timemachine.fs

timemachine.fs

type AsyncResultBuilder ( timeMachine ) =
    let mutable map = emptyMap ()
    
    let mkOperation generator = 
        let intercept = generator ()
        let cmds = side_effect_connection_ctx ()
        let cmdList = sql_to_send cmds
        map <- map @ cmdList
        intercept
        
    let collect () = async {
        return! AsyncSeq.iter <| fun cmd -> async {
            let timestamp t = typeof<TimeStamp>.IsAssignableFrom t
            let dt = lens_for cmd |> Seq.filter timestamp
            let t = - timeMachine.warp + timeMachine.lastWarp
            let cmds = side_effect_connection_ctx ()    
            cmds.run cmd
            let sql = mk_sql_timestamp dt <% dt - t %>
            cmds.run <| sql cmd.param
            timeMachine.commit ()
            map <- emptyMap ()
        }
    }

    member __.Return value : Async<Result<'a option, 'b>> = ok value
    member __.ReturnFrom (asyncResult: Async<Result<'a option, 'b>>) = asyncResult
    member __.Zero () : Async<Result<unit option, 'b>> = __.Return ()
    member __.Delay ( generator: unit -> Async<Result<'a option, 'b>> ) : Async<Result<'a option, 'b>> =
        mkOperation async.Delay generator
    member __.Bind ( asyncResult: Async<Result<'a option, 'c>>, binder: 'a -> Async<Result<'b option, 'c>> ) : Async<Result<'b option, 'c>> =
        asyncResult |> bind binder
    member __.TryWith ( asyncResult: Async<Result<'a option, 'b>>, catchHandler: exn -> Async<Result<'a option, 'b>> ) : Async<Result<'a option, 'b>> =
        async.TryWith ( asyncResult, catchHandler )
    member __.TryFinally ( asyncResult : Async<Result<'a option, 'b>>, compensation: unit -> unit ) : Async<Result<'a option, 'b>> =
        async.TryFinally ( asyncResult, compensation )
    member __.Using ( resource: 'T when 'T :> System.IDisposable, binder: 'T -> Async<Result<'a option, 'b>> ) : Async<Result<'a option, 'b>> =
        collect async.Using ( resource, binder )