Initial data commit

Task/Cantor-set/JavaScript/cantor-set-2.js

@@ -0,0 +1,72 @@
+(() => {
+    "use strict";
+
+    // ----------------- CANTOR STRINGS ------------------
+
+    // cantor :: [String] -> [String]
+    const cantor = xs => {
+        const go = s => {
+            const
+                m = Math.floor(s.length / 3),
+                blocks = take(m)(s);
+
+            return "█" === s[0] ? (
+                [blocks, " ".repeat(m), blocks]
+            ) : [s];
+        };
+
+        return xs.flatMap(go);
+    };
+
+    // ---------------------- TEST -----------------------
+    const main = () =>
+        showCantor(5);
+
+
+    // --------------------- DISPLAY ---------------------
+    // showCantor :: Int -> String
+    const showCantor = n =>
+        take(n)(
+            iterate(cantor)([
+                "█".repeat(3 ** (n - 1))
+            ])
+        )
+        .map(x => x.join(""))
+        .join("\n");
+
+
+    // ---------------- GENERIC FUNCTIONS ----------------
+
+    // iterate :: (a -> a) -> a -> Gen [a]
+    const iterate = f =>
+        // An infinite list of repeated
+        // applications of f to x.
+        function* (x) {
+            let v = x;
+
+            while (true) {
+                yield v;
+                v = f(v);
+            }
+        };
+
+
+    // take :: Int -> [a] -> [a]
+    // take :: Int -> String -> String
+    const take = n =>
+        // The first n elements of a list,
+        // string of characters, or stream.
+        xs => "GeneratorFunction" !== xs
+        .constructor.constructor.name ? (
+            xs.slice(0, n)
+        ) : [].concat(...Array.from({
+            length: n
+        }, () => {
+            const x = xs.next();
+
+            return x.done ? [] : [x.value];
+        }));
+
+    // MAIN ---
+    return main();
+})();