Middleware and accept overlap a bit ? Need more freedom for composition ?

[craff]

• Both optional argument do some extra treatment on handler.
• Some middleware may want look at the request first or last and modify the response first or last, but it is not clear how to do that. Either go back to a single middleware + accept done before and then, let the user compose middleware functions himself (it is me who proposed lists ?). Provide a few composition operators ?

[c-cube]

Yes, accept predates middlewares, it's a bit redundant. However it's also simpler to use for basic cases, I think.

Middlewares can already look at the request first, or modify the response last. They can't modify the response first because it simply doesn't exist before the inner layer returns a response. An example of middleware that modifies both request and response is the camlzip middleware. How it works: the middleware takes handler and req and resp (a continuation that will eat the response); it can modify req before passing it to handler if needed; it can intercept the response from the handler before passing it to resp.

Composition operators on middlewares is clearly a possibility, but the question is: what more than the list do you need? Choice? I'm open to the idea but I think it'd be good to have concrete examples of use cases.

[c-cube]

I think the overlap is fine for now.