title: future and for yield syntax async or sync?
body: <p>I've been using Scala for quite some time now and I am stumbling upon
  a very essential question regarding the usage of future with for-yield comprehension.</p>
  
  <p>The for-yield syntax is just a syntactic sugar that simplifies a chain of flatMap/map. Futures are supposed to be a wrapper for async, but it seems like the usage of flatMap/map plays a more synchronous role as it seemingly 'waits' on the result of the previous future call to be computed so it can be manipulated. So this becomes more confusing all of a sudden and makes me return to this fundamental question. Futures are async, but are the usage of map/flatmap (for-yield) also async even though it allows sequential operation inside for-yield? </p>
  
  <p>Any help will be greatly appreciated.</p>