Munchausen numbers: Difference between revisions

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@@ Line 896: / Line 896: @@
 Or, composing reusable primitives:
-<lang JavaScript>(function () {
+<lang JavaScript>(() => {
     'use strict';
+    const main = () =>
+        filter(isMunchausen, enumFromTo(1, 5000));
     // isMunchausen :: Int -> Bool
-    let isMunchausen = n =>
+    const isMunchausen = n =>
-            !isNaN(n) && (
+        !isNaN(n) && (
-                n.toString()
+            n.toString()
-                .split('')
+            .split('')
-                .reduce((a, c) => {
+            .reduce((a, c) => {
-                    let d = parseInt(c, 10);
+                let d = parseInt(c, 10);
-                    return a + Math.pow(d, d);
-                }, 0) === n
-            ),
+                return a + Math.pow(d, d);
-        // range(intFrom, intTo, intStep?)
-        // Int -> Int -> Maybe Int -> [Int]
+            }, 0) === n
-        range = (m, n, step) => {
+        );
-            let d = (step || 1) * (n >= m ? 1 : -1);
+    // GENERIC ---------------------------
-            return Array.from({
-                length: Math.floor((n - m) / d) + 1
-            }, (_, i) => m + (i * d));
-        };
+    // enumFromTo :: Int -> Int -> [Int]
+    const enumFromTo = (m, n) =>
+        Array.from({
+            length: 1 + n - m
+        }, (_, i) => m + i);
+    // filter :: (a -> Bool) -> [a] -> [a]
-    return range(1, 5000)
-        .filter(isMunchausen);
+    const filter = (f, xs) => xs.filter(f);
-})();</lang>
+    // MAIN ---
+    return main();
+})();</lang>
 {{Out}}
 <lang JavaScript>[1, 3435]</lang>