Data commit

Task/Function-composition/JavaScript/function-composition-7.js

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+(() => {
+    "use strict";
+
+    // -------------- MULTIPLE COMPOSITION ---------------
+
+    // compose (<<<) :: (b -> c) -> (a -> b) -> a -> c
+    const compose = (...fs) =>
+        // A function defined by the right-to-left
+        // composition of all the functions in fs.
+        fs.reduce(
+            (f, g) => x => f(g(x)),
+            x => x
+        );
+
+    // ---------------------- TEST -----------------------
+    const
+        sqrt = Math.sqrt,
+        succ = x => x + 1,
+        half = x => x / 2;
+
+    return compose(half, succ, sqrt)(5);
+
+    // --> 1.618033988749895
+})();