Reusing compile time code

Questions & Help Questions
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16

Sorry, you are right.
It is absolutely not needed, you can get away with it by storing the value at compile time in an attribute and invoke it inside a function.

Something like this based on Michal’s code.

defmodule SportsCsvReader do
  @sports_data         :my_app
    |> :code.priv_dir()
    |> Path.join("awesome_csv.csv")
    |> File.stream!()
    |> CSV.decode!(headers: false, separator: ?;)
    |> Stream.map(&List.to_tuple/1)
    |> Stream.uniq()
    |> Enum.map(fn {sport, country, league} ->
      {String.trim(sport), String.trim(country), String.trim(league)}
    end)

  def sports_data(), do: @sports_data

  def extract_sports(sports_data) do
    sports_data
    |> Enum.map(fn {sport, _country, _league} -> sport end)
    |> Enum.filter(fn sport -> sport != "" end)
  end

  def extract_countries(sports_data) do
    sports_data
    |> Enum.map(fn {_sport, country, _league} -> country end)
  end
end

My point is that you only need to parse the CSV once, and that is at compile time.