- Added guest contributions by Laurent Rosenfeld.

7 files changed, 79 insertions, 0 deletions

diff --git a/challenge-171/laurent-rosenfeld/d/ch-2.d b/challenge-171/laurent-rosenfeld/d/ch-2.d
new file mode 100644
index 0000000000..736b77ac0c
--- /dev/null
+++ b/challenge-171/laurent-rosenfeld/d/ch-2.d
@@ -0,0 +1,13 @@
+import std.stdio;
+
+T delegate(S) compose(T, U, S)(in T delegate(U) f,
+                               in U delegate(S) g) {
+    return s => f(g(s));
+}
+
+void main() {
+    auto h = compose((int x) => x / 2 + 1, (int x) => x * 2);
+    for (int i = 1; i <= 6; i++) {
+        writeln(i);
+    }
+}
diff --git a/challenge-171/laurent-rosenfeld/julia/ch-2.jl b/challenge-171/laurent-rosenfeld/julia/ch-2.jl
new file mode 100644
index 0000000000..0256eb8775
--- /dev/null
+++ b/challenge-171/laurent-rosenfeld/julia/ch-2.jl
@@ -0,0 +1,13 @@
+function f(p)
+    return p / 2 + 1
+end
+function g(p)
+    return p * 2
+end
+function compose(h1, h2)
+    return h1 ∘ h2;
+end
+h = compose(f, g)
+for i in 1:5
+    println(h(i), "  ", f(g(i)))
+end
diff --git a/challenge-171/laurent-rosenfeld/kotlin/ch-2.kt b/challenge-171/laurent-rosenfeld/kotlin/ch-2.kt
new file mode 100644
index 0000000000..e16161e7e6
--- /dev/null
+++ b/challenge-171/laurent-rosenfeld/kotlin/ch-2.kt
@@ -0,0 +1,11 @@
+fun f(x: Int): Int = x/2 + 1
+
+fun g(x: Int): Int = x * 2
+
+fun compose(f: (Int) -> Int,  g: (Int) -> Int): (Int) -> Int  = { f(g(it)) }
+
+fun main() {
+    for (i in 2..6) {
+        println(compose(::f, ::g)(i))
+    }
+}
diff --git a/challenge-171/laurent-rosenfeld/nim/ch-2.nim b/challenge-171/laurent-rosenfeld/nim/ch-2.nim
new file mode 100644
index 0000000000..20cd66664a
--- /dev/null
+++ b/challenge-171/laurent-rosenfeld/nim/ch-2.nim
@@ -0,0 +1,10 @@
+import sugar
+
+proc compose[A,B,C](h1: A -> B, h2: B -> C): A -> C = (x: A) => h1(h2(x))
+
+proc f(x: int): int = int(x / 2) + 1
+proc g(x: int): int = x * 2
+
+var h = compose(f, g)
+for i in 1..6:
+  echo (h(i), f(g(i)))
diff --git a/challenge-171/laurent-rosenfeld/python/ch-2.py b/challenge-171/laurent-rosenfeld/python/ch-2.py
new file mode 100644
index 0000000000..01cb4943d5
--- /dev/null
+++ b/challenge-171/laurent-rosenfeld/python/ch-2.py
@@ -0,0 +1,11 @@
+def compose(f1, f2):
+    return lambda x: f1(f2(x))
+def f(p):
+    return p / 2 + 1
+def g(p):
+    return p * 2
+
+h = compose(f, g)
+
+for i in range(1, 6):
+    print (f(g(i)), " ", h(i))
diff --git a/challenge-171/laurent-rosenfeld/ruby/ch-2.rb b/challenge-171/laurent-rosenfeld/ruby/ch-2.rb
new file mode 100644
index 0000000000..167cf47cdd
--- /dev/null
+++ b/challenge-171/laurent-rosenfeld/ruby/ch-2.rb
@@ -0,0 +1,10 @@
+def compose(h1, h2)
+    lambda {|x| h1.call(h2.call(x))}
+end
+f = lambda { |x| return x / 2 + 1 }
+g = lambda { |x| return x * 2 }
+
+h = compose(f, g)
+for i in 1.upto(6)
+    print ("#{h[i]}  #{f.call(g.call(i))}\n")
+end
diff --git a/challenge-171/laurent-rosenfeld/scala/ch-2.scala b/challenge-171/laurent-rosenfeld/scala/ch-2.scala
new file mode 100644
index 0000000000..358b93ee4f
--- /dev/null
+++ b/challenge-171/laurent-rosenfeld/scala/ch-2.scala
@@ -0,0 +1,11 @@
+object first_class extends App {
+  def compose[A](h1: A => A, h2: A => A) = { x: A => h1(h2(x)) }
+
+  def f(x: Int) = x / 2 + 1
+  def g(x: Int) = x * 2
+
+  val h = compose(f, g)
+  for (i <- 1 to 6) {
+    println(s"${h(i)}  ${f(g(i))}")
+  }
+}