F# Car Solitaire

module CarSolitaire
open System
type Card = {Value:string; Suit:string}

let main() =
    let mutable start = 0
    Console.Write("Welcome to Car Solitaire!\n")
    while (start = 0) do
        Console.Write("Please enter a command. (Hit C to display commands) ")
        let str = Console.ReadLine()
        let upper = str.ToUpper()

        if (upper.Length > 1) then
            Console.Write("Invalid command length: {0}. ", upper.Length)

        let array = upper.ToCharArray()
        let array2 = Array.sub array 0 1
        let command = new string(array2)

        if (command = "C") then
            Console.Write("X: Exit game.\t\t\t\tL: Display leaderboard.\nD: Display current deck.\t\tC: Display commands.\n")
            Console.Write("P: Play game while watching.\t\tH: Play hidden game (game finishes without user input).\n\n")
        elif (command = "X") then
            Console.Write("Exiting. Goodbye!\n")
            Environment.Exit 1
        elif (command = "L") then
            Console.Write("Leaderboard stuff goes here")
        elif (command = "D") then
            Console.Write("No game has been started.")
        elif (command = "P" || command = "H") then
            start <- 1
        else
            Console.Write("Invalid command. ")

    let values = [| "A"; "2"; "3"; "4"; "5"; "6"; "7"; "8"; "9"; "10"; "J"; "Q"; "K" |]
    let suits = [| "Hearts"; "Spades"; "Clubs"; "Diamonds" |]
    let deck = Array.empty<Card>

    for h in 0..51 do
        for i in 0..values.Length do
            for j in 0..suits.Length do
                let insert = Card [values.[i]; suits.[j]]
                deck.[0] <- insert