nvim: [HACK] add command for non default formatters

modules/programs/nvim/default.nix

@@ -48,6 +48,7 @@ in
       withPython3 = true;
       extraLuaConfig = builtins.readFile ./init.lua;
       extraPackages = with pkgs; [
+        alejandra
         black
         isort
         nil

modules/programs/nvim/init.lua

@@ -211,6 +211,12 @@ require("formatter").setup({
     yaml = {
       require("formatter.filetypes.yaml").yamlfmt,
     },
+
+    -- HACK to use specific formatters only when specified
+    alejandra = {
+      require("formatter.filetypes.nix").alejandra,
+    },
+
     -- Use the special "*" filetype for defining formatter configurations on
     -- any filetype
     ["*"] = {
@@ -220,6 +226,21 @@ require("formatter").setup({
     },
   },
 })
+vim.api.nvim_create_user_command("Fmt", function(opts)
+  local params = vim.split(opts.args, "%s+", { trimempty = true })
+  local filetype = vim.bo.filetype
+  vim.cmd("set filetype=" .. params[1]) -- fake filetype
+  vim.cmd(":Format")
+  vim.cmd("set filetype=" .. filetype) -- restore original filetype
+end, {
+  nargs = 1,
+  complete = function()
+    local languages = {
+      nix = { "alejandra" },
+    }
+    return languages[vim.bo.filetype] or {}
+  end,
+})
 wk.register({
   ["="] = { "<cmd>Format<cr>", "format (formatter)" },
 }, { noremap = true, silent = true })