>I'll go back to my earlier point, which I think you've illustrated fairly well, which is that well-written Java code tends to be more concise and less verbose than Python (and friends). Our two examples are nearly identical in terms of meaningful lines of code, but in the Python example you have to ask for marshaling.

That's only an API wart. It'd be possible to elide that pretty easily if someone wanted to write a library to do that.

I could write a library function or flask extension or whatnot that resulted in

    @app.myroute('thing', method=['POST')
    def handle(thing: Thing):
        # work with thing

and the unmarshalling is handled by the decorator and type annotation. Your prime example of java being less verbose is a wash. They're at best equally verbose, and you picked something that java has libraries specifically catered toward.

>I'll also point out that flask (which I use myself for python webapps) handlers are forced to interact with flask-specific objects and therefore are obnoxious to test

Huh? Here's an example of a test from the flask docs[0] that makes a request and checks the result.

    def test_empty_db(client):
        rv = client.get('/')
        assert b'No entries here so far' in rv.data

Its a simple example, but having written tests for flask myself

1. There should be minimal logic in the handler. You should defer most logic to a library function, you can also not use the decorator form and instead declare `app.route('/path')(function)` and just test function itself.

2. Even testing the handlers and doing end to end stuff with a running server isn't that hard. I'm not sure what you're experience was, but my guess is you weren't leveraging existing libraries.

>This is one of the big advantages of moving marshaling "out" of your program code.

Here's the implementation of that:

    def myroute(self, *args, **kwargs):
        def wrapper(f):
            @self.route(*args, **kwargs) 
            def new_route(*args):
                arg, schema  = f.__annotations__.items()
                parsed = schema.load(request.form)
                return f(arg=parsed)
            return new_route
         return wrapper

And now if you've tested that, you no longer need to worry about marshalling in your program code.

Flask however is relatively generic, it can handle things that your java examples can't, like an endpoint where you don't know the schema, which might happen if you're doing something like hosting a user-provided function or something of that nature (I implemented an AWS-lambda style thing in a hackathon with that). Something like

    @route('/user_endpoint')
    def handle():
        return convert_to_html_response(user_function(**request.form))

This was really easy to implement. I doubt it would have been as concise in Java (and note that you are leaving validation to the user here, so none needs to be done by you).

Flask lets you do that. If you want to restrict yourself to schematized requests, you have more information and can make more assumptions, but flask isn't a REST framework, its a generic web framework. If you want to restrict yourself to something with known schemas, you can do that pretty concisely[1], even when dealing with relatively complex marshalling (and you can do it outside of your logical code under test via decorators).

[0]: http://flask.pocoo.org/docs/1.0/testing/

[1]: https://flask-restful.readthedocs.io/en/0.3.6/fields.html