diff options
| -rw-r--r-- | pkgs/profpatsch/default.nix | 6 | ||||
| -rw-r--r-- | pkgs/profpatsch/importDhall.nix | 62 |
2 files changed, 68 insertions, 0 deletions
diff --git a/pkgs/profpatsch/default.nix b/pkgs/profpatsch/default.nix index 08ce4dfc..aa72d1ce 100644 --- a/pkgs/profpatsch/default.nix +++ b/pkgs/profpatsch/default.nix @@ -184,4 +184,10 @@ in rec { buildDhallPackage = pkgs.callPackage ./dhall/build-dhall-package-improved.nix { inherit dhall; }; + inherit (import ./importDhall.nix { inherit pkgs dhall-nix dhall-json exactSource; }) + importDhall + importDhall2 + readDhallFileAsJson + ; + } diff --git a/pkgs/profpatsch/importDhall.nix b/pkgs/profpatsch/importDhall.nix new file mode 100644 index 00000000..96da75c9 --- /dev/null +++ b/pkgs/profpatsch/importDhall.nix @@ -0,0 +1,62 @@ +{ pkgs, dhall-nix, dhall-json, 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; + }; + + # 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} ${cacheDhall} + done + + export XDG_CACHE_HOME=./${cache} + printf '%s' ${pkgs.lib.escapeShellArg "${src}/${main} : ${type}"} \ + | ${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}"} \ + | ${dhall-json}/bin/dhall-to-json \ + > $out + ''; + in builtins.fromJSON (builtins.readFile convert); + +in { + inherit + importDhall + importDhall2 + readDhallFileAsJson + ; +} |