move nixlang impls to their own directory tree

configuration.nix

@@ -2,8 +2,8 @@
 
 {
   imports = [
-    ./dynamic.nix
-    ./dynamic-options.nix
+    ./modules/dynamic-overrides.nix
+    ./modules/dynamicism
     "${modulesPath}/profiles/qemu-guest.nix"
   ];
 

default.nix

@@ -15,14 +15,41 @@
 		});
 	in dynix') qpkgs.validStdenvs;
 
+	evalNixos = import (pkgs.path + "/nixos");
+
+	doChange = {
+		option,
+		value,
+	}:
+		assert lib.isList option;
+		assert lib.all lib.isString option;
+	let
+		nixosBefore = evalNixos {
+			configuration = ./configuration.nix;
+		};
+		dynamicBefore = nixosBefore.config.dynamicism.finalSettings;
+
+		nixosAfter = evalNixos {
+			configuration = lib.mkMerge [
+				nixosBefore
+				(lib.setAttrByPath option (lib.mkOverride (-999) value))
+			];
+		};
+
+		dynamicAfter = nixosAfter.config.dynamicism.finalSettings;
+	in {
+
+	};
+
 in dynix.overrideAttrs (final: prev: let
 	self = final.finalPackage;
 in lib.recursiveUpdate prev {
 	passthru = {
 		inherit byStdenv;
-		nixos = import (pkgs.path + "/nixos") {
+		nixos = evalNixos {
 			configuration = ./configuration.nix;
 		};
 		nixos-vm = self.nixos.config.system.build.vm;
+		doChange = builtins.seq self.nixos.config.dynamicism doChange;
 	};
 })

dynamic-options.nix

@@ -1,61 +0,0 @@
-{ pkgs, lib, config, ... }:
-let
-  inherit (lib.modules)
-    mkIf
-  ;
-  inherit (lib.options)
-    mkOption
-    mkEnableOption
-    literalExpression
-    showOption
-  ;
-  t = lib.types;
-  cfg = config.dynamicism;
-
-  settingsFormat = pkgs.formats.yaml { };
-
-  assertionFor = submodName: unitName: let
-    optName = [ "dynamicism" "for" submodName "systemd-services-updated" ];
-  in {
-    assertion = config.systemd.units.${unitName}.enable or false;
-    message = "'${showOption optName}' specified non-existentant unit '${unitName}'";
-  };
-
-  assertionsFor =
-    submodName:
-    submod:
-    lib.map (assertionFor submodName) submod.systemd-services-updated;
-in
-{
-  options.dynamicism.for = mkOption {
-    type = t.attrsOf (t.submoduleWith {
-      modules = [ ./dynamic-submodule.nix ];
-      shorthandOnlyDefinesConfig = false;
-    });
-    default = { };
-  };
-
-  options.dynamicism.finalSettings = mkOption {
-    type = t.attrsOf t.raw;
-    internal = true;
-    readOnly = true;
-  };
-
-  config.assertions = lib.foldlAttrs (acc: name: submod: let
-    next = lib.optionals submod.enable (assertionsFor name submod);
-  in acc ++ next) [ ] cfg.for;
-
-  config.dynamicism.for = {
-    gotosocial = {
-      source-parameters = [ "services" "gotosocial" "settings" ];
-      systemd-services-updated = [ "gotosocial.service" ];
-    };
-  };
-
-    # FIXME: this should be a fold.
-  config.dynamicism.finalSettings = lib.mapAttrs (name: submod: let
-    #optValue = lib.getAttrFromPath submod.
-    # FIXME: this should be a fold.
-    optValue = lib.getAttrFromPath submod.source-parameters config;
-  in optValue) cfg.for;
-}

modules/dynamic-overrides.nix

@@ -12,4 +12,10 @@ lib.mkMerge [
       };
     };
   }
+  {
+    services.gotosocial.settings.application-name = lib.mkOverride 99 "removed herobrine";
+  }
+  {
+    services.gotosocial.settings.application-name = lib.mkOverride 98 "reädded herobrine";
+  }
 ]

modules/dynamicism/default.nix

@@ -0,0 +1,73 @@
+{ pkgs, lib, config, options, ... }:
+let
+  inherit (lib.modules)
+    mkIf
+  ;
+  inherit (lib.options)
+    mkOption
+    mkEnableOption
+    literalExpression
+    showOption
+  ;
+  t = lib.types;
+  cfg = config.dynamicism;
+
+  settingsFormat = pkgs.formats.yaml { };
+
+  assertionFor = submodName: unitName: let
+    optName = [ "dynamicism" "for" submodName "systemd-services-updated" ];
+  in {
+    assertion = config.systemd.units.${unitName}.enable or false;
+    message = "'${showOption optName}' specified non-existentant unit '${unitName}'";
+  };
+
+  assertionsFor =
+    submodName:
+    submod:
+    lib.map (assertionFor submodName) submod.systemd-services-updated;
+
+  finalSettingsFor = { ... }@submod: lib.foldl (acc: optPath: let
+    next =
+      assert lib.isList optPath;
+      lib.setAttrByPath optPath (lib.getAttrFromPath optPath config);
+  in lib.recursiveUpdate acc next) { } submod.source-options;
+in
+{
+  options.dynamicism = {
+    for = mkOption {
+      type = t.attrsOf (t.submoduleWith {
+        modules = [ ./submodule.nix ];
+        shorthandOnlyDefinesConfig = false;
+      });
+      default = { };
+    };
+
+    finalSettings = mkOption {
+      type = t.attrsOf t.raw;
+      internal = true;
+      readOnly = true;
+      description = ''
+        Attrset of each `source-options` tree to their actual values.
+      '';
+    };
+  };
+
+  config.assertions = lib.foldlAttrs (acc: name: submod: let
+    next = lib.optionals submod.enable (assertionsFor name submod);
+  in acc ++ next) [ ] cfg.for;
+
+  config.dynamicism.for = {
+    gotosocial = {
+      source-options = [
+        "services.gotosocial.settings"
+      ];
+      systemd-services-updated = [
+        "gotosocial.service"
+      ];
+    };
+  };
+
+  config.dynamicism.finalSettings = lib.foldlAttrs (acc: name: { ... }@submod: let
+    next = finalSettingsFor submod;
+  in lib.recursiveUpdate acc next) { } config.dynamicism.for;
+}

modules/dynamicism/submodule.nix

@@ -1,6 +1,5 @@
 {
   name,
-  pkgs,
   lib,
   config,
   ...
@@ -15,16 +14,19 @@ let
     literalExpression
   ;
   t = lib.types;
+
+  /** Either a list of strings, or a dotted string that will be split. */
+  convenientAttrPath = t.coercedTo t.str (lib.splitString ".") (t.listOf t.str);
 in
 {
   options = {
-    enable = mkEnableOption "Dynamicism for ${name}";
+    enable = mkEnableOption "Enable dynamicism for '${name}'";
 
-    source-parameters = mkOption {
-      type = t.listOf t.str;
-      description = "An attrpath of the NixOS option this dynamicism uses";
+    source-options = mkOption {
+      type = t.listOf convenientAttrPath;
+      description = "A list of attrpaths of the NixOS option the dynamicism for '${name}' uses";
       example = literalExpression ''
-        [ "services" "gotosocial" "settings" ]
+        [ [ "services" "gotosocial" "settings" ] "services.nginx.settings" ]
       '';
     };
 

src/args.rs

@@ -56,10 +56,15 @@ pub struct AppendCmd {
     pub value: Arc<str>,
 }
 
+#[derive(Debug, Clone, PartialEq, clap::Parser)]
+pub struct DeltaCmd {}
+
 #[derive(Debug, Clone, PartialEq, clap::Subcommand)]
 #[command(flatten_help = true)]
 pub enum Subcommand {
     Append(AppendCmd),
+    // TODO: rename
+    Delta(DeltaCmd),
 }
 
 #[derive(Debug, Clone, PartialEq, clap::Parser)]
@@ -70,6 +75,7 @@ pub struct Args {
     #[arg(long, global(true), default_value = "auto")]
     pub color: ColorChoice,
 
+    // FIXME: default to /etc/configuration.nix, or something?
     #[arg(long, global(true), default_value = "./configuration.nix")]
     pub file: Arc<OsStr>,
 

src/lib.rs

@@ -34,7 +34,7 @@ pub(crate) mod prelude {
 use prelude::*;
 
 pub mod args;
-pub use args::{AppendCmd, Args};
+pub use args::{AppendCmd, Args, DeltaCmd};
 mod color;
 pub use color::{_CLI_ENABLE_COLOR, SHOULD_COLOR};
 pub mod line;
@@ -49,6 +49,11 @@ use crate::source::SourceFile;
 
 pub const ASCII_WHITESPACE: &[char] = &['\t', '\n', '\x0C', '\r', ' '];
 
+#[tracing::instrument(level = "debug")]
+pub fn do_delta(args: Arc<Args>, delta_args: DeltaCmd) -> Result<(), BoxDynError> {
+    todo!();
+}
+
 #[tracing::instrument(level = "debug")]
 pub fn do_append(args: Arc<Args>, append_args: AppendCmd) -> Result<(), BoxDynError> {
     let filepath = Path::new(&args.file);

src/main.rs

@@ -26,10 +26,13 @@ fn main_wrapped() -> Result<(), Box<dyn StdError + Send + Sync + 'static>> {
 
     tracing::debug!("Parsed command-line arguments: {args:?}");
 
-    use dynix::args::Subcommand::*;
-    match &args.subcommand {
-        Append(append_args) => dynix::do_append(args.clone(), append_args.clone())?,
-    };
+    {
+        use dynix::args::Subcommand::*;
+        match &args.subcommand {
+            Append(append_args) => dynix::do_append(args.clone(), append_args.clone())?,
+            Delta(delta_args) => dynix::do_delta(args.clone(), delta_args.clone())?,
+        };
+    }
 
     Ok(())
 }