How do I declare a generic parameter in F#?

Question

Given the following code:

let DisplayImpl logger data =
    data |> Seq.iter logger
    printfn ""

let Working =
    DisplayImpl (printfn "%O") [1;2;3]
    DisplayImpl (printfn "%O") ["a";"b";"c"]

let NotWorking display =
    display (printfn "%O") [1;2;3]
    display (printfn "%O") ["a";"b";"c"]
                            ~~~ ~~~ ~~~

The last line gives the error: This expression was expected to have type int but here has type string

I thought the following might work, but it doesn't:

let StillNotWorking (display: ('a -> unit) -> seq<'a> -> unit) =

My question is, how do I define the NotWorking function so that the display parameter stays generic within the function?