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+++ b/Fahad/Scala/Chapter5.sc Sat Oct 25 17:28:56 2014 +0100
@@ -0,0 +1,55 @@
+package greeter
+
+object Chapter5 {
+ println("Welcome to the Scala worksheet") //> Welcome to the Scala worksheet
+
+ /////////////////////////////////////////////////////////////////////////////
+ // CHAPTER 5: FIRST-CLASS FUNCTIONS
+
+ /*
+ // Write a function to sumall integers between two given numbers a and b
+ def sumInts(a: Int, b: Int): Int =
+ if (a > b) 0 else a + sumInts(a + 1, b)
+
+ sumInts(1, 5)
+
+ //Write a function to sum the squares of all integers between two given numbers a and b
+ def square(x: Int): Int = x * x
+ def sumSquares(a: Int, b: Int): Int =
+ if (a > b) 0 else square(a) + sumSquares(a + 1, b)
+
+ square(5)
+
+ //Write a function to sum the powers 2n of all integers n between two given numbers a and b:
+ def powerOfTwo(x: Int): Int = if (x == 0) 1 else 2 * powerOfTwo(x - 1)
+ def sumPowersOfTwo(a: Int, b: Int): Int =
+ if (a > b) 0 else powerOfTwo(a) + sumPowersOfTwo(a + 1, b)
+
+ sumPowersOfTwo(2, 4)
+ */
+
+ def sum(f: Int => Int, a: Int, b: Int): Int =
+ if (a > b) 0 else f(a) + sum(f, a + 1, b) //> sum: (f: Int => Int, a: Int, b: Int)Int
+
+ //def sumInts(a: Int, b: Int): Int = sum(id, a, b)
+ //def sumInts(a: Int, b: Int): Int = sum((x: Int) => x, a, b)
+ def sumInts(a: Int, b: Int): Int = sum(x => x, a, b)
+ //> sumInts: (a: Int, b: Int)Int
+ //def sumSquares(a: Int, b: Int): Int = sum(square, a, b)
+ //def sumSquares(a: Int, b: Int): Int = sum((x: Int) => x * x, a, b)
+ def sumSquares(a: Int, b: Int): Int = sum(x => x * x, a, b)
+ //> sumSquares: (a: Int, b: Int)Int
+ def sumPowersOfTwo(a: Int, b: Int): Int = sum(powerOfTwo, a, b)
+ //> sumPowersOfTwo: (a: Int, b: Int)Int
+
+ def id(x: Int): Int = x //> id: (x: Int)Int
+ def square(x: Int): Int = x * x //> square: (x: Int)Int
+ def powerOfTwo(x: Int): Int = if (x == 0) 1 else 2 * powerOfTwo(x - 1)
+ //> powerOfTwo: (x: Int)Int
+
+ // 5.2: Currying
+
+
+
+
+}
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