type Name = string;;
type Sex =  | M // male
            | F // female
type YearOfBirth = int;;
type FamilyTree = P of Name * Sex * YearOfBirth * Children
and Children = FamilyTree list

let fred = P("Fred",M,1970,[])
let joan = P("Joan",F,1975,[])
let may = P("May",F,1945,[fred;joan])


let stanley = P("Stanley",M,1975,[])

let peter = P("Peter",M,2005,[])
let bob = P("Bob",M,2008,[])
let eve = P("Eve",F,2010,[])
let mary = P("Mary",F,1980,[peter;bob;eve])
let jane = P("Jane",F,1985,[])
let joe = P("Joe",M,1950,[stanley;mary;jane])

let paul = P("Paul",M,1955,[])
let larry = P("Larry",M,1920,[may;joe;paul])

let sexToString = function
    |M -> "Male"
    |F -> "Female"

let formatter (P(n,s,yob,c)) = "name: " + n + " sex: " + (sexToString s) + " yearofbirth: " + (sprintf "%i" yob) + " names of children:" + (List.foldBack (fun (P(cn,_,_,_)) list -> " " + cn + list) c "")
let findAux p tree =
        let rec findInner t =
            match t with
            | P(n,_,_,_) when p(n) -> Some(t)
            | P(_,_,_,children) -> children |>  List.choose (findInner)
                                            |>  List.tryFind(fun _ -> true)
            | P(_,_,_,[]) -> None
        findInner tree

let find n t =
    let optionToString g =
        match g with
        | Some(p) -> formatter p
        | None    -> failwith "No such person"
    findAux (fun k -> k = n) t
    |> optionToString


let test34 = find "Joe" larry