temp

source/generic-flake/main.adoc

@@ -16,34 +16,18 @@ writing your own flakes. I'll explain the example in some detail.
 
   inputs = {
     [.highlight01]#nixpkgs#.url = "github:NixOS/nixpkgs";
-    [.highlight02]#flake-utils#.url = "github:numtide/flake-utils";
     [.highlight03]#..._other dependencies_...# ❶
   };
 
-  outputs = { self, [.highlight01]#nixpkgs#, [.highlight02]#flake-utils#, [.highlight03]#..._other dependencies_...# ❷ }:
+  outputs = { self, [.highlight01]#nixpkgs#, [.highlight03]#..._other dependencies_...# ❷ }: {
-    flake-utils.lib.eachDefaultSystem (system: ❸
-      let
-        pkgs = import nixpkgs { inherit system; };
-        python = pkgs.python3;
-      in
-      {
-        devShells = rec {
-          default = pkgs.mkShell {
-            packages = [ #_packages needed for development shell_#; ❹ ];
-          };
-        };
 
-        packages = rec {
+    devShells = #_shell definitions_#; ❸
-          [.highlight04]#myPackageName# = #_package definition_#; ❺
-          default = [.highlight04]#myPackageName#;
-        };
 
-        apps = rec {
+    packages = #_package definitions_#; ❹
-          [.highlight04]#myPackageName# = flake-utils.lib.mkApp { drv = self.packages.${system}.[.highlight04]#myPackageName#; };
+
-          default = [.highlight04]#myPackageName#; ❻
+    apps = #_app definitions_#; ❺
-        };
+
-      }
+  };
-    );
 }
 ----
 
@@ -52,54 +36,84 @@ this part of the flake should be familiar. Remember also that any
 dependencies in the input section should also be listed at the beginning
 of the outputs section `❷`.
 
-Now it's time to look at the content of the output section. If we want
+The `devShells` attribute `❸` specifies the environment that should be
-the package to be available for multiple systems (e.g.,
+available when doing development on the package.
-"`x86_64-linux`", "`aarch64-linux`", "`x86_64-darwin`", and
+This includes any tools
-"`aarch64-darwin`"), we need to define the output for each of those
+(e.g., compilers and other language-specific build tools and packages).
-systems. Often the definitions are identical, apart from the name of the
+If you don't need a special development environment, you can omit this section.
-system. The eachDefaultSystem function `❸` provided by flake-utils allows
-us to write a single definition using a variable for the system name.
-The function then iterates over all default systems to generate the
-outputs for each one.
 
-The `devShells` variable specifies the environment that should be
+The `packages` attribute `❹` defines the packages that this flake provides.
-available when doing development on the package. If you don't need a
+The definition depends on the programming languages your
-special development environment, you can omit this section. At `❹` you
+software is written in, the build system you use, and more.
-would list any tools (e.g., compilers and language-specific build tools)
+There are Nix functions and tools that can simplify much of this, and new,
-you want to have available in a development shell. If the compiler needs
+easier-to-use ones are released regularly.
-access to language-specific packages, there are Nix functions to assist
+These functions are very language-specific, and not always well-documented.
-with that. These functions are very language-specific, and not always
+We will see examples for some languages later in the tutorial.
-well-documented. We will see examples for some languages later in the
+In general, I recommend that you do a web search for
-tutorial. In general, I recommend that you do a web search for
 "nix _language-name_", and try to find resources that were written or updated
 recently.
 
-The `packages` variable defines the packages that this flake provides.
+The `apps` attribute `❺` identifies any applications provided by the flake.
-The package definition `❺` depends on the programming languages your
+In particular, it identifies the default executable that `nix run`
-software is written in, the build system you use, and more. There are
-Nix functions and tools that can simplify much of this, and new,
-easier-to-use ones are released regularly. Again, I recommend that you
-do a web search for "nix _language-name_", and try to find resources that
-were written or updated recently.
-
-The `apps` variable identifies any applications provided by the flake.
-In particular, it identifies the default executable ❻ that `nix run`
 will run if you don't specify an app.
 
+
+If we want the development shell, packages, and apps
+to be available for multiple systems
+(e.g., `x86_64-linux`, `aarch64-linux`, `x86_64-darwin`, and
+`aarch64-darwin`),
+we need to provide a definition for each of those systems.
+The result _could_ be an outputs section like the one shown below.
+
+[source,subs=quotes]
+----
+  outputs = { self, [.highlight01]#nixpkgs#, [.highlight03]#..._other dependencies_...# ❷ }: {
+
+    devShells.x86_64-linux.default = ...;
+    devShells.aarch64-linux.default = ...;
+    . . .
+
+    packages.x86_64-linux.my-app = ...;
+    packages.aarch64-linux.my-app = ...;
+    . . .
+
+    apps.x86_64-linux.my-app = ...;
+    apps.aarch64-linux.my-app = ...;
+    . . .
+
+    apps.x86_64-linux.default = ...;
+    apps.aarch64-linux.default = ...;
+    . . .
+  };
+----
+
+You won't see definitions like that in most flakes.
+Typically the definitions for each shell, package or app
+would be identical, apart from a reference to the system name.
+There are techniques and tools that allow you to write a single definition
+and use it to automatically generate the definitions for multiple architectures.
+We will see some examples of this later in the tutorial.
+
 Below is a list of some functions that are commonly used in
-this section.
+the output section.
 
 General-purpose::
-  The standard environment provides
+- https://noogle.dev/f/pkgs/stdenv/mkDerivation[`mkDerivation`]
-  https://noogle.dev/f/pkgs/stdenv/mkDerivation[`mkDerivation`],
+  is especially useful for the typical
-  which is especially useful for the typical
   `./configure; make; make install` scenario.
   It's customisable.
+- https://nixos.org/manual/nixpkgs/unstable/#sec-pkgs-mkShell[`mkShell`]
+  simplifies writing a development shell definition.
+- https://nixos.org/manual/nixpkgs/unstable/#trivial-builder-writeShellApplication[`writeShellApplication`]
+  creates an executable shell script which also defines the appropriate environment.
 Python::
-  `buildPythonApplication`, `buildPythonPackage`.
+- `buildPythonApplication`
+- `buildPythonPackage`.
 Haskell::
-  `mkDerivation` (Haskell version, which is a wrapper around the
+- `mkDerivation` (Haskell version, which is a wrapper around the
-  standard environment version), `developPackage`, `callCabal2Nix`.
+  standard environment version)
+- `developPackage`
+- `callCabal2Nix`.
 
 
 [NOTE]

source/nix-language/attribute-sets.adoc

@@ -109,3 +109,11 @@ Remove one or more keys and associated values from a set.
 nix-repl> builtins.removeAttrs animal [ "age" "species" ]
 { name = "Professor Paws"; }
 ....
+
+Display an attribute set, including nested sets.
+
+[source]
+....
+nix-repl> builtins.toJSON animal
+"{\"age\":10,\"name\":{\"first\":\"Professor\",\"last\":\"Paws\"},\"species\":\"cat\"}"
+....

source/recipes/devshell/nix-non-flake/tempwork/flake.lock

@@ -0,0 +1,77 @@
+{
+  "nodes": {
+    "flake-utils": {
+      "inputs": {
+        "systems": "systems"
+      },
+      "locked": {
+        "lastModified": 1731533236,
+        "narHash": "sha256-l0KFg5HjrsfsO/JpG+r7fRrqm12kzFHyUHqHCVpMMbI=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "11707dc2f618dd54ca8739b309ec4fc024de578b",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "hello-nix": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1757705465,
+        "narHash": "sha256-sJCQ9+8Dy+QF9ISaupp42+mGbuXtFyqbX85tWzeNPOI=",
+        "ref": "refs/heads/main",
+        "rev": "56044f61231c996e4ab795de1da89e5f79db3f4f",
+        "revCount": 5,
+        "type": "git",
+        "url": "https://codeberg.org/mhwombat/hello-nix"
+      },
+      "original": {
+        "type": "git",
+        "url": "https://codeberg.org/mhwombat/hello-nix"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1760194782,
+        "narHash": "sha256-fJqK9vyL6Ur2HbtJX1xtBN499+18XLeshXPb/B+Udgw=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "f84bf9b679e4b8524ab2a90cf854a4f691739457",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "flake-utils": "flake-utils",
+        "hello-nix": "hello-nix",
+        "nixpkgs": "nixpkgs"
+      }
+    },
+    "systems": {
+      "locked": {
+        "lastModified": 1681028828,
+        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
+        "owner": "nix-systems",
+        "repo": "default",
+        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

source/recipes/devshell/nix-non-flake/tempwork/flake.nix

@@ -0,0 +1,27 @@
+{
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs";
+    flake-utils.url = "github:numtide/flake-utils";
+    hello-nix = {
+      url = "git+https://codeberg.org/mhwombat/hello-nix";
+      flake = false;
+    };
+  };
+
+  outputs = { self, nixpkgs, flake-utils, hello-nix }:
+    flake-utils.lib.eachDefaultSystem (system:
+      let
+        pkgs = import nixpkgs {
+          inherit system;
+        };
+        helloNix = import hello-nix { inherit pkgs; };
+      in
+      {
+        devShells = rec {
+          default = pkgs.mkShell {
+            packages = [ helloNix ];
+          };
+        };
+      }
+    );
+}