Update nix-std to get toTOML that omits nulls (#234)

* update nix-std, add some comments

* format

Author: JonathanLorimer

flake.lock

@@ -31,6 +31,8 @@
         ./modules/apps.nix
         # Sets the overlays.default flake output
         ./modules/overlay.nix
+        # Sets the flake.nixosModules flake output
+        ./modules/nixosModules.nix
       ];
     };
 

flake.nix

@@ -140,9 +140,18 @@ nix-std: {
       }
       // buildGoModuleArgs);
 in {
+  # A helper for building rust cosmwasm smart contracts. Does some best practices like using binaryren wasm-opt
+  # to optimize the bytecode, and runs cosmwasm-check to validate.
   inherit buildCosmwasmContract;
+
+  # A wrapper around [buildGoModule](https://github.com/NixOS/nixpkgs/blob/master/pkgs/build-support/go/module.nix)
+  # that is specialized to packaging cosmos-sdk based go projects
+  #
+  # for more information see: https://github.com/NixOS/nixpkgs/blob/master/doc/languages-frameworks/go.section.md
   mkCosmosGoApp = buildApp;
 
+  # A helper function for patching cosmos-sdk binaries that use wasmd, so that the binary artifact references
+  # a nix store path, and not a local relative path
   wasmdPreFixupPhase = libwasmvm: binName:
     if pkgs.stdenv.hostPlatform.isLinux
     then ''
@@ -156,6 +165,8 @@ in {
     ''
     else null;
 
+  # A helper that produces an executable for generating a gomod2nix.toml file (which
+  # captures a go module's dependencies and their hash in a toml file)
   mkGenerator = name: srcDir:
     pkgs.writeShellApplication {
       inherit name;
@@ -168,6 +179,7 @@ in {
         gomod2nix --outdir "$CURDIR"
       '';
     };
+
   # `hermesModuleConfigToml { modules }).config.hermes.toml`
   # will be a string to put into [config.toml](https://hermes.informal.systems/documentation/configuration/configure-hermes.html)
   hermesModuleConfigToml = {modules}:

lib/default.nix

@@ -1,11 +1,12 @@
 {
   inputs,
-  hermes,
+  pkgs,
   ...
-}: let
-  std = inputs.nix-std;
-in {
+}: {
   flake.nixosModules = {
-    hermes = import ../../nixosModules/hermes/default.nix {inherit nix-std hermes;};
+    hermes = import ../../nixosModules/hermes/default.nix {
+      inherit (inputs) nix-std;
+      inherit (pkgs) hermes;
+    };
   };
 }

modules/nixosModules.nix

@@ -1,3 +1,16 @@
+# This module might be slightly confusing, since nixos modules are isntantiated via a "fixed point"
+# which is effectively a loop that accumulates attributes.
+#
+# because of this "fixed point" and lazyness we are able to set the "options"
+# attribute, which declares the schema for the module and is required at the
+# beginning of the loop, and the "config" attribute which is a serialization of
+# the accumulated configuration into a toml file and intuitively happens at the
+# end of the loop
+#
+# TL;DR:
+# - 'options' represents the schema for the hermes configuration module
+# - 'config.toml' represents the a final serialization of the actual configuration into a toml file
+# - for more information on nixos modules see https://nix.dev/tutorials/module-system/module-system.html
 {
   lib,
   nix-std,
@@ -9,10 +22,6 @@ with lib; {
     toml = mkOption {type = types.unique {message = "only one toml output";} types.str;};
   };
   config = {
-    toml = let
-      # remove `null` from toml render
-      sanitizedCfg = filterAttrsRecursive (_: v: v != null) cfg.config;
-    in
-      nix-std.lib.serde.toTOML sanitizedCfg;
+    toml = nix-std.lib.serde.toTOML cfg.config;
   };
 }