某所のアレをやってみた

gifts.fs

type Family = Blair | Smith | Kelly | Tavares | Chen | Singh
type Person = { First: string; Last: Family }

let blair's first = { First = first; Last = Blair }
let smith's first = { First = first; Last = Smith }
let kelly's first = { First = first; Last = Kelly }
let tavares' first = { First = first; Last = Tavares }
let chen's first = { First = first; Last = Chen }
let singh's first = { First = first; Last = Singh }

let gift person giftee =
    if person.Last = giftee.Last then None
    else Some(person.First, giftee.First)

let giftAll ns =
    let rec giftAllrec ns result =
        match ns with
        | name::rest ->
            let newResult =
                List.map (gift name) rest
                |> List.append result
            giftAllrec rest newResult
        | _ -> result
    giftAllrec ns []

let names = [
    blair's "Toby"
    smith's "Ian"
    kelly's "Martin"
    kelly's "Kate"
    smith's "John"
    tavares' "Bruno"
    chen's "Vicky"
    kelly's "Sarah"
    kelly's "Mark"
    singh's "Ajay"
]

giftAll names
|> List.choose id
|> List.iter (fun (name, giftee) ->
    printfn "%s -> %s" name giftee
    printfn "%s -> %s" giftee name
)


(*
Result
-------------
Toby -> Ian
Ian -> Toby
Toby -> Martin
Martin -> Toby
Toby -> Kate
Kate -> Toby
Toby -> John
John -> Toby
Toby -> Bruno
Bruno -> Toby
Toby -> Vicky
Vicky -> Toby
Toby -> Sarah
Sarah -> Toby
Toby -> Mark
Mark -> Toby
Toby -> Ajay
Ajay -> Toby
Ian -> Martin
Martin -> Ian
Ian -> Kate
Kate -> Ian
Ian -> Bruno
Bruno -> Ian
Ian -> Vicky
Vicky -> Ian
Ian -> Sarah
Sarah -> Ian
Ian -> Mark
Mark -> Ian
Ian -> Ajay
Ajay -> Ian
Martin -> John
John -> Martin
Martin -> Bruno
Bruno -> Martin
Martin -> Vicky
Vicky -> Martin
Martin -> Ajay
Ajay -> Martin
Kate -> John
John -> Kate
Kate -> Bruno
Bruno -> Kate
Kate -> Vicky
Vicky -> Kate
Kate -> Ajay
Ajay -> Kate
John -> Bruno
Bruno -> John
John -> Vicky
Vicky -> John
John -> Sarah
Sarah -> John
John -> Mark
Mark -> John
John -> Ajay
Ajay -> John
Bruno -> Vicky
Vicky -> Bruno
Bruno -> Sarah
Sarah -> Bruno
Bruno -> Mark
Mark -> Bruno
Bruno -> Ajay
Ajay -> Bruno
Vicky -> Sarah
Sarah -> Vicky
Vicky -> Mark
Mark -> Vicky
Vicky -> Ajay
Ajay -> Vicky
Sarah -> Ajay
Ajay -> Sarah
Mark -> Ajay
Ajay -> Mark
*)