Move hydra.nix to default.nix

So it's easier to use as a classic (non-flake) Nix expression.

default.nix

@@ -1,2 +1,37 @@
-{ pkgs ? import <nixpkgs> {} }:
-pkgs.callPackage ./hydra.nix {}
+{ stdenv
+, lib
+, nixFlakes
+, meson
+, cmake
+, ninja
+, pkg-config
+, boost
+, nlohmann_json
+, srcDir ? null
+}:
+
+let
+  filterMesonBuild = dir: builtins.filterSource
+    (path: type: type != "directory" || baseNameOf path != "build") dir;
+in
+stdenv.mkDerivation rec {
+  pname = "nix-eval-jobs";
+  version = "0.0.1";
+  src = if srcDir == null then filterMesonBuild ./. else srcDir;
+  buildInputs = [
+    nlohmann_json nixFlakes boost
+  ];
+  nativeBuildInputs = [
+    meson pkg-config ninja
+    # nlohmann_json can be only discovered via cmake files
+    cmake
+  ];
+
+  meta = {
+    description = "Hydra's builtin hydra-eval-jobs as a standalone";
+    homepage = "https://github.com/nix-community/nix-eval-jobs";
+    license = lib.licenses.gpl3;
+    maintainers = with lib.maintainers; [ adisbladis mic92 ];
+    platforms = lib.platforms.unix;
+  };
+}

flake.nix

@@ -10,7 +10,7 @@
         pkgs = nixpkgs.legacyPackages.${system};
       in
       rec {
-        packages.nix-eval-jobs = pkgs.callPackage ./hydra.nix {
+        packages.nix-eval-jobs = pkgs.callPackage ./default.nix {
           srcDir = self;
         };
 

hydra.nix

@@ -1,36 +0,0 @@
-{ stdenv
-, lib
-, nixFlakes
-, meson
-, cmake
-, ninja
-, pkg-config
-, boost
-, nlohmann_json
-, srcDir ? null
-}:
-
-let
-  filterMesonBuild = dir: builtins.filterSource
-    (path: type: type != "directory" || baseNameOf path != "build") dir;
-in
-stdenv.mkDerivation rec {
-  pname = "nix-eval-jobs";
-  version = "0.0.1";
-  src = if srcDir == null then filterMesonBuild ./. else srcDir;
-  buildInputs = [
-    nlohmann_json nixFlakes boost
-  ];
-  nativeBuildInputs = [
-    meson pkg-config ninja
-    # nlohmann_json can be only discovered via cmake files
-    cmake
-  ];
-  meta = with lib; {
-    description = "Hydra's builtin hydra-eval-jobs as a standalone";
-    homepage = "https://github.com/nix-community/nix-eval-jobs";
-    license = licenses.gpl3;
-    maintainers = with maintainers; [ mic92 ];
-    platforms = platforms.unix;
-  };
-}