Asynchronous F# programming sandbox.

• orthogonal concepts:

  • concurrency
  • parallelism
  • asynchrony - not at the same time

• Async<T> type represents a composable asynchronous operations

• Async module contains functions which:

  • schedule
  • compose
  • transform

  asynchronous operations.

  Examples:

  • Async.RunSynchronously
  • Async.Start
  • Async.StartChild
  • Async.Catch

• async { } - computation expression/asynchronous expression. All expressions of such form are of type Async<T> for some T. source
• expr := async { aexpr } - complete syntax for asynchronous expressions.
• selected aexpr examples:
  • do! - execute async (Async<unit>).
  • let! - execute and bind async (Async<T>).
  • return! expr - tailcall to async
  • return expr - return result of async expression
• Task<T> -> Async<T> - interop translation of C# Task<T> to F# Async<T>.
• asynchronous function - normal function or method, but returning an asynchronous computation. It is common for asynchronous functions to have their entire bodies enclosed in async { }.
• cancellation:

  • C# CancellationTokenSource and CancellationToken are both supported.

  • cancellation tokens are implicitly propagated through the execution of an asynchronous operation.

  • Cancellation tokens are provided at the entry point to the execution of an asynchronous computation, e.g.:

    • Async.RunSynchronously
    • Async.StartImmediate
    • Async.Start

    reference: https://stackoverflow.com/questions/15284209/async-start-vs-async-startchild

• exceptions:
  • basic exceptions
  • nested exceptions
  • nested cancellations.

• Async programming in F#
• The F# Asynchronous Programming Model
• Async in C# and F# Asynchronous gotchas in C#
• F# Async Guide