nano: add nix syntax hightlight, nano module: provide default (#21912)

this is awesome! thanks.

nixos/modules/programs/nano.nix

@@ -1,4 +1,4 @@
-{ config, lib, ... }:
+{ config, lib, pkgs, ... }:
 
 let
   cfg = config.programs.nano;
@@ -20,16 +20,22 @@ in
         example = ''
           set nowrap
           set tabstospaces
-          set tabsize 4
+          set tabsize 2
         '';
       };
+      syntaxHighlight = lib.mkOption {
+        type = lib.types.bool;
+        default = true;
+        description = "Whether to enable syntax highlight for various languages.";
+      };
     };
   };
 
   ###### implementation
 
   config = lib.mkIf (cfg.nanorc != "") {
-    environment.etc."nanorc".text = cfg.nanorc;
+    environment.etc."nanorc".text = lib.concatStrings [ cfg.nanorc
+      (lib.optionalString cfg.syntaxHighlight ''include "${pkgs.nano}/share/nano/*.nanorc"'') ];
   };
 
 }

pkgs/applications/editors/nano/default.nix

@@ -1,4 +1,4 @@
-{ stdenv, fetchurl
+{ stdenv, fetchurl, fetchFromGitHub
 , ncurses
 , texinfo
 , gettext ? null
@@ -10,7 +10,14 @@ assert enableNls -> (gettext != null);
 
 with stdenv.lib;
 
-stdenv.mkDerivation rec {
+let
+  nixSyntaxHighlight = fetchFromGitHub {
+    owner = "seitz";
+    repo = "nanonix";
+    rev = "17e0de65e1cbba3d6baa82deaefa853b41f5c161";
+    sha256 = "1g51h65i31andfs2fbp1v3vih9405iknqn11fzywjxji00kjqv5s";
+  };
+in stdenv.mkDerivation rec {
   name = "nano-${version}";
   version = "2.7.3";
   src = fetchurl {
@@ -30,6 +37,10 @@ stdenv.mkDerivation rec {
     substituteInPlace src/text.c --replace "__time_t" "time_t"
   '';
 
+  postInstall = ''
+    cp ${nixSyntaxHighlight}/nix.nanorc $out/share/nano/
+  '';
+
   meta = {
     homepage = http://www.nano-editor.org/;
     description = "A small, user-friendly console text editor";