Ets.fun2ms needs ms_transform error

Hello everyone, I have some strange error message when using :ets.fun2ms. I am trying to filter an ets table based on some time. def get_obsolete_check_in(time) do fun = :ets.fun2ms(fn {_, %CheckIn{start_time: start_time}} = check_in when start_time > time -> check_in end) :ets.select(…