Thank you for making the effort the author's couldn't be bothered to.
It's horrible btw. You can't even tell if and when order in this syntax is important.
It's also not clear if it's declarative or operational syntax. But since they are compiling to SQL it has to be the first. Yet the syntax strongly misleads people into assuming a particular execution strategy.
Not even naming of things is consistent (why shorten "array" into "arr" but not minute into "min").
It just looks like random syntax choices, without a cohesive rationale made by people that think the declarative syntax of SQL looks worse than for-loops, completely ignoring that the database will not execute anything the way it is structured here.