type HeapNode<'a> =
    { priority : int
      value : 'a
      parent : Heap<'a>
      left : Heap<'a>
      right : Heap<'a> }

and Heap<'a> =
    | Empty
    | Node of HeapNode<'a>

module Heap =

    let private getWith f h =
        match h with
        | Empty -> failwith "empty"
        | Node hn -> f hn

    let priority h = h |> getWith (fun hn -> hn.priority)

    let value h = h |> getWith (fun hn -> hn.value)