558445a88826e1376b000011

src/5440f068cf362592e4000cd6.js

@@ -0,0 +1,25 @@
+
+const sequence = fn => {
+  return {
+    take: n => {
+      const res = [];
+      for (let i = 0; i < n; ++i) {
+        res[i] = fn(i);
+      }
+      return res;
+    },
+    takeWhile: pred => {
+      const res = [];
+      for (let i = 0; 1; ++i) {
+        const val = fn(i);
+        if (!pred(val)) break;
+        res[i] = fn(i);
+      }
+      return res;
+    },
+  };
+};
+
+
+sequence(n => n).takeWhile(n => n < 10); // [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
+sequence(n => n * n).take(10); // [0, 1, 4, 9, 16, 25, 36, 49, 64, 81]