//1+2 |> ignore
//let a = 4 * 6
//let raisePowerTwo x = x ** 2.0
//let y = raisePowerTwo 3.0
//let s = @"apple\n"
//let c : System.Char = 'X'
//let b = true
//printfn "%.3f" 5.0
//printfn "%A" "apple"
//let add a b = a + b
//let addFour = add 4
//
//addFour 7
//
//let add4 b = 4 + b
//
//let add2 (a, b) = a + b
//
//add2 (4,7)
//
//let halfway a b=
//    let dif = b - a
//    let mid = dif / 2
//    mid + a
//
//halfway 5 11
//halfway 11 5
//let halfway5 = halfway 5
//halfway5 11
//let defineMessage () =
//    let message = "Hello"
//    printfn "%s" message
//    let message = "Hi"
//    printfn "%s" message
//
//defineMessage ()
//
let mathsPuzzle () =
    printf "Enter the day of the month on which you were born: "
    let input = int ( System.Console.ReadLine() )
    let x = input * 4
    let x = x + 13
    let x = x * 25
    let x = x - 200
    printf " Enter number of the month you were born: "
    let input = int ( System.Console.ReadLine() )
    let x = x + input
    let x = x * 2
    let x = x - 40
    let x = x * 50
    printf " Enter the last two digits of the year of your birth:"
    let input = int ( System.Console.ReadLine() )
    let x = x + input
    let x = x - 10500
    printf "Date of birth (ddmmyy): %i" x

mathsPuzzle ()

let changeType () =
    let x = 1
    let x = "change me"
    let x = x + 1
    printf "%s" x

let rec fact x =
    if x = 0 then
        1
    else
        x * fact ( x - 1 )

fact 5

let rec fib n =
    match n with
    | 0 -> 0
    | 1 -> 1
    | x -> fib ( x - 1 ) + fib ( x - 2 )

fib 10

let add a b = a + b

let add2 = fun a b -> a + b

let add3 = fun a -> (fun b -> a + b)

let add4 = function a -> function b -> a + b

let f = function
        | x when x < 10 -> "less than 10"
        |_              -> "not less than 10"


let f2 = fun x ->
    match x with
    | x when x < 10 -> "less than 10"
    |_              -> "not less than 10"

let s = "one, " ^ "two, " ^ "three"
let date = System.DateTime.Now + new System.TimeSpan( 365, 0, 0, 0 )

let (+) a b = a - b

4 + 5

"apple" + "pie"

let (+*) a b = (a+b)*a*b

let x = 34 +* 3

let list1 = []
let list2 = 1 :: []
let list3 = 1 :: 2 :: []
let list4 = [1;2;3;4]
let list5 = [1; 2 ] @ [ 3; 4; 5; 6 ]

let rec print_elements list =
    match list with
    | [] -> ()
    | head :: tail ->
        printfn "%A" head
        print_elements tail

print_elements [1; 2; 3; 4]