2016 Update

Task/Averages-Median/JavaScript/averages-median-2.js

@@ -0,0 +1,52 @@
+(() => {
+    'use strict';
+
+    // median :: [Num] -> Num
+    function median(xs) {
+        // nth :: [Num] -> Int -> Maybe Num
+        let nth = (xxs, n) => {
+                if (xxs.length > 0) {
+                    let [x, xs] = uncons(xxs),
+                        [ys, zs] = partition(y => y < x, xs),
+                        k = ys.length;
+
+                    return k === n ? x : (
+                        k > n ? nth(ys, n) : nth(zs, n - k - 1)
+                    );
+                } else return undefined;
+            },
+            n = xs.length;
+
+        return even(n) ? (
+            (nth(xs, div(n, 2)) + nth(xs, div(n, 2) - 1)) / 2
+        ) : nth(xs, div(n, 2));
+    }
+
+
+
+    // GENERIC
+
+    // partition :: (a -> Bool) -> [a] -> ([a], [a])
+    let partition = (p, xs) =>
+        xs.reduce((a, x) =>
+            p(x) ? [a[0].concat(x), a[1]] : [a[0], a[1].concat(x)], [
+                [],
+                []
+            ]),
+
+        // uncons :: [a] -> Maybe (a, [a])
+        uncons = xs => xs.length ? [xs[0], xs.slice(1)] : undefined,
+
+        // even :: Integral a => a -> Bool
+        even = n => n % 2 === 0,
+
+        // div :: Num -> Num -> Int
+        div = (x, y) => Math.floor(x / y);
+
+    return [
+        [],
+        [5, 3, 4],
+        [5, 4, 2, 3],
+        [3, 4, 1, -8.4, 7.2, 4, 1, 1.2]
+    ].map(median);
+})();

Task/Averages-Median/JavaScript/averages-median-3.js

@@ -0,0 +1,6 @@
+[
+  null,
+  4,
+  3.5,
+  2.1
+]