2016 Update

Task/Function-composition/JavaScript/function-composition-3.js

@@ -0,0 +1,49 @@
+(function () {
+    'use strict';
+
+
+    // iterativeComposed :: [f] -> f
+    function iterativeComposed(fs) {
+
+        return function (x) {
+            var i = fs.length,
+                e = x;
+
+            while (i--) e = fs[i](e);
+            return e;
+        }
+    }
+
+    // foldComposed :: [f] -> f
+    function foldComposed(fs) {
+
+        return function (x) {
+            return fs
+                .reduceRight(function (a, f) {
+                    return f(a);
+                }, x);
+        };
+    }
+
+
+    var sqrt = Math.sqrt,
+
+        succ = function (x) {
+            return x + 1;
+        },
+
+        half = function (x) {
+            return x / 2;
+        };
+
+
+    // Testing two different multiple composition ([f] -> f) functions
+
+    return [iterativeComposed, foldComposed]
+        .map(function (compose) {
+
+            // both functions compose from right to left
+            return compose([half, succ, sqrt])(5);
+
+        });
+})();

Task/Function-composition/JavaScript/function-composition-4.js

@@ -0,0 +1,21 @@
+(() => {
+    'use strict';
+
+
+    // compose :: [(a -> a)] -> (a -> a)
+    let compose = fs => x => fs.reduceRight((a, f) => f(a), x);
+
+
+    // TEST a composition of 3 functions (right to left)
+
+    let sqrt = Math.sqrt,
+
+        succ = x => x + 1,
+
+        half = x => x / 2;
+
+
+    return compose([half, succ, sqrt])(5);
+
+    // --> 1.618033988749895
+})();