move devmode helper into flake

this cleans up the top-level directory and hopefully makes the setup
slightly more obvious

Co-authored-by: Alejandro Sanchez Medina <alejandrosanchzmedina@gmail.com>

README.md

@@ -7,7 +7,7 @@ Official documentation for getting things done with Nix.
 
 ## Contributing
 
-Run `./live` and open a browser at <http://localhost:5500>.
+Run `nix-shell --run devmode` and open a browser at <http://localhost:5500>.
 
 As you make changes your browser should auto-reload within a few seconds.
 

flake.nix

@@ -4,7 +4,7 @@
   inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-23.05";
   inputs.flake-utils.url = "github:numtide/flake-utils";
 
-  outputs = { self, nixpkgs, flake-utils}:
+  outputs = { self, nixpkgs, flake-utils }:
     flake-utils.lib.eachDefaultSystem (system:
       let
         pkgs = import nixpkgs {
@@ -15,7 +15,36 @@
             (import ./overlay.nix)
           ];
         };
-      in {
+        devmode =
+          let
+            pythonEnvironment = pkgs.python310.withPackages (ps: with ps; [
+              livereload
+            ]);
+            script = ''
+              from livereload import Server, shell
+
+              server = Server()
+
+              build_docs = shell("nix build")
+
+              print("Doing an initial build of the docs...")
+              build_docs()
+
+              server.watch("source/*", build_docs)
+              server.watch("source/**/*", build_docs)
+              server.watch("_templates/*.html", build_docs)
+              server.serve(root="result/")
+            '';
+          in
+          pkgs.writeShellApplication {
+            name = "devmode";
+            runtimeInputs = [ pythonEnvironment ];
+            text = ''
+              python ${pkgs.writeText "live.py" script}
+            '';
+          };
+      in
+      {
         packages.default = pkgs.stdenv.mkDerivation {
           name = "nix-dev";
           src = self;
@@ -39,17 +68,10 @@
         };
 
         devShells.default = pkgs.mkShell {
-          buildInputs = with pkgs.python310.pkgs; [
+          inputsFrom = [ self.packages.${system}.default ];
+          packages = with pkgs.python310.pkgs; [
             black
-            livereload
-            linkify-it-py
-            myst-parser
-            sphinx
-            sphinx-book-theme
-            sphinx-copybutton
-            sphinx-design
-            sphinx-notfound-page
-            sphinx-sitemap
+            devmode
           ];
         };
       }