Automatically regenerating Neovim spell files

.config/nvim/lua/config/autocmds.lua

@@ -0,0 +1,19 @@
+-- Ensure that the binary spl file is up-to-date with the source add file
+vim.api.nvim_create_autocmd("FocusGained", {
+  pattern = "*",
+  callback = function()
+    local config_path = vim.fn.stdpath("config") -- Get Neovim's config path
+    local add_file = config_path .. "/spell/en.utf-8.add"
+    local spl_file = config_path .. "/spell/en.utf-8.add.spl"
+
+    if vim.fn.filereadable(add_file) == 1 then
+      local add_mtime = vim.fn.getftime(add_file) -- Get modification time of .add file
+      local spl_mtime = vim.fn.getftime(spl_file) -- Get modification time of .add.spl file
+
+      -- Run mkspell! only if .add is newer than .add.spl or .add.spl doesn't exist
+      if add_mtime > spl_mtime or spl_mtime == -1 then
+        vim.cmd("silent! mkspell! " .. spl_file .. " " .. add_file)
+      end
+    end
+  end,
+})