ldb

Good explanation! (which indicates why the handling of empty sets is sometimes a bit confusing)

One more question: What was the motivation behind defining "sum({})" to be "0" rather then "{}" ?

Thanks, that was helpful. However, I still think that having "sum(1,1,{})" returning "2" and "1+1+{}" returning "{}" can be viewed as somewhat inconsistent.

I am still a bit unclear about this. Assume we have three actor records where two records have age=30 and for the remaining one the age is not set. From what I understand then "SELECT sum(age) FROM Actor;" returns "60" while "SELECT 30 + 30 + {}" returns "{}". This appears to be an inconsistent handling of empty sets (thought it would be the same as in SQL).

Assume I have a table "Actors" with a column "age" and for some of the records the age is not set (an empty set). Does this mean that "SELECT SUM(age) FROM Actors;" gives "{}" or do you implement a special logic for empty-set summation when used in connection with aggregation (like SQL does)?

> any element-wise operation on an empty set is, likewise, an empty set

Does this mean that "SELECT 1 + {}" gives "{}"?

How do I test for empty set? If I understand correctly then "SELECT * FROM Movies WHERE description = {};" will not work, right?

I like the idea. Reminds me of the Eve language/IDE (www.witheve.com).

Very nice work! Love the Mac Classic look :-)