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|
{ pkgs, exactSource }:
let
# import the dhall file as nix expression via dhall-nix.
# Converts the normalized dhall expression to a nix file,
# puts it in the store and imports it.
# Types are erased, functions are converted to nix functions,
# unions values are nix functions that take a record of match
# functions for their alternatives.
importDhall = dhallType: file: importDhall2 {
root = builtins.dirOf file;
files = [];
main = builtins.baseNameOf file;
type = dhallType;
deps = [];
};
# TODO: document
importDhall2 = { root, files, main, deps, type }:
let
src =
exactSource
root
# exactSource wants nix paths, but I think relative paths
# as strings are more intuitive.
(let abs = path: toString root + "/" + path;
in ([ (abs main) ] ++ (map abs files)));
cache = ".cache";
cacheDhall = "${cache}/dhall";
convert = pkgs.runCommandLocal "dhall-to-nix" { inherit deps; } ''
mkdir -p ${cacheDhall}
for dep in $deps; do
${pkgs.xorg.lndir}/bin/lndir -silent $dep/${cacheDhall} ${cacheDhall}
done
export XDG_CACHE_HOME=$(pwd)/${cache}
# go into the source directory, so that the type can import files.
# TODO: This is a bit of a hack hrm.
cd "${src}"
printf '%s' ${pkgs.lib.escapeShellArg "${src}/${main} : ${type}"} \
| ${pkgs.dhall-nix}/bin/dhall-to-nix \
> $out
'';
in import convert;
# read dhall file in as JSON, then import as nix expression.
# The dhall file must not try to import from non-local URLs!
readDhallFileAsJson = dhallType: file:
let
convert = pkgs.runCommandLocal "dhall-to-json" {} ''
printf '%s' ${pkgs.lib.escapeShellArg "${file} : ${dhallType}"} \
| ${pkgs.dhall-json}/bin/dhall-to-json \
> $out
'';
in builtins.fromJSON (builtins.readFile convert);
in {
inherit
importDhall
importDhall2
readDhallFileAsJson
;
}
|
