static IResourceLoader resourceLoaderFromDir(File dir) {
  SS titles = cast safeUnstructure(loadTextFile(newFile(dir, "snippet-titles.struct")));
  assertNempty("Snippet titles", titles);
  Map<S, Int> types = cast safeUnstructure(loadTextFile(newFile(dir, "snippet-types.struct")));

  ret new IResourceLoader {
    public S loadSnippet(S snippetID) {
      ret loadTextFile(newFile(dir, psI(snippetID) + ".text"));
    }
    
    public S getTranspiled(S snippetID) {
      S src = loadTextFile(newFile(dir, psI(snippetID) + ".transpiled"));
      if (empty(src))
        print("Warning: Transpilation for " + snippetID + " not found");
      ret src;
    }
    
    public int getSnippetType(S snippetID) {
      ret or0(types.get(fsI(snippetID)));
    }
    
    public S getSnippetTitle(S snippetID) {
      ret titles.get(fsI(snippetID));
    }
    
    public File loadLibrary(S snippetID) {
      long id = psI(snippetID);
      if (isImageServerSnippet(id)) 
        ret assertIsFile(oneOfTheFiles(
          newFile(dir, id + ".png"),
          newFile(id + ".gif")));
      else
        ret assertIsFile(newFile(dir, id + ".bin"));
    }
  };
}