Better flake template

.envrc

@@ -1,12 +1,17 @@
 #!/usr/bin/env bash
 # ^ make editor happy
 
+#
+# Use https://direnv.net/ to automatically load the dev shell.
+#
+
 if ! has nix_direnv_version || ! nix_direnv_version 3.0.4; then
   source_url "https://raw.githubusercontent.com/nix-community/nix-direnv/3.0.4/direnvrc" "sha256-DzlYZ33mWF/Gs8DDeyjr8mnVmQGx7ASYqA5WlxwvBG4="
 fi  
 
 watch_file nix/**
 watch_file -- **/*.nix
 # Adding files to git includes them in a flake
-watch_file .git/index .git/HEAD
-use flake
+# But it is also a bit much reloading.
+# watch_file .git/index .git/HEAD
+use flake . --show-trace

crate2nix/flake-module.nix

@@ -7,7 +7,11 @@
     { pkgs
     , ...
     }@perSystem: {
-      devshells.default = {
+      # imports = [
+      #   inputs.pre-commit-hooks.flakeModule
+      # ];
+
+      config.devshells.default = {
         imports = [
           "${inputs.devshell}/extra/language/c.nix"
           "${inputs.devshell}/extra/language/rust.nix"
@@ -28,7 +32,7 @@
         };
       };
 
-      pre-commit = {
+      config.pre-commit = {
         settings.settings.rust.cargoManifestPath = "${self}/crate2nix/Cargo.toml";
 
         settings.hooks = {
@@ -38,6 +42,6 @@
         };
       };
 
-      packages.default = pkgs.callPackage ./default.nix { };
+      config.packages.default = pkgs.callPackage ./default.nix { };
     };
 }

docs/src/content/docs/00_guides/10_flake_template_new.md

@@ -22,7 +22,10 @@ If the directory is empty, it will also create a hello world stub.
 
 If you call this from an existing project, make sure to delete any superfluous
 files. The template expects top-level `Cargo.toml`/`Cargo.lock` files,
-otherwise you need to adjust `flake.nix` manually.
+and a single result binary, otherwise you need to adjust `flake.nix` manually.
+
+Continue to use `cargo`/`rust-analyzer` for a fast developer loop and use
+nix to verify your program hermetically with nix locally and in CI:
 
 ```bash title="Building project and running tests"
 nix build

docs/src/content/docs/index.mdx

@@ -7,8 +7,13 @@ import { Card, CardGrid } from '@astrojs/starlight/components';
 import { Icon } from '@astrojs/starlight/components';
 
 <Card title="What does crate2nix do?">
-`crate2nix` generates [nix](https://nixos.org/nix/) build files for [rust](https://www.rust-lang.org/) crates
-using [cargo](https://crates.io/) so that you can **build your rust project with nix**.
+`crate2nix` builds your [cargo](https://crates.io/)-based [rust](https://www.rust-lang.org/) project 
+crate-by-crate with [nix](https://nixos.org/nix/).
+
+You can 
+
+* save time by only rebuilding changed crates hermetically in CI, and
+* use `cargo`/`rust-analyzer` locally for a fast developing loop.
 </Card>
 
 **Dependency tree from cargo**: It uses [cargo_metadata](https://github.com/oli-obk/cargo_metadata) to obtain the

flake.nix

@@ -7,6 +7,7 @@
   nixConfig = {
     extra-trusted-public-keys = "eigenvalue.cachix.org-1:ykerQDDa55PGxU25CETy9wF6uVDpadGGXYrFNJA3TUs=";
     extra-substituters = "https://eigenvalue.cachix.org";
+    allow-import-from-derivation = true;
   };
 
   inputs = {
@@ -64,9 +65,12 @@
     ];
 
     flake = { lib, ... }: {
-      config.templates.default = {
-        path = ./template;
-        description = "An example of crate2nix";
+      config.templates = rec {
+        default = flake-binary;
+        flake-binary = {
+          path = ./templates/flake-binary;
+          description = "An example of crate2nix";
+        };
       };
 
       config.lib = {
@@ -99,7 +103,7 @@
       };
     };
 
-    perSystem = { config, self', inputs', pkgs, system, ... }: {
+    perSystem = { config, pkgs, ... }: {
       formatter = pkgs.nixpkgs-fmt;
       checks = config.packages;
     };

templates/flake-binary/.envrc

@@ -0,0 +1,17 @@
+#!/usr/bin/env bash
+# ^ make editor happy
+
+#
+# Use https://direnv.net/ to automatically load the dev shell.
+#
+
+if ! has nix_direnv_version || ! nix_direnv_version 3.0.4; then
+  source_url "https://raw.githubusercontent.com/nix-community/nix-direnv/3.0.4/direnvrc" "sha256-DzlYZ33mWF/Gs8DDeyjr8mnVmQGx7ASYqA5WlxwvBG4="
+fi  
+
+watch_file nix/**
+watch_file -- **/*.nix
+# Adding files to git includes them in a flake
+# But it is also a bit much reloading.
+# watch_file .git/index .git/HEAD
+use flake . --show-trace

templates/flake-binary/.gitignore

@@ -0,0 +1,22 @@
+target
+**/*.rs.bk
+.idea
+*.iml
+/result*
+*.log
+*~
+
+# cachix tmp file
+store-path-pre-build
+
+# Devenv
+.devenv*
+devenv.local.nix
+
+# direnv
+.direnv
+
+# pre-commit
+.pre-commit-config.yaml
+
+template/flake.lock