FPIS - Chapter 1.ipynb

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            "source": "// A coffee example\n\ndef c1_1_2() {\n    case class CreditCard(id: String)\n    \n    case class Charge(cc: CreditCard, amount: Double) {\n        def combine(other: Charge): Charge = \n            if (cc == other.cc) Charge(cc, amount + other. amount)\n            else throw new Exception(\"Can't combine charges to different cards\")\n        \n        def doCharge() {\n            println(s\"\"\"Charge $amount dollars to credit card \"${cc.id}\".\"\"\")\n        }\n    }\n    \n    case class Coffee(price: Int)\n    \n    class Cafe {\n        def buyCoffee(cc: CreditCard): (Coffee, Charge) = {\n            val cup = new Coffee(10)\n            (cup, Charge(cc, cup.price))\n        }\n        \n        def buyCoffees(cc: CreditCard, n: Int): (List[Coffee], Charge) = {\n            var purchars: List[(Coffee, Charge)] = List.fill(n)(buyCoffee(cc))\n            val (coffees, charges) = purchars.unzip\n            (coffees, charges.reduce((c1, c2) => c1.combine(c2)))\n        }\n        \n        def coalesce(charges: List[Charge]): List[Charge] = {\n            charges.groupBy(_.cc).values.map(_.reduce(_ combine _)).toList\n        }\n    }\n    \n    val cafe = new Cafe()\n    val aliceCreditCard = CreditCard(\"Alice\")\n    val bobCreditCard = CreditCard(\"Bob\")\n    val (_, firstCharge) = cafe.buyCoffees(aliceCreditCard, 10)\n    val (_, secondCharge) = cafe.buyCoffees(bobCreditCard, 20)\n    val (_, thirdCharge) = cafe.buyCoffees(aliceCreditCard, 30)\n    val combinedCharges = cafe.coalesce(List(firstCharge, secondCharge, thirdCharge))\n    println(combinedCharges)\n    \n    combinedCharges.foreach(_.doCharge)\n}\n\nc1_1_2()", 
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                    "text": "List(Charge(CreditCard(Bob),200.0), Charge(CreditCard(Alice),400.0))\nCharge 200.0 dollars to credit card \"Bob\".\nCharge 400.0 dollars to credit card \"Alice\".\n", 
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