#light

open System
open Microsoft.FSharp.Math
   

printfn "Grundlegende Konstrukte"
printfn "---------------------------"

let x = 2.2
let (y :float) = (float 3)
let z = x + y
printfn "%f + %f = %f" x y z



printfn "\n\nRekursion"
printfn "---------------------------"

let rec factorial n = if n=0 then 1 else n * factorial (n-1)

printfn "Fakultät von %i: %i" 4 (factorial 4)



printfn "\n\nCurrying"
printfn "---------------------------"

let add x y = x + y
let increment x = add x 1

let var = 2
printfn "Ausgangswert: %i" var
let var2 = increment var
printfn "Inkrementiert: %i" var2



printfn "\n\nPipelining"
printfn "---------------------------"

let square (x :int) = x * x
let negate x = -x

let complexFunction x = x |> square |> add 5 |> negate

printfn "%i" (complexFunction 10)


printfn "\n\nPattern Matching"
printfn "---------------------------"

let rec factorial2 (n :int64) = 
    match n with
    | 0L -> 1L
    | _ -> n * factorial2 (n - (int64 1))
    
printfn "Fakultät von %i: %i" 20 (factorial2 20L)


let rec factorial3 = function
    | 0 -> 1
    | n -> n * factorial3 (n - 1)

printfn "Fakultät von %i: %i" 5 (factorial3 5)

let rec factorial4 = function
    | 0 -> 1
    | n when n < 0 -> 0 //raise(new Exception("Number cannot be negative!"))
    | n when n > 0 -> n * factorial4 (n - 1)
    | _ -> 0
    
printfn "Fakultät von %i: %i" 5 (factorial3 5)
printfn "Fakultät von %i: %i" -5 (factorial4 -5)



printfn "\n\nClasses"
printfn "---------------------------"

type BankAccount = class
    val owner : string
    val mutable balance : int
    
    new (owner, balance) =
        {   owner = owner
            balance = balance }            
    
    member x.Deposit(value) = x.balance <- x.balance + value
    member x.Withdraw(value) = x.balance <- x.balance - value
end


let homer = new BankAccount("Homer", 100)
let marge = new BankAccount("Marge", 100)

let transfer amount (source : BankAccount) (target : BankAccount) =
    source.Withdraw(amount)
    target.Deposit(amount)
    printfn "Transferring %i EUR from %s to %s" amount source.owner target.owner

let printAccount (x : BankAccount) =
    printfn "%s has now %i EUR" x.owner x.balance
    
let printAccounts () =
    [homer; marge] |> Seq.iter printAccount
    
printAccounts()
transfer 50 homer marge
printAccounts()
transfer 30 marge homer
printAccounts()




Console.ReadKey()