refactor: Move example-nix to examples/nix/default.nix to keep flake.nix small

examples/nix/default.nix

@@ -0,0 +1,98 @@
+{ inputs
+, aws-sdk-cpp
+, bison
+, boehmgc
+, boost
+, brotli
+, busybox-sandbox-shell
+, bzip2
+, cmake
+, curl
+, doxygen
+, editline
+, flex
+, gtest
+, lib
+, libarchive
+, libblake3
+, libcpuid
+, libgit2
+, libseccomp
+, libsodium
+, lowdown
+, mkMesonPackage
+, nlohmann_json
+, openssl
+, perl
+, perlPackages
+, pkg-config
+, rapidcheck
+, readline
+, sqlite
+, toml11
+}:
+
+mkMesonPackage {
+  name = "example-nix";
+  src = inputs.nix;
+  target = "src/nix/nix";
+
+  nixNinjaExtraInputs = [
+    "src/libexpr/libnixexpr.so.p/meson-generated_.._parser-tab.cc.o:../src/libexpr/parser.y"
+    "src/libexpr/libnixexpr.so.p/meson-generated_.._lexer-tab.cc.o:../src/libexpr/parser.y"
+    "src/libexpr/libnixexpr.so.p/meson-generated_.._lexer-tab.cc.o:../src/libexpr/lexer.l"
+    "src/libexpr/libnixexpr.so.p/eval.cc.o:../src/libexpr/parser.y"
+    "src/libexpr/libnixexpr.so.p/lexer-helpers.cc.o:../src/libexpr/parser.y"
+  ];
+
+  nativeBuildInputs = [
+    aws-sdk-cpp
+    bison
+    boehmgc
+    boost
+    brotli
+    busybox-sandbox-shell
+    bzip2
+    cmake
+    curl
+    doxygen
+    editline
+    flex
+    libarchive
+    libblake3
+    libcpuid
+    libgit2
+    libseccomp
+    libsodium
+    lowdown
+    nlohmann_json
+    openssl
+    perl
+    pkg-config
+    readline
+    sqlite
+    toml11
+  ];
+
+  buildInputs = [
+    rapidcheck
+    gtest
+  ];
+
+  # dontAddPrefix = true;
+
+  mesonFlags = [
+    "--prefix=/build/tmp"
+    "--bindir=/build/tmp/bin"
+    "--mandir=/build/tmp/man"
+    (lib.mesonOption "perl:dbi_path" "${perlPackages.DBI}/${perl.libPrefix}")
+    (lib.mesonOption "perl:dbd_sqlite_path" "${perlPackages.DBDSQLite}/${perl.libPrefix}")
+  ];
+
+  env = {
+    # Needed for Meson to find Boost.
+    # https://github.com/NixOS/nixpkgs/issues/86131.
+    BOOST_INCLUDEDIR = "${lib.getDev boost}/include";
+    BOOST_LIBRARYDIR = "${lib.getLib boost}/lib";
+  };
+}

flake.nix

@@ -127,69 +127,8 @@
         target = "main";
       };
 
-      example-nix = mkMesonPackage {
-        name = "example-nix";
-        src = inputs.nix;
-        target = "src/nix/nix";
-
-        nixNinjaExtraInputs = [
-          "src/libexpr/libnixexpr.so.p/meson-generated_.._parser-tab.cc.o:../src/libexpr/parser.y"
-          "src/libexpr/libnixexpr.so.p/meson-generated_.._lexer-tab.cc.o:../src/libexpr/parser.y"
-          "src/libexpr/libnixexpr.so.p/meson-generated_.._lexer-tab.cc.o:../src/libexpr/lexer.l"
-          "src/libexpr/libnixexpr.so.p/eval.cc.o:../src/libexpr/parser.y"
-          "src/libexpr/libnixexpr.so.p/lexer-helpers.cc.o:../src/libexpr/parser.y"
-        ];
-
-        nativeBuildInputs = with pkgs; [
-          aws-sdk-cpp
-          bison
-          boehmgc
-          boost
-          brotli
-          busybox-sandbox-shell
-          bzip2
-          cmake
-          curl
-          doxygen
-          editline
-          flex
-          libarchive
-          libblake3
-          libcpuid
-          libgit2
-          libseccomp
-          libsodium
-          lowdown
-          nlohmann_json
-          openssl
-          perl
-          pkg-config
-          readline
-          sqlite
-          toml11
-        ];
-
-        buildInputs = with pkgs; [
-          rapidcheck
-          gtest
-        ];
-
-        # dontAddPrefix = true;
-
-        mesonFlags = with pkgs; [
-          "--prefix=/build/tmp"
-          "--bindir=/build/tmp/bin"
-          "--mandir=/build/tmp/man"
-          (lib.mesonOption "perl:dbi_path" "${perlPackages.DBI}/${perl.libPrefix}")
-          (lib.mesonOption "perl:dbd_sqlite_path" "${perlPackages.DBDSQLite}/${perl.libPrefix}")
-        ];
-
-        env = with pkgs; {
-          # Needed for Meson to find Boost.
-          # https://github.com/NixOS/nixpkgs/issues/86131.
-          BOOST_INCLUDEDIR = "${lib.getDev boost}/include";
-          BOOST_LIBRARYDIR = "${lib.getLib boost}/lib";
-        };
+      example-nix = pkgs.callPackage ./examples/nix {
+        inherit inputs mkMesonPackage;
       };
 
     in