modules: move local functions to extended library

lib/build.nix

@@ -0,0 +1,15 @@
+{
+  # TODO: give those section indicators
+  # maybe using mkSection?
+  wrapLuaConfig = {
+    luaConfigBefore,
+    luaConfig,
+    luaConfigAfter,
+  }: ''
+    lua << EOF
+    ${luaConfigBefore}
+    ${luaConfig}
+    ${luaConfigAfter}
+    EOF
+  '';
+}

lib/dag.nix

@@ -126,4 +126,10 @@ in {
       else abort ("Dependency cycle in ${name}: " + toJSON sortedDag);
   in
     result;
+
+  # Create a section in the final output
+  mkSection = section: ''
+    -- SECTION: ${section.name}
+    ${section.data}
+  '';
 }