# Pastebin mZJhLJLa
map = %{created_at: "2017-01-19T08:32:26+02:00", updated_at: "2017-01-19T08:32:26+02:00"}

converted = Map.new(map, fn
  {key, created_at} when key in [:created_at, :updated_at] ->
    {key, DateTime.from_iso8601!(created_at)}
  other ->
    other
end)