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Simple asynchronous functions

The snippet demonstrates how to compose simple asynchronous functions and how to use try .. with to handle exceptions in asynchronous workflows.

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// Simple asynchronous function that capitalizes a string
let capitalizeAsync (s:string) = async {
  return s.ToUpper() }

// Simple asynchronous function that appends "Hello" to front
let addHello (s:string) = async {
  return "Hello " + s + "!" }

// Asynchronous function that calls two other asynchronous 
// functions asynchronously and uses 'try .. with' to 
// handle exceptions that may occur in a standard way
let processWord (s:string) = async {
  try
    let! cap = capitalizeAsync(s)
    let! hcap = addHello(cap)
    return hcap
  with e ->
    return "Exception occurred!" }
val capitalizeAsync : s:string -> Async<string>

Full name: Script.capitalizeAsync
val s : string
Multiple items
val string : value:'T -> string

Full name: Microsoft.FSharp.Core.Operators.string

--------------------
type string = System.String

Full name: Microsoft.FSharp.Core.string
val async : AsyncBuilder

Full name: Microsoft.FSharp.Core.ExtraTopLevelOperators.async
System.String.ToUpper() : string
System.String.ToUpper(culture: System.Globalization.CultureInfo) : string
val addHello : s:string -> Async<string>

Full name: Script.addHello
val processWord : s:string -> Async<string>

Full name: Script.processWord
val cap : string
val hcap : string
val e : exn
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More information

Link:http://fssnip.net/3q
Posted:13 years ago
Author:Tomas Petricek
Tags: async , asynchronous , workflows , try , exception

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