F# method to insert, update, or delete events in a dictionary

Question

I have the following code:

    member this.ProcessEvent(sourceStream: OrderResponse) =          
       match sourceStream.Action with
        | Action.Partial
        | Action.Insert ->
            sourceStream.Data
            |> Seq.iter (fun x -> this.orderState.[x.OrderId] <- this.ConvertFullOrder x)
        | Action.Update ->
            sourceStream.Data
            |> Seq.iter (fun x -> this.orderState.[x.OrderId] <- this.UpdateOrder x this.orderState.[x.OrderId])
        | Action.Delete ->
            sourceStream.Data
            |> Seq.iter (fun x -> this.orderState.Remove(x.OrderId) |> ignore)
        | _ -> ()

It is processing a list of events and an action. The data is processed and stored in a dictionary. The action tells to insert, update or delete some of the records and applies to all the events received in the same message.

For each case, I iterate through the sourceStream.Data list.

Is there a better / more readable way where I can declare I am going to process that list and then, based on the Action, have different code? this would allow to remove the multiple sourceStream.Data |> bits and specify it only once.

Answer 1

You have probably found a good solution long time ago, but here is my suggestion:

member this.ProcessEvent(sourceStream: OrderResponse) =          
    let handler: (Order -> unit) = 
        match sourceStream.Action with
        | Action.Partial
        | Action.Insert -> (fun x -> this.orderState.[x.OrderId] <- this.ConvertFullOrder x)
        | Action.Update -> (fun x -> this.orderState.[x.OrderId] <- this.UpdateOrder x this.orderState.[x.OrderId])
        | Action.Delete -> (fun x -> this.orderState.Remove(x.OrderId) |> ignore)
        | _ -> (fun x -> ())

    sourceStream.Data |> Seq.iter handler

I'm not sure. what type x has, so for the illustration I just call it Order in the handler definition.