What is the use of assert in the following program creating a linked list? Isn't it useless?-CodePudding

bool isTree(List<Object> tree) {
  if ((tree is! List) | (tree.length < 1)) {
    return false;
  }
  for (final branch in branches(tree)) {
    if (!isTree(branch)) {
      return false;
    }
  }
  return true;
}

List branches(List tree) {
  return tree.sublist(1);
}

Object label(List tree) {
  return tree[0];
}

List tree(rootLabel, [List branches = const []]) {
  for (final branch in branches) {
    assert(isTree(branch));
  }
  return ([rootLabel]   branches);
}

bool isLeaf(List tree) {
  return branches(tree).isEmpty;
}

var t = tree('hey', [
  tree('hello'),
  tree('hum', [tree('there'), tree('hey')])
]);

If i were to remove the for loop with the assert function, and also the is_tree function, the program still returns the same results as with them, So aren't they useless?



List branches(List tree) {
  return tree.sublist(1);
}

Object label(List tree) {
  return tree[0];
}

List tree(rootLabel, [List branches = const []]) {
  
  return ([rootLabel]   branches);
}

bool isLeaf(List tree) {
  return branches(tree).isEmpty;
}

var t = tree('hey', [
  tree('hello'),
  tree('hum', [tree('there'), tree('hey')])
]);

Here is the full tutorial when i am learning this https://composingprograms.com/pages/23-sequences.html#trees

CodePudding user response：

It's there to make sure all branches are trees. Without the assert you are able to write this without any errors.

var t = tree('hey', ['notATree']);

With the assert it will throw an error.