36 lines
1.2 KiB
Nix
36 lines
1.2 KiB
Nix
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# `dhallPackageToNix` is a utility function to take a Nixpkgs Dhall package
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# (created with a function like `dhallPackages.buildDhallDirectoryPackage`)
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# and read it in as a Nix expression.
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#
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# This function is similar to `dhallToNix`, but takes a Nixpkgs Dhall package
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# as input instead of raw Dhall code.
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#
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# Note that this uses "import from derivation" (IFD), meaning that Nix will
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# perform a build during the evaluation phase if you use this
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# `dhallPackageToNix` utility. It is not possible to use `dhallPackageToNix`
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# in Nixpkgs, since the Nixpkgs Hydra doesn't allow IFD.
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{ stdenv, dhall-nix }:
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dhallPackage:
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let
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drv = stdenv.mkDerivation {
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name = "dhall-compiled-package.nix";
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buildCommand = ''
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# Dhall requires that the cache is writable, even if it is never written to.
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# We copy the cache from the input package to the current directory and
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# set the cache as writable.
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cp -r "${dhallPackage}/.cache" ./
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export XDG_CACHE_HOME=$PWD/.cache
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chmod -R +w ./.cache
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dhall-to-nix <<< "${dhallPackage}/binary.dhall" > $out
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'';
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nativeBuildInputs = [ dhall-nix ];
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};
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in
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import drv
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