September Morn Update

Task/Flatten-a-list/JavaScript/flatten-a-list-5.js

@@ -1,2 +1,2 @@
-// flatten :: Tree a -> [a]
-const flatten = t => Array.isArray(t) ? [].concat(...t.map(flatten)) : t;
+// flatten :: NestedList a -> [a]
+const flatten = nest => nest.flat(Infinity);

Task/Flatten-a-list/JavaScript/flatten-a-list-6.js

@@ -1,12 +1,5 @@
-function flatten(list) {
-  for (let i = 0; i < list.length; i++) {
-    while (true) {
-      if (Array.isArray(list[i])) {
-      	list.splice(i, 1, ...list[i]);
-      } else {
-      	break;
-      }
-    }
-  }
-  return list;
-}
+// flatten :: Nested List a -> [a]
+const flatten = t => {
+    const go = x => Array.isArray(x) ? x.flatMap(go) : x
+    return go(t);
+};

Task/Flatten-a-list/JavaScript/flatten-a-list-7.js

@@ -0,0 +1,12 @@
+function flatten(list) {
+  for (let i = 0; i < list.length; i++) {
+    while (true) {
+      if (Array.isArray(list[i])) {
+      	list.splice(i, 1, ...list[i]);
+      } else {
+      	break;
+      }
+    }
+  }
+  return list;
+}

Task/Flatten-a-list/JavaScript/flatten-a-list-8.js

@@ -0,0 +1,8 @@
+// flatten :: Nested List a -> a
+const flatten = t => {
+    let xs = t;
+    while (xs.some(Array.isArray)) (
+        xs = [].concat(...xs)
+    )
+    return xs;
+};