| Interface | Description | 
|---|---|
| Future | 
 A future is an abstraction over the eventual result of a possibly asynchronous computation. 
 | 
| Future.Observer | 
 Simple interface for a future observer / callback. 
 | 
| Class | Description | 
|---|---|
| AssignedFuture | 
 Convenience implementation for pre-set futures. 
 | 
| Promise | 
 A promise object is used to abstract over possibly asynchronous computations. 
 |