D.: The F# asynchronous programming model

With one breath, with one flow, you will know, asynchronicity. [ The Police, 1983, adapted] Abstract. We describe the asynchronous programming model in F#, and its applications to reactive, parallel and concurrent programming. The key feature combines a core language with a non-blocking modality to author lightweight asynchronous tasks, where the modality has control flow constructs that are syntactically a superset of the core language and are given an asynchronous semantic interpretation. This allows smooth transitions between synchronous and asynchronous code and eliminates callback-style treatments of inversion of control, without disturbing the foundation of CPU-intensive programming that allows F # to interoperate smoothly and compile efficiently. An adapted version of this approach has recently been announced for a future version of C#.