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Diffstat (limited to 'pkgs/development/interpreters/dhall/build-dhall-package.nix')
-rw-r--r-- | pkgs/development/interpreters/dhall/build-dhall-package.nix | 83 |
1 files changed, 83 insertions, 0 deletions
diff --git a/pkgs/development/interpreters/dhall/build-dhall-package.nix b/pkgs/development/interpreters/dhall/build-dhall-package.nix new file mode 100644 index 000000000000..739dc9b3d52e --- /dev/null +++ b/pkgs/development/interpreters/dhall/build-dhall-package.nix @@ -0,0 +1,83 @@ +{ haskell, haskellPackages, lib, lndir, runCommand, writeText }: + +{ name + + # Expressions to add to the cache before interpreting the code +, dependencies ? [] + + # A Dhall expression + # + # Carefully note that the following expression must be devoid of uncached HTTP + # imports. This is because the expression will be evaluated using an + # interpreter with HTTP support disabled, so all HTTP imports have to be + # protected by an integrity check that can be satisfied via cached + # dependencies. + # + # You can add a dependency to the cache using the preceding `dependencies` + # option +, code + + # `buildDhallPackage` can include both a "source distribution" in + # `source.dhall` and a "binary distribution" in `binary.dhall`: + # + # * `source.dhall` is a dependency-free αβ-normalized Dhall expression + # + # * `binary.dhall` is an expression of the form: `missing sha256:${HASH}` + # + # This expression requires you to install the cache product located at + # `.cache/dhall/1220${HASH}` to successfully resolve + # + # By default, `buildDhallPackage` only includes "binary.dhall" to conserve + # space within the Nix store, but if you set the following `source` option to + # `true` then the package will also include `source.dhall`. +, source ? false +}: + +let + # `buildDhallPackage` requires version 1.25.0 or newer of the Haskell + # interpreter for Dhall. Given that the default version is 1.24.0 we choose + # the latest available version instead until the default is upgraded. + # + # HTTP support is disabled in order to force that HTTP dependencies are built + # using Nix instead of using Dhall's support for HTTP imports. + dhall = + haskell.lib.justStaticExecutables + (haskell.lib.appendConfigureFlag + haskellPackages.dhall_1_29_0 + "-f-with-http" + ); + + file = writeText "${name}.dhall" code; + + cache = ".cache"; + + cacheDhall = "${cache}/dhall"; + + sourceFile = "source.dhall"; + +in + runCommand name { inherit dependencies; } '' + set -eu + + mkdir -p ${cacheDhall} + + for dependency in $dependencies; do + ${lndir}/bin/lndir -silent $dependency/${cacheDhall} ${cacheDhall} + done + + export XDG_CACHE_HOME=$PWD/${cache} + + mkdir -p $out/${cacheDhall} + + ${dhall}/bin/dhall --alpha --file '${file}' > $out/${sourceFile} + + SHA_HASH=$(${dhall}/bin/dhall hash <<< $out/${sourceFile}) + + HASH_FILE="''${SHA_HASH/sha256:/1220}" + + ${dhall}/bin/dhall encode --file $out/${sourceFile} > $out/${cacheDhall}/$HASH_FILE + + echo "missing $SHA_HASH" > $out/binary.dhall + + ${lib.optionalString (!source) "rm $out/${sourceFile}"} + '' |