September 2017 Update

Task/Binary-digits/JavaScript/binary-digits-2.js

@@ -1,7 +1,30 @@
-console.log(
+(() => {
 
-    [5, 50, 9000].map(function (n) {
-        return (n).toString(2);
-    }).join('\n')
+    // showIntAtBase_ :: // Int -> Int -> String
+    const showIntAtBase_ = (base, n) => (n)
+        .toString(base);
 
-)
+    // showBin :: Int -> String
+    const showBin = n => showIntAtBase_(2, n);
+
+    // GENERIC FUNCTIONS FOR TEST ---------------------------------------------
+
+    // intercalate :: String -> [a] -> String
+    const intercalate = (s, xs) => xs.join(s);
+
+    // map :: (a -> b) -> [a] -> [b]
+    const map = (f, xs) => xs.map(f);
+
+    // unlines :: [String] -> String
+    const unlines = xs => xs.join('\n');
+
+    // show :: a -> String
+    const show = x => JSON.stringify(x);
+
+    // TEST -------------------------------------------------------------------
+
+    return unlines(map(
+        n => intercalate(' -> ', [show(n), showBin(n)]),
+        [5, 50, 9000]
+    ));
+})();