(yada ...) returns you a handler, which you can modify however you wish prior to passing it to your webserver. You can use assoc, update-in etc. The docs are getting updated but yada is still in active development. Current focus is completing Swagger (much improved now!), CORS and user interceptors

Ok I see, CORS/swagger are very useful for public APIs/SaaS products (my use case exactly). So associng to (yada ...) for now (synchronously only ?), will be replaced by user interceptors when it is ready, correct ?

Even if you choose not to try yada do let me know your requirements and I will steer towards supporting them. I really want to start focussing on real-world use cases.