Oh, thanks. I should have mentioned comprehensions. It’s really just a case of thinking that filter might convey the intent more clearly than a comprehension, and then finding that the syntax didn’t work as cleanly.
In fact, I’m trying to filter a Dict with a Set of keys. It would be really nice if an intersection worked:
d = Dict("a" => 1, "b" => 2, "c" => 3)
s = Set(["a", "c"])
d ∩ s # doesn't work - fair enough because it's trying to match the pairs in `d`