Add tasks for all the new languages

Task/First-class-functions/Sidef/first-class-functions.sidef

@@ -0,0 +1,15 @@
+func compose(f,g) {
+    func (*args) {
+        f(g(args...));
+    }
+}
+
+var cube  = func(a) { a.pow(3) };
+var croot = func(a) { a.root(3) };
+
+var flist1 = [Math.method(:sin), Math.method(:cos), cube];
+var flist2 = [Math.method(:asin), Math.method(:acos), croot];
+
+flist1.range.each { |i|
+    say compose(flist1[i], flist2[i])(0.5);
+}