Add an overlay to the flake.

flake.nix

@@ -57,11 +57,45 @@
           pkgs = import nixpkgs {
             inherit system overlays;
           };
+          appliedOverlay = self.overlays.default pkgs pkgs;
+        in
+        rec {
+          default = all;
+          all = pkgs.symlinkJoin {
+            name = "all";
+            paths = [
+              library
+              devTools
+              wasm_bundler
+              wasm_web
+            ];
+          };
+          inherit (appliedOverlay.organic)
+            library
+            devTools
+            wasm_bundler
+            wasm_web
+            ;
+          docker_env = pkgs.buildEnv {
+            name = "organic";
+            paths = with pkgs; [
+              appliedOverlay.organic.devTools
+              bash
+              uutils-coreutils-noprefix
+              # toybox # Smaller than uutils-coreutils?
+            ];
+          };
+        }
+      );
+      overlays.default = final: prev: {
+        organic = final.lib.makeScope final.newScope (
+          organicScope:
+          let
             build_wasm =
               {
                 bindgenTarget ? null,
               }:
-            (pkgs.callPackage ./nix/package.nix {
+              (organicScope.callPackage ./nix/package.nix {
                 targetBins = [
                   "wasm"
                 ];
@@ -73,7 +107,7 @@
                   old:
                   let
                     bindgen_command = [
-                    "${pkgs.wasm-bindgen-cli}/bin/wasm-bindgen"
+                      "${final.wasm-bindgen-cli}/bin/wasm-bindgen"
                       "--target"
                       bindgenTarget
                       "--out-dir"
@@ -83,7 +117,7 @@
                   in
                   {
                     postBuild = ''
-                    ${pkgs.lib.escapeShellArgs bindgen_command}
+                      ${final.lib.escapeShellArgs bindgen_command}
                     '';
 
                     installPhase = ''
@@ -93,17 +127,8 @@
                   }
                 );
           in
-        rec {
+          {
-          all = pkgs.symlinkJoin {
+            library = (organicScope.callPackage ./nix/package.nix { buildLib = true; }).overrideAttrs (
-            name = "all";
-            paths = [
-              library
-              devTools
-              wasm_bundler
-              wasm_web
-            ];
-          };
-          library = (pkgs.callPackage ./nix/package.nix { buildLib = true; }).overrideAttrs (
               old:
               let
               in
@@ -114,7 +139,7 @@
                 '';
               }
             );
-          devTools = pkgs.callPackage ./nix/package.nix {
+            devTools = organicScope.callPackage ./nix/package.nix {
               targetBins = [
                 "parse"
                 "compare"
@@ -123,17 +148,8 @@
             };
             wasm_bundler = build_wasm { bindgenTarget = "bundler"; };
             wasm_web = build_wasm { bindgenTarget = "web"; };
-          docker_env = pkgs.buildEnv {
-            name = "organic";
-            paths = with pkgs; [
-              devTools
-              bash
-              uutils-coreutils-noprefix
-              # toybox # Smaller than uutils-coreutils?
-            ];
-          };
-          default = all;
           }
         );
       };
+    };
 }