edx-module2.fs

open System

let rec queryForNonNegativeInt msg =
    printf msg
    let parsed, number = Int32.TryParse(Console.ReadLine());
    if parsed then 
        if number < 0 then queryForNonNegativeInt msg
        else number
    else queryForNonNegativeInt msg

let queryForNumberOfPeople () =
    queryForNonNegativeInt "number of people: "

let queryForName () =
    printf "name: "
    Console.ReadLine()

let queryForAge () = 
    queryForNonNegativeInt "age: "

let queryForPerson num =
    printfn "person #%A" (num + 1)
    let name = queryForName()
    let age = queryForAge()
    (name, age)

let queryForPeoples numberOfPeople = 
    let rec queryForPeoples num acc = 
        if num = numberOfPeople then acc
        else queryForPerson num :: queryForPeoples (num+1) acc
    queryForPeoples 0 []

let verdict person =
    let name, age = person
    if age >= 20 then
        name + " is no longer a teenager"
    elif age > 13 then
        name + " is a teenager"
    else
        name + " is a child"

[<EntryPoint>]
let main argv = 
    let num = queryForNumberOfPeople()
    let xs = queryForPeoples num    

    xs |> List.map verdict |> List.iter (printfn "%s") |> ignore
    
    Console.ReadLine() |> ignore
    0