anchor.diff:      let IsNotEmpty msg p =
           Is (fun x -> x <> "") msg p
   
  -    let IsMatch (re: string) msg p =
  -        Is (RegExp(re).Test) msg p
  +    let IsMatch (regexp: string) msg p =
  +        Is (RegExp(regexp).Test) msg p
   
       let MapValidCheckedInput msg p =
           p |> Form.MapResult (fun res ->
  
positive.code:             render = fun r -> r var
          }
  
      let Yield value =
          YieldVar (Var.Create value)
  
      let YieldFailure () =
          let var = Var.Create JS.Undefined<_> :> Var<_>
  
negative.code:             | Success (Failure mx) -> Failure mx
              | Success (Success x) -> Success (f x)
  
      static member Bind (f: 'T -> Result<'U>) (r: Result<'T>) : Result<'U> =
          match r with
          | Failure m -> Failure m
          | Success x -> f x
  
  