gistfile1.py

from werkzeug import wrappers


def application(request):
    request > get("/") > do_response()
    request > get("/msg") > say_hello()

# # WARNING
#
# Don't judge me. :-)
#
# Seriously, the code below this is just proof of concept code that
# enables the application function to actually run.


class HttpResponse(BaseException):
    pass


class Http405(HttpResponse):
    def do(self, environ, start_response):
        return wrappers.Response(status=405)(environ, start_response)


class Http404(HttpResponse):
    def do(self, environ, start_response):
        return wrappers.Response(status=404)(environ, start_response)


def route(path, methods="GET"):
    if not type(methods) is list:
        methods = [methods, ]

    class Route(object):
        def __lt__(self, request):
            if not request.path == path:
                return False
            if not request.method in methods:
                raise Http405
            request.route = self
            self.request = request
            return True

    return Route()


def get(path):
    return route(path, methods=["GET"])


class Response(HttpResponse):
    def __lt__(self, route):
        self.request = route.request
        raise self

    def do(self, environ, start_response):
        return wrappers.Response("Hello!\n", mimetype="text/html")(environ, start_response)


def do_response():
    return Response()


def say_hello():
    class HelloResponder(Response):
        def do(self, environ, start_response):
            who = self.request.args.get('who', 'World')
            return wrappers.Response(
                "Hello, %s!\n" % who,
                mimetype="text/html"
            )(environ, start_response)
    return HelloResponder()


if __name__ == '__main__':

    from werkzeug.serving import run_simple

    def app(environ, start_response):
        request = wrappers.Request(environ)
        try:
            application(request)
        except HttpResponse as response:
            return response.do(environ, start_response)

    run_simple("127.0.0.1", 1981, app, use_reloader=True)

This is in a better form here https://github.com/tswicegood/steinie