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'