Local Mailbox Processor

CloudAgent-1.fs

// Our simple domain model
type Priority =
| Low
| Normal
| High

type Message = {
    Text : string
    Priority : Priority
}

type MessageCollection =
    { Count : int
      Messages : Message list }

type Command =
| Record of Message // Add a new message to file
| Clear // Wipe out all messages

/// Create an Mailbox Processor for a specific actor.
let CreateActor (ActorKey name) =
    MailboxProcessor.Start(fun mailbox ->
        let messageStore = GetMessageStore name
        let rec loop data =
            async {
                // Wait asynchronously until we get a message
                let! message = mailbox.Receive()

                // Process the message                
                match message with
                | Clear ->
                    // Delete file and loop around.
                    messageStore.DeleteIfExists()
                    return! loop { Count = 0; Messages = [] }
                | Record message ->
                    // Append the new message to file.
                    let updatedData =
                        { data with
                            Count = data.Count + 1
                            Messages = data.Messages @ [ message ] }
                    messageStore.SetData(updatedData)
                    return! (loop updatedData)
            }

        // Start by loading the existing data, then loop indefinitely
        let data = defaultArg (messageStore.GetData()) { Count = 0; Messages = [] }
        loop data)
        
// Create an actor and post to it locally
let isaac = CreateActor "isaac"
isaac.Post(Record { Text = "Hello"; Priority = Priority.Low })