anchor.diff:      (http/ok promise {:content-type "text/plain"})))
   ----
   
  -Thanks to the *future* library internals, we can use it with link:http://fff[cats] `mlet` macro,
  -that allows us structure pure async code in a synchronous way:
  +Thanks to the *future* library internals, we can use it with 
  +link:https://github.com/funcool/cats[cats] `mlet` macro, that allows us structure pure async 
  +code in a synchronous way:
   
   [source, clojure]
   ----
  
positive.code: === Promises
  
  Promises is an other abstraction supported out of the box in _catacumba_. It comes from the
  link:http://fff[futura library] and is build on top of JDK8 _CompletableFuture_.
  
  Sometimes, yo do not need send a chunked stream to the clien, but your "bussines logic" is defined
  with asynchronous friendly api using promises (or something similar). In this case, with _catacumba_
  
negative.code: addopts a flexible and extensible way for make easy for the user adapt it to hes needs and hes
  abstractions.
  
  The main abstraction are defined in the link:https://github.com/funcool/futura[futura library], 
  that provides basic building blocks for promise like abstractions and stream abstraction.
  
  The link:https://github.com/funcool/futura[futura library] instead of reinvent the wheel, is build 
  up on existing implementations such as:
  
  * _JDK8 CompletableFuture_ for *promise* abstraction.
  * _Reactive Streams_ for the *stream* abstraction.
  