open System

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// =================================

// C# light

// =================================

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type Person(name :string, birthday :DateTime) =

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    /// Full name

    member this.Name = name 

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    /// Birthday

    member this.Birthday = birthday

// =================================

// DTO Example    

// =================================

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// I have renamed Person!

type Person2 = {name :string; birthday :DateTime}

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let person = {name="Alice"; birthday=DateTime.Today}    

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​

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// =================================

// Automatically generate code for equality

// =================================

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let alice1 = {name="Alice"; birthday=DateTime.Today}

let alice2 = {name="Alice"; birthday=DateTime.Today}

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if alice1 = alice2 then

    Console.WriteLine("Alice1 and Alice2 are equal")  // true!

// =================================

// Immutability    

// =================================

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//define an immutable Alice 

let alice3 = {name="Alice"; birthday=DateTime.Today}

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//changing immutable Alice to Bob gives an error

// alice3 <- {name="Bob"; birthday=DateTime.Today}  // This value is not mutable

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//define a mutable Alice 

let mutable alice4 = {name="Alice"; birthday=DateTime.Today}

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//changing mutable Alice to Bob is ok

alice4 <- {name="Bob"; birthday=DateTime.Today}

Console.WriteLine("Alice's name is " + alice4.name)

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// =================================

// Non-null reference classes

// =================================

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// alice4 <- null  // error

                   // The type 'Person' does not have 'null' as a proper value

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// =================================

// Allow anonymous types to implement interfaces                   

// =================================

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do 

    // create it

    use tempDisposable = 

      {new IDisposable with 

        member this.Dispose() = Console.WriteLine("Disposed") }

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    // do something             

    Console.WriteLine("Doing something") 

    // tempDisposable goes out of scope and is disposed

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// =================================

// Allow subclasses to be merged into a single "case" class

// =================================

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type CheckNo = int

type CardType = Visa | Mastercard

type CardNo = string

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type PaymentMethod = 

| Cash

| Check of CheckNo

| Card of CardType * CardNo  

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let cash = Cash

let check = Check 123

let card = Card (Visa, "4012888888881881")

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let printPayment payment =   

   match payment with

   | Cash -> printfn "Cash"

   | Check checkNo -> printfn "Check %i" checkNo

   | Card (cardType,cardNo) -> printfn "Card %A %s" cardType cardNo

printPayment cash

printPayment check

printPayment card

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