Add tasks for all the new languages

Task/Polymorphic-copy/EchoLisp/polymorphic-copy.echolisp

@@ -0,0 +1,24 @@
+(lib 'types)
+(lib 'struct)
+
+(struct T (integer:x)) ;; super class
+(struct S T (integer:y)) ;; sub class
+(struct K (T:box)) ;; container class, box must be of type T, or derived
+
+(define k-source (K (S 33 42)))
+(define k-copy (copy k-source))
+
+k-source
+    → #<K> (#<S> (33 42)) ;; new container, with a S in box
+k-copy
+    → #<K> (#<S> (33 42)) ;; copied S type
+
+(set-S-y! (K-box k-source) 666) ;; modify k-source.box.y
+
+k-source
+    → #<K> (#<S> (33 666)) ;; modified
+k-copy
+    → #<K> (#<S> (33 42))  ;; unmodified
+
+(K "string-inside") ;; trying to put a string in the container box
+😡 error: T : type-check failure : string-inside → 'K:box'

Task/Polymorphic-copy/Nim/polymorphic-copy.nim

@@ -0,0 +1,37 @@
+type
+  T = ref object of TObject
+    myValue: string
+  S1 = ref object of T
+  S2 = ref object of T
+
+method speak(x: T)  = echo "T Hello ", x.myValue
+method speak(x: S1) = echo "S1 Meow ", x.myValue
+method speak(x: S2) = echo "S2 Woof ", x.myValue
+
+echo "creating initial objects of types S1, S2, and T"
+var a = S1(myValue: "Green")
+a.speak
+var b = S2(myValue: "Blue")
+b.speak
+var u = T(myValue: "Blue")
+u.speak
+
+echo "Making copy of a as u, colors and types should match"
+u.deepCopy(a)
+u.speak
+a.speak
+
+echo "Assigning new color to u, A's color should be unchanged."
+u.myValue = "Orange"
+u.speak
+a.speak
+
+echo "Assigning u to reference same object as b, colors and types should match"
+u = b
+u.speak
+b.speak
+
+echo "Assigning new color to u. Since u,b references same object b's color changes as well"
+u.myValue = "Yellow"
+u.speak
+b.speak

Task/Polymorphic-copy/Sidef/polymorphic-copy.sidef

@@ -0,0 +1,22 @@
+class T(value) {
+    method display {
+        say value;
+    }
+}
+
+class S(value) < T {
+    method display {
+        say value;
+    }
+}
+
+var obj1 = T("T");
+var obj2 = S("S");
+var obj3 = obj2.dclone;         # make a deep clone of obj2
+
+obj1.value = "foo";             # change the value of obj1
+obj2.value = "bar";             # change the value of obj2
+
+obj1.display;                   # prints "foo"
+obj2.display;                   # prints "bar"
+obj3.display;                   # prints "S"

Task/Polymorphic-copy/Swift/polymorphic-copy.swift

@@ -0,0 +1,24 @@
+class T {
+  required init() { } // constructor used in polymorphic initialization must be "required"
+  func identify() {
+    println("I am a genuine T")
+  }
+  func copy() -> T {
+    let newObj : T = self.dynamicType() // call an appropriate constructor here
+    // then copy data into newObj as appropriate here
+    // make sure to use "self.dynamicType(...)" and
+    // not "T(...)" to make it polymorphic
+    return newObj
+  }
+}
+
+class S : T {
+  override func identify()  {
+    println("I am an S")
+  }
+}
+
+let original : T = S()
+let another : T = original.copy()
+println(original === another) // prints "false" (i.e. they are different objects)
+another.identify() // prints "I am an S"