Can I Access Parameters of a Computation Expression?

Question

Is it possible to create methods or stand-alone functions in a computation expression that can later be used by one of the canonical methods of a computation expression?

I want something like this:

type FormletBuilder(ctx : HttpContext) =

    let get_int = 
        match Int32.TryParse (ctx.Request.["foo"]) with
        | (true, n) -> Some n
        | _ -> None

    //similar definitions for get_date, get_non_empty_str, etc...

    member x.Bind (read : 'a option, f : 'a -> option 'a) =
        match read with
        | Some x -> f(x)
        | None -> None      

    member x.Return (obj) = Some obj
    member x.Zero () = None



    let person = formlet ctx {

        let! id = get_int "id"
        let! name = get_non_empty_str "fullname"

        return Person(id, name)
    }

But the compiler complains that get_int is not defined.

Answer 1

let bindings in class definitions are always private. You can define a member instead.

For an easy solution, you could do:

let formlet = FormletBuilder(ctx)
let person = formlet {
    let! id = formlet.get_int "id"
    ...
}