add dhall packages

default.nix

@@ -5,11 +5,23 @@ let
   callPackage = pkgs.lib.callPackageWith (pkgs // self);
   x = callPackage ./pkgs/x { };
   quickserv = callPackage sources.quickserv { };
+  dhall = callPackage sources.easy-dhall-nix { };
 
   self = {
+    # nix tools
+    dhallToNix = import ./dhallToNix.nix;
+
+    # other
     MoonPlus = callPackage ./pkgs/moonplus { };
     minica = callPackage ./pkgs/minica { };
 
+    # dhall
+    dhall = dhall.dhall-simple;
+    dhall-bash = dhall.dhall-bash-simple;
+    dhall-nix = dhall.dhall-nix-simple;
+    dhall-json = dhall.dhall-json-simple;
+    dhall-yaml = dhall.dhall-yaml-simple;
+
     # lojban
     johaus = callPackage ./pkgs/johaus { };
     jvozba = callPackage ./pkgs/jvozba { };
@@ -23,6 +35,6 @@ let
     mainsanow = x.mainsanow;
     prefix = x.prefix;
 
-    inherit x quickserv;
+    inherit quickserv x;
   };
 in self

dhallToNix.nix

@@ -0,0 +1,21 @@
+let
+  sources = import ./nix/sources.nix;
+  pkgs = import sources.nixpkgs { };
+  withPkg = pkgs.lib.callPackageWith pkgs;
+  dhall = withPkg sources.easy-dhall-nix { };
+
+in code:
+  let
+    file = builtins.toFile "dhall-expr" code;
+
+    drv = pkgs.stdenv.mkDerivation {
+      name = "dhall-expr-as-nix";
+
+      buildCommand = ''
+        dhall-to-nix <<< "${file}" > $out
+      '';
+
+      buildInputs = [ dhall.dhall-nix-simple ];
+    };
+  in
+    import "${drv}"

nix/sources.json

@@ -11,6 +11,18 @@
         "url": "https://github.com/pigpigyyy/MoonPlus/archive/d0583829535462a070e7ae90c6ea13f14244d060.tar.gz",
         "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
     },
+    "easy-dhall-nix": {
+        "branch": "master",
+        "description": "Derivations for easily downloading Dhall binaries and putting them to use.",
+        "homepage": "",
+        "owner": "justinwoo",
+        "repo": "easy-dhall-nix",
+        "rev": "735ad924fd829c9bbee0a167e0b2bbbf91e2cad5",
+        "sha256": "1r3sqs1cz0mcfwfvaq1d21vnppg5sqzqdl6w9krsw5ad5czkk190",
+        "type": "tarball",
+        "url": "https://github.com/justinwoo/easy-dhall-nix/archive/735ad924fd829c9bbee0a167e0b2bbbf91e2cad5.tar.gz",
+        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
+    },
     "niv": {
         "branch": "master",
         "description": "Easy dependency management for Nix projects",