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nixpkgs/pkgs/development/interpreters/dhall/build-dhall-package.nix
Gabriel Gonzalez 9f2dd99705 Upate buildDhallPackage to use default version of Dhall
Now that the default version is sufficiently new we don't need to
pin the Dhall version any longer in `buildDhallPackage`
2020-04-11 09:07:58 -07:00

75 lines
2.2 KiB
Nix

{ dhall, haskell, 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
# 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";
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}
${dhallNoHTTP}/bin/dhall --alpha --file '${file}' > $out/${sourceFile}
SHA_HASH=$(${dhallNoHTTP}/bin/dhall hash <<< $out/${sourceFile})
HASH_FILE="''${SHA_HASH/sha256:/1220}"
${dhallNoHTTP}/bin/dhall encode --file $out/${sourceFile} > $out/${cacheDhall}/$HASH_FILE
echo "missing $SHA_HASH" > $out/binary.dhall
${lib.optionalString (!source) "rm $out/${sourceFile}"}
''