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I have a windows forms button and I attach a function to its Click event, how can I make the function evaluate to the unit type?

let button = new Button()

button.Click.Add(buttonClicked)

 

let buttonClicked (e:System.EventArgs) =

let d = MessageBox.Show(e.ToString())

printf ""          // stupid way of forcing the expression to evaluate to the unit type .. (?)

 

Any suggestions?

Hi,

"()" is used to represent unit.  It's very general and can be used in a number of situations, for example;

> let x = fun () -> ();;
val x : unit -> unit
> x;;
val it : (unit -> unit) = <fun:clo@0>
> x();;
val it : unit = ()

Cheers,

Andy

thank you for the quick (and correct!) reply :)

You probably want to use the ignore function to make something evealuate to the unit type.

let buttonClicked (e:System.EventArgs) =
    MessageBox.Show(e.ToString()) |> ignore

I'm probably going to start sounding like a broken record, but this is covered at the beginning of chapter 4 in my book:
http://www.amazon.com/dp/1590597575?tag=strangelights-20&camp=14573&creative=327641&linkCode=as1&creativeASIN=1590597575&adid=0F4QKB6A95B2Z4NW1BFN

---

Robert Pickering, MVP
http://strangelights.com