` uses these in the generated output * `pkgs.dhallPackages` now selects a default version for each package using the `prefer` utility All other versions are still buildable via a `passthru` attribute
| buildDhallGitHubPackage = | ||
| callPackage ../development/interpreters/dhall/build-dhall-github-package.nix { }; |
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Does it make sense to specialize this to github in nixpkgs? The dhall builder can just assume that pkgs.fetchFromGitHub exists (it’s a stable interface of nixpkgs) and then put the result into src, which makes it easily extendable to other source locations.
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@Profpatsch: Yeah, it is possible to do that. Conceptually, that is what the lower-level buildDhallPackage utility already does, it just takes a src as input and buildDhall{GitHub,Directory}Package are just convenient wrappers around the buildDhallPackage.
The main reason I created these intermediate utilities was to keep the code generated by dhall-to-nixpkgs as small as possible, otherwise it would essentially be inlining the code that you see in build-dhall-github-package.nix into every generated GitHub derivation (including the mkOverridable and the removeAttrs boilerplate)
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@Profpatsch: Is there anything left to do here? |
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No, I’m sorry, this stagnated in my open tabs. Thanks for pinging again, I’ll merge. |
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I think we can try to build everything with ofborg: @GrahamcOfBorg build dhallPackages |
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@Profpatsch: Thank you! 🙂 |
The motivation for this change is to enable a new Dhall command-line
utility called
dhall-to-nixpkgswhich converts Dhall packages tobuildable Nix packages. You can think of
dhall-to-nixpkgsas theDhall analog of
cabal2nix.You can find the matching pull request for
dhall-to-nixpkgshere:dhall-lang/dhall-haskell#1826
The two main changes required to support
dhall-to-nixpkgsare:Two new
buildDhall{Directory,GitHub}Packageutilities are addeddhall-to-nixpkgsuses these in the generated outputpkgs.dhallPackagesnow selects a default version for each packageusing the
preferutilityAll other versions are still buildable via a
passthruattributeMotivation for this change
Things done
I also verified that all of
pkgs.dhallPackagesstill builds and I also verified that severalrepresentative Nix packages generated by
dhall-to-nixpkgssuccessfully build withthese changes.