> Take Firefox for example. It has extensions, but they're intrinsically limited by the fact that they're sandboxed and can only interact with the browser throu

> Take Firefox for example. It has extensions, but they're intrinsically limited by the fact that they're sandboxed and can only interact with the browser through a limited API. That's design, a choice. It used to be different in old Firefox, and other browsers are different in that aspect even today. But to be fair, I mainly meant the page-context, not the application-context. Most normal web browser support userscript, bookmarklets and debugging some way or another. Or should I say, still. Because this is a bit in decline. And if you take something like web- or electron-apps, the page-context becomes the app itself. All just a matter of implementation and architecture. > There fundamentally is nothing you can't do through the configuration. You can't patch the C-core, can you? Another necessary implementation-detail. > Precisely because Lisp is a dynamic meta-programming language, which is the ideal paradigm for this. It was ideal when Emacs was created. Today, we have many alternatives. > You gain nothing in extensibility, Except more ability, more heritage, more users... At the end, it's all a matter of managing the tradeoffs, the implementation-details.