Scala : rename files in sandbox

1 files changed, 56 insertions, 0 deletions

diff --git a/Scala/sandbox/2-curry.scala b/Scala/sandbox/2-curry.scala
new file mode 100644
index 0000000..adc7e75
--- /dev/null
+++ b/Scala/sandbox/2-curry.scala
@@ -0,0 +1,56 @@
+
+object Curry {
+
+  // high order function
+  def sum(f: Int => Int, a: Int, b: Int) = {
+    def loop(a: Int, acc: Int): Int  =
+      if (a > b) acc
+      else loop(a + 1, f(a) + acc)
+    loop(a, 0)
+  }
+
+  // curry version: this function return an (Int, Int) => Int function
+  def sumCurry(f: Int => Int): (Int, Int) => Int = {
+    def sumF(a: Int, b: Int): Int  =
+      if (a > b) 0
+      else f(a) + sumF(a + 1, b)
+    sumF
+  }
+
+  def cube (x: Int): Int = x * x * x
+
+  def sumInts   = sumCurry(x => x)
+  def sumCubes  = sumCurry(x => x * x * x)
+
+  // syntax shortcut
+  def sumCurryShort(f: Int => Int)(a: Int, b: Int): Int =
+    if (a > b) 0 else f(a) + sumCurryShort(f)(a + 1, b)
+
+  // add _ if you want to treat it as a partially applied function
+  def sumCubesShort  = sumCurryShort(cube)_
+
+  // product
+  def product(f: Int => Int)(a: Int, b: Int): Int =
+    if (a > b) 1 else f(a) * product(f)(a + 1, b)
+
+  def fact(n: Int) = product(x => x)(1, n)
+
+  // add unit value and combining function => sum and product generalisation
+  def mapReduce(f: Int => Int, c: (Int, Int) => Int, u: Int )(a: Int, b: Int): Int =
+    if (a > b) u else c(f(a), mapReduce(f, c, u)(a + 1, b))
+
+  def run = {
+    println("Curry")
+    println(sum(x => x * x, 3, 5))
+    println(sumInts(3, 5))
+    println(sumCurry(cube)(3, 5))
+    println(sumCubes(3, 5))
+    println(sumCurryShort(cube)(3, 5))
+    println(sumCubesShort(3, 5))
+    println(product(x => x * x)(3, 4))
+    println(fact(4))
+    println(mapReduce(x => x * x, (x, y)=> x + y, 0)(3, 5))
+    println(mapReduce(x => x * x, (x, y)=> x * y, 1)(3, 4))
+  }
+
+}