Papers from the Lost Culture of Array Languages (2011)
With many languages adopting LINQ object querying, I find it more and more suitable to start using math's set operators for them. Many languages have almost identical behavioral sequence operators (.find in js, .Where in C#, etc) but math sort-of standardizes them all with a sound theoretical background. I'm not entirely sure if they all map 1-to-1, but at least most will.    const items = ∅; // empty set
    if (myItem ∈ items) { ... } // is element of
    const union = items ∪ otherSet;
    assert items ≌ ∅; // items are all equal