r: added formatters

modules/plugins/languages/r.nix

@@ -18,6 +18,51 @@
     packages = with pkgs.rPackages; [languageserver];
   };
 
+  defaultFormat = "format_r";
+  formats = {
+    prettier = {
+      package = pkgs.nodePackages.prettier;
+      nullConfig = ''
+        local prettier = null_ls.builtins.formatting.prettier.with({
+          filetypes = { "r" },
+          extra_args = {
+            "--plugin", "prettier-plugin-r",
+            "--parser", "r"
+          }
+        })
+        table.insert(ls_sources, prettier)
+      '';
+    };
+
+    styler = {
+      package = pkgs.rWrapper.override {
+        packages = with pkgs.rPackages; [styler];
+      };
+      nullConfig = ''
+        table.insert(
+          ls_sources,
+          null_ls.builtins.formatting.styler.with({
+            command = "${cfg.format.package}/bin/R",
+          })
+        )
+      '';
+    };
+
+    format_r = {
+      package = pkgs.rWrapper.override {
+        packages = with pkgs.rPackages; [formatR];
+      };
+      nullConfig = ''
+        table.insert(
+          ls_sources,
+          null_ls.builtins.formatting.format_r.with({
+            command = "${cfg.format.package}/bin/R",
+          })
+        )
+      '';
+    };
+  };
+
   defaultServer = "r_language_server";
   servers = {
     r_language_server = {
@@ -62,6 +107,22 @@ in {
         default = servers.${cfg.lsp.server}.package;
       };
     };
+
+    format = {
+      enable = mkEnableOption "R formatting" // {default = config.vim.languages.enableFormat;};
+
+      type = mkOption {
+        description = "R formatter to use";
+        type = enum (attrNames formats);
+        default = defaultFormat;
+      };
+
+      package = mkOption {
+        description = "R formatter package";
+        type = package;
+        default = formats.${cfg.format.type}.package;
+      };
+    };
   };
 
   config = mkIf cfg.enable (mkMerge [
@@ -70,6 +131,11 @@ in {
       vim.treesitter.grammars = [cfg.treesitter.package];
     })
 
+    (mkIf cfg.format.enable {
+      vim.lsp.null-ls.enable = true;
+      vim.lsp.null-ls.sources.r-format = formats.${cfg.format.type}.nullConfig;
+    })
+
     (mkIf cfg.lsp.enable {
       vim.lsp.lspconfig.enable = true;
       vim.lsp.lspconfig.sources.r-lsp = servers.${cfg.lsp.server}.lspConfig;