Why a macro at all? If you had written it as a function, then there would be no noeed to quote and unquote…

def up do
  execute_sql_as_one_per_line(file_reader())
end

def execute_sql_as_one_per_line(sql_list) do
  Enum.each(sql_list, &execute/1)
end

Or even simpler, have it inline:

def up do
  Enum.each(file_reader(), &execute/1)
end

Great! That worked. It needed a little cleanup in the sql files in order to work, but it does now.

For anyone interested: If you have a List/Array of sql statements, you can use a simple macro like:

  defmacro execute_sql_as_one_per_line(sql) do
    quote do
      Enum.each(unquote(sql), fn statement ->
        execute(statement)
      end)
    end
  end

in your up migration:

  def up do
    sql = file_reader()

    execute_sql_as_one_per_line(sql)
  end

By default Ecto uses prepared statements (this is like a precompiled form of the statement which is the cached so that reuse is materially faster).

There is an option prepare: :unnamed which I think goes on the Repo configuration (its a Postgrex adapter option) but I can’t recall and I’m in China this week so googling isn’t an option.

Sorry its an incomplete answer but hopefully thats enough to get you started…