Using list while mapping it in in Elixir

I am new to Elixir programming, so i tried to solve some problems from Project Euler, but have a problem with 7th problem.

I solved the task but the code below is too slow.

Stream.iterate(2, &(&1 + 1))
|> Stream.filter(fn x -> Stream.find(2..x, fn y -> rem(x, y) == 0 end) == nil end)
|> Enum.take(10_001)

I want to read the current list while processing, because it's 10 times faster!

In imperative programming languages like Rust, I can do this:

    let mut list = vec![2];
    let mut i = 2;
    let mut is_prime: bool;

    while list.len() != n {
        i += 1;
        is_prime = true;

        for j in &list {
            if i % j == 0 {
                is_prime = false;
                break;
            }
        }

        if is_prime {
            list.push(i);
        }
    }

When i tried to solve 10th problem, i wrote this code:

list = []

for i <- 2..(2_000_000 - 1) do
  if Enum.find(list, fn x -> rem(x, i) == 0 end) == nil do
    list = list ++ [i]
  end
end

Enum.sum(list) |> IO.puts()

But i got this message:

warning: variable "list" is unused (there is a variable with the same name in the context, use the pin operator (^) to match on it or prefix this variable with underscore if it is not meant to be used)

I expected the list to be updated but I can't even access it.

How can I solve these problems with my method in Elixir?

The following should do what you want (might take time to complete for big n values though since it's a quadratic algorithm):

Enum.reduce(2..n, [], fn i, acc -> 
  if Enum.any?(acc, fn x -> rem(i, x) == 0 end) do
    acc
  else
    [i | acc]
  end
end) 
|> Enum.reverse()

The important points:

• Using Enum.reduce/3 which is convenient to build something while accessing it
• Prepending (O(1)) instead of appending (O(n)) to the accumulator, and reversing at the end