diff options
Diffstat (limited to 'pkgs/development/interpreters/dhall')
-rw-r--r-- | pkgs/development/interpreters/dhall/build-dhall-url.nix | 96 |
1 files changed, 96 insertions, 0 deletions
diff --git a/pkgs/development/interpreters/dhall/build-dhall-url.nix b/pkgs/development/interpreters/dhall/build-dhall-url.nix new file mode 100644 index 0000000000000..766fe3c1c2e3f --- /dev/null +++ b/pkgs/development/interpreters/dhall/build-dhall-url.nix @@ -0,0 +1,96 @@ +{ cacert, dhall, dhall-docs, haskell, lib, runCommand }: + +# `buildDhallUrl` is similar to `buildDhallDirectoryPackage` or +# `buildDhallGitHubPackage`, but instead builds a Nixpkgs Dhall package +# based on a hashed URL. This will generally be a URL that has an integrity +# check in a Dhall file. +# +# Similar to `buildDhallDirectoryPackage` and `buildDhallGitHubPackage`, the output +# of this function is a derivation that has a `binary.dhall` file, along with +# a `.cache/` directory with the actual contents of the Dhall file from the +# suppiled URL. +# +# This function is primarily used by `dhall-to-nixpkgs directory --fixed-output-derivations`. + +{ # URL of the input Dhall file. + # example: "https://raw.githubusercontent.com/cdepillabout/example-dhall-repo/c1b0d0327146648dcf8de997b2aa32758f2ed735/example1.dhall" + url + + # Nix hash of the input Dhall file. + # example: "sha256-ZTSiQUXpPbPfPvS8OeK6dDQE6j6NbP27ho1cg9YfENI=" +, hash + + # Dhall hash of the input Dhall file. + # example: "sha256:6534a24145e93db3df3ef4bc39e2ba743404ea3e8d6cfdbb868d5c83d61f10d2" +, dhallHash + + # Name for this derivation. +, name ? (baseNameOf url + "-cache") + + # `buildDhallUrl` 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, `buildDhallUrl` 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 + # HTTP support is disabled in order to force that HTTP dependencies are built + # using Nix instead of using Dhall's support for HTTP imports. + dhallNoHTTP = haskell.lib.appendConfigureFlag dhall "-f-with-http"; + + # This uses Dhall's remote importing capabilities for downloading a Dhall file. + # The output Dhall file has all imports resolved, and then is + # alpha-normalized and binary-encoded. + downloadedEncodedFile = + runCommand + (baseNameOf url) + { + outputHashAlgo = null; + outputHash = hash; + name = baseNameOf url; + nativeBuildInputs = [ cacert ]; + } + '' + echo "${url} ${dhallHash}" > in-dhall-file + ${dhall}/bin/dhall --alpha --plain --file in-dhall-file | ${dhallNoHTTP}/bin/dhall encode > $out + ''; + + cache = ".cache"; + + data = ".local/share"; + + cacheDhall = "${cache}/dhall"; + + dataDhall = "${data}/dhall"; + + sourceFile = "source.dhall"; + +in + runCommand name { } ('' + set -eu + + mkdir -p ${cacheDhall} $out/${cacheDhall} + + export XDG_CACHE_HOME=$PWD/${cache} + + SHA_HASH="${dhallHash}" + + HASH_FILE="''${SHA_HASH/sha256:/1220}" + + cp ${downloadedEncodedFile} $out/${cacheDhall}/$HASH_FILE + + echo "missing $SHA_HASH" > $out/binary.dhall + '' + + lib.optionalString source '' + ${dhallNoHTTP}/bin/dhall decode --file ${downloadedEncodedFile} > $out/${sourceFile} + '') |