Hi all. I was searching for ways to determine whether or not an Ecto query results in (a) result(s) without requiring the database to select columns as I don’t need the data and found this discussion in the Slack archive. @michalmuskala shared this function which one can put in an app’s Repo module…

Thanks. I’ve just tested !!!, and that seems to be not-not-not, so I suppose the reason that !! isn’t explicitly documented (unless I’ve just missed it) is that it’s simply applying additional negation. (By calling a function twice?)

I think so… Doing ! value gives You also boolean, but in the opposite order.

Right. !! isn’t a separate thing any more than not not true is. It’s just double application of a unary operator.

Elixir Programming Language Forum

Double-exclamation mark syntax

Questions & Help Questions

kokolegorille June 21, 2017, 7:59pm 2

It enforces boolean value…

! is not

!! is not not, forcing true or false