const node = getNode(id)(tree);
const children = node ? node.children :
id === TREE_ROOT_ID
- ? getRootNodeChildren(tree)
+ ? getRootNodeChildrenIds(tree)
: [];
return children
const mapNodeValue = <T, R>(mapFn: (value: T) => R) => (node: TreeNode<T>): TreeNode<R> =>
({ ...node, value: mapFn(node.value) });
-const getRootNodeChildren = <T>(tree: Tree<T>) =>
+const getRootNodeChildrenIds = <T>(tree: Tree<T>) =>
Object
.keys(tree)
.filter(id => getNode(id)(tree)!.parent === TREE_ROOT_ID);
+
const addChild = (parentId: string, childId: string) => <T>(tree: Tree<T>): Tree<T> => {
const node = getNode(parentId)(tree);
if (node) {