modules/performance: add performance.byteCompileLua option

* add `performance.byteCompileLua.enable` toggle to enable or disable
  all byte compiling features
* add `performance.byteCompileLua.initLua` toggle to enable or
  disable byte compiling of init.lua
* add `writeByteCompiledLua` helper for saving byte compiled lua source
  code to the nix store
* `nixvim-print-init` utility is always pointed to uncompiled init.lua
* add tests

lib/builders.nix

@@ -26,4 +26,26 @@
         --indent-width 4 \
         "$out"
     '';
+
+  /*
+    Write a byte compiled lua file to the nix store.
+
+    # Type
+
+    ```
+    writeByteCompiledLua :: String -> String -> Derivation
+    ```
+
+    # Arguments
+
+    - [name] The name of the derivation
+    - [text] The content of the lua file
+  */
+  writeByteCompiledLua =
+    name: text:
+    pkgs.runCommandLocal name { inherit text; } ''
+      echo -n "$text" > "$out"
+
+      ${lib.getExe' pkgs.luajit "luajit"} -bd -- "$out" "$out"
+    '';
 }

modules/performance.nix

@@ -4,6 +4,16 @@ let
 in
 {
   options.performance = {
+    byteCompileLua = {
+      enable = lib.mkEnableOption "byte compiling of lua files";
+      initLua = lib.mkOption {
+        description = "Whether to byte compile init.lua.";
+        type = types.bool;
+        default = true;
+        example = false;
+      };
+    };
+
     combinePlugins = {
       enable = lib.mkEnableOption "combinePlugins" // {
         description = ''

modules/top-level/output.nix

@@ -206,7 +206,17 @@ in
         config.content
       ];
 
-      init = helpers.writeLua "init.lua" customRC;
+      textInit = helpers.writeLua "init.lua" customRC;
+      byteCompiledInit = helpers.writeByteCompiledLua "init.lua" customRC;
+      init =
+        if
+          config.type == "lua"
+          && config.performance.byteCompileLua.enable
+          && config.performance.byteCompileLua.initLua
+        then
+          byteCompiledInit
+        else
+          textInit;
 
       extraWrapperArgs = builtins.concatStringsSep " " (
         (optional (
@@ -232,7 +242,7 @@ in
         name = "nixvim-print-init";
         runtimeInputs = [ pkgs.bat ];
         text = ''
-          bat --language=lua "${init}"
+          bat --language=lua "${textInit}"
         '';
       };
 

tests/test-sources/modules/performance/byte-compile-lua.nix

@@ -0,0 +1,139 @@
+{ pkgs, helpers, ... }:
+let
+  isByteCompiledFun = ''
+    local function is_byte_compiled(filename)
+      local f = assert(io.open(filename, "rb"))
+      local data = assert(f:read("*a"))
+      -- Assume that file is binary if it contains null bytes
+      for i = 1, #data do
+        if data:byte(i) == 0 then
+          return true
+        end
+      end
+      return false
+    end
+
+    local function test_rtp_file(name, is_compiled)
+      local file = assert(vim.api.nvim_get_runtime_file(name, false)[1], "file " .. name .. " not found in runtime")
+      if is_compiled then
+        assert(is_byte_compiled(file), name .. " is expected to be byte compiled, but it's not")
+      else
+        assert(not is_byte_compiled(file), name .. " is not expected to be byte compiled, but it is")
+      end
+    end
+  '';
+in
+{
+  default.module =
+    { config, ... }:
+    {
+      performance.byteCompileLua.enable = true;
+
+      extraFiles = {
+        "plugin/file_text.lua".text = "vim.opt.tabstop = 2";
+        "plugin/file_source.lua".source = helpers.writeLua "file_source.lua" "vim.opt.tabstop = 2";
+        "plugin/test.vim".text = "set tabstop=2";
+        "plugin/test.json".text = builtins.toJSON { a = 1; };
+      };
+
+      files = {
+        "plugin/file.lua" = {
+          opts.tabstop = 2;
+        };
+        "plugin/file.vim" = {
+          opts.tabstop = 2;
+        };
+      };
+
+      extraPlugins = [ pkgs.vimPlugins.nvim-lspconfig ];
+
+      extraConfigLua = ''
+        -- The test will search for this string in nixvim-print-init output: VALIDATING_STRING.
+        -- Since this is the comment, it won't appear in byte compiled file.
+      '';
+
+      # Using plugin for the test code to avoid infinite recursion
+      extraFiles."plugin/test.lua".text = ''
+        ${isByteCompiledFun}
+
+        -- vimrc is byte compiled
+        local init = vim.env.MYVIMRC or vim.fn.getscriptinfo({name = "init.lua"})[1].name
+        assert(is_byte_compiled(init), "MYVIMRC is expected to be byte compiled, but it's not")
+
+        -- nixvim-print-init prints text
+        local init_content = vim.fn.system("${config.printInitPackage}/bin/nixvim-print-init")
+        assert(init_content:find("VALIDATING_STRING"), "nixvim-print-init's output is byte compiled")
+
+        -- extraFiles
+        test_rtp_file("plugin/file_text.lua", false)
+        test_rtp_file("plugin/file_source.lua", false)
+        test_rtp_file("plugin/test.vim", false)
+        test_rtp_file("plugin/test.json", false)
+
+        -- files
+        test_rtp_file("plugin/file.lua", false)
+        test_rtp_file("plugin/file.vim", false)
+
+        -- Plugins and neovim runtime aren't byte compiled by default
+        test_rtp_file("lua/vim/lsp.lua", false)
+        test_rtp_file("lua/lspconfig.lua", false)
+      '';
+
+    };
+
+  disabled.module =
+    { config, ... }:
+    {
+      performance.byteCompileLua.enable = false;
+
+      extraFiles."plugin/test1.lua".text = "vim.opt.tabstop = 2";
+
+      files."plugin/test2.lua".opts.tabstop = 2;
+
+      extraPlugins = [ pkgs.vimPlugins.nvim-lspconfig ];
+
+      extraConfigLua = ''
+        -- The test will search for this string in nixvim-print-init output: VALIDATING_STRING.
+        -- Since this is the comment, it won't appear in byte compiled file.
+      '';
+
+      # Using plugin for the test code to avoid infinite recursion
+      extraFiles."plugin/test.lua".text = ''
+        ${isByteCompiledFun}
+
+        -- vimrc
+        local init = vim.env.MYVIMRC or vim.fn.getscriptinfo({name = "init.lua"})[1].name
+        assert(not is_byte_compiled(init), "MYVIMRC is not expected to be byte compiled, but it is")
+
+        -- nixvim-print-init prints text
+        local init_content = vim.fn.system("${config.printInitPackage}/bin/nixvim-print-init")
+        assert(init_content:find("VALIDATING_STRING"), "nixvim-print-init's output is byte compiled")
+
+        -- Nothing is byte compiled
+        -- extraFiles
+        test_rtp_file("plugin/test1.lua", false)
+        -- files
+        test_rtp_file("plugin/test2.lua", false)
+        -- Plugins
+        test_rtp_file("lua/lspconfig.lua", false)
+        -- Neovim runtime
+        test_rtp_file("lua/vim/lsp.lua", false)
+      '';
+
+    };
+
+  init-lua-disabled = {
+    performance.byteCompileLua = {
+      enable = true;
+      initLua = false;
+    };
+
+    extraConfigLuaPost = ''
+      ${isByteCompiledFun}
+
+      -- vimrc is not byte compiled
+      local init = vim.env.MYVIMRC or vim.fn.getscriptinfo({name = "init.lua"})[1].name
+      assert(not is_byte_compiled(init), "MYVIMRC is not expected to be byte compiled, but it is")
+    '';
+  };
+}