move custom type into custom lib

default.nix

@@ -8,7 +8,11 @@
 , lib ? import "${sources.nixpkgs}/lib"
 }:
 let
-  lib' = final: prev: import ./lib.nix { lib = final; };
+  lib' = final: prev:
+    let
+      new = import ./lib.nix { lib = final; };
+    in
+    new // { types = prev.recursiveUpdate prev.types new.types; };
   lib'' = lib.extend lib';
 in
 {

lib.nix

@@ -37,4 +37,48 @@ rec {
 
   indent = prefix: s:
     join "\n" (map (x: if x == "" then x else "${prefix}${x}") (splitLines s));
+
+  types = rec {
+    collection = elemType:
+      let
+        unparenthesize = class: class == "noun";
+        desc = type:
+          types.optionDescriptionPhrase unparenthesize type;
+        desc' = type:
+          let
+            typeDesc = lib.types.optionDescriptionPhrase unparenthesize type;
+          in
+          if type.descriptionClass == "noun"
+          then
+            typeDesc + "s"
+          else
+            "many instances of ${typeDesc}";
+      in
+      lib.types.mkOptionType {
+        name = "collection";
+        description = "separately specified ${desc elemType} for a collection of ${desc' elemType}";
+        merge = loc: defs:
+          map
+            (def:
+              let
+                merged = lib.mergeDefinitions
+                  (loc ++ [ "[definition ${toString def.file}]" ])
+                  elemType
+                  [{ inherit (def) file; value = def.value; }];
+              in
+              if merged ? mergedValue then merged.mergedValue else merged.value
+            )
+            defs;
+        check = elemType.check;
+        getSubOptions = elemType.getSubOptions;
+        getSubModules = elemType.getSubModules;
+        substSubModules = m: collection (elemType.substSubModules m);
+        functor = (lib.defaultFunctor "collection") // {
+          type = collection;
+          wrapped = elemType;
+          payload = { };
+        };
+        nestedTypes.elemType = elemType;
+      };
+  };
 }

structure/default.nix

@@ -5,7 +5,7 @@ let
     types
     ;
   cfg = config;
-  types' = import ./types.nix { inherit lib; } // {
+  types' = {
     article = { config, collectionName, ... }: {
       imports = [ types'.page ];
       options = {
@@ -115,7 +115,7 @@ in
           };
           entry = mkOption {
             description = "An entry in the collection";
-            type = types'.collection (types.submodule ({
+            type = types.collection (types.submodule ({
               _module.args.collection = config.entry;
               _module.args.collectionName = name;
               imports = [ config.type ];

structure/types.nix

@@ -1,47 +0,0 @@
-{ lib, ... }:
-let
-  inherit (lib) types;
-in
-rec {
-  collection = elemType:
-    let
-      unparenthesize = class: class == "noun";
-      desc = type:
-        types.optionDescriptionPhrase unparenthesize type;
-      desc' = type:
-        let
-          typeDesc = types.optionDescriptionPhrase unparenthesize type;
-        in
-        if type.descriptionClass == "noun"
-        then
-          typeDesc + "s"
-        else
-          "many instances of ${typeDesc}";
-    in
-    types.mkOptionType {
-      name = "collection";
-      description = "separately specified ${desc elemType} for a collection of ${desc' elemType}";
-      merge = loc: defs:
-        map
-          (def:
-            let
-              merged = lib.mergeDefinitions
-                (loc ++ [ "[definition ${toString def.file}]" ])
-                elemType
-                [{ inherit (def) file; value = def.value; }];
-            in
-            if merged ? mergedValue then merged.mergedValue else merged.value
-          )
-          defs;
-      check = elemType.check;
-      getSubOptions = elemType.getSubOptions;
-      getSubModules = elemType.getSubModules;
-      substSubModules = m: collection (elemType.substSubModules m);
-      functor = (lib.defaultFunctor "collection") // {
-        type = collection;
-        wrapped = elemType;
-        payload = { };
-      };
-      nestedTypes.elemType = elemType;
-    };
-}