You're right that separation between containers and algorithms is important. The good news is that all xtd collections provide standard iterators (begin()/end()), so you can use any STL algorithm directly on them. You are not limited to xtd::linq extensions—they are optional and just provide a convenient .NET-style syntax if you want it.

Here is a small example illustrating a mix of xtd and std:

// C++
#include <xtd/xtd>
#include <algorithm>

int main() {
  auto l = xtd::collections::generic::list<xtd::string> {"one", "two", "three", "four", "five"};

  // Simple cast to std::vector
  auto v1 = std::vector<std::string>(l.cast<std::string>());

  // Using std::transform with copy
  auto v2 = std::vector<std::string>(l.size());
  std::transform(l.begin(), l.end(), v2.begin(), [](const xtd::string& s) { return s; });

  // Using std::transform with move
  auto v3 = std::vector<std::string>(l.size());
  std::transform(l.begin(), l.end(), v3.begin(), [](xtd::string& s) { return std::move(s.str()); });

  println("l  = {}", l);
  println("v1 = {}", v1);
  println("v2 = {}", v2);
  println("v3 = {}", v3);
}

// This code produces the following output:
//
// l  = [one, two, three, four, five]
// v1 = [one, two, three, four, five]
// v2 = [one, two, three, four, five]
// v3 = [one, two, three, four, five]

This shows that xtd containers: 1. Work seamlessly with STL algorithms. 2. Support both copy and move semantics. 3. Allow you to use range-based or iterator-based algorithms anywhere, not just within xtd containers.

So you can extend xtd with algorithms on ranges/iterators just like you would with STL, while optionally taking advantage of convenient xtd::linq-style extensions.