AsyncResultSample.fsx

#load @"paket-files/fsprojects/Chessie/src/Chessie/ErrorHandling.fs"

open System
open Chessie.ErrorHandling

type Person = { FirstName: string; LastName: string }

let id1 = Guid.NewGuid()
let id2 = Guid.NewGuid()

let getAsync id =
    let people = 
        [(id1, { FirstName = "Don"; LastName = "Syme" })
         (id2, { FirstName = "Martin"; LastName = "Odersky" })] 
        |> Map.ofList
    let get id: Result<Person, string> = 
        people |> Map.tryFind id |> Trial.failIfNone "not found"
    get id |> Async.singleton |> AR

let eventuallyErrorOrTwoDudes: AsyncResult<Person list, string> = 
    asyncTrial {
        let! don = getAsync id1
        let! martin = getAsync id2 // can this be run in parallel?
        return [don; martin] }

printfn "%A" (getAsync id1 |> Async.ofAsyncResult |> Async.RunSynchronously)
printfn "%A" (getAsync (Guid.NewGuid()) |> Async.ofAsyncResult |> Async.RunSynchronously)
printfn "%A" (eventuallyErrorOrTwoDudes |> Async.ofAsyncResult |> Async.RunSynchronously)