graue

    var fooString = "foo";
    var secondFooString = fooString;
    secondFooString;  // => "foo"
    
    fooString = "bar";
    secondFooString;  // => "foo"

    var firstArray = [1, 2, 3];
    var secondArray = firstArray;
    
    firstArray[0] = 100;
    firstArray;  // => [100, 2, 3]
    secondArray;  // => also [100, 2, 3]

    var firstVec = m.vector(1, 2, 3);
    var secondVec = firstVec;
    
    firstVec = m.assoc(firstVec, 0, 100);
    firstVec;  // => [100, 2, 3]
    secondVec;  // => still [1, 2, 3]

The most obvious way to build this would be to deep-copy the entire collection when it's changed, but that would of course be way too slow and wasteful — imagine copying a one-million-long array just to change one element. Clojure, ClojureScript and Mori minimize unnecessary copying using a very thoughtfully designed data structure you can read about here: http://hypirion.com/musings/understanding-persistent-vector-... The short story is that, surprisingly, you get "effectively O(1)" copying when you use assoc.

See: http://hypirion.com/musings/understanding-persistent-vector-...

https://en.wikipedia.org/wiki/Singular_they

Some object to the usage because:

> Proponents of gender-neutral language argue that the use of gender-specific language often implies male superiority or reflects an unequal state of society. According to The Handbook of English Linguistics, generic masculine pronouns and gender-specific job titles are instances "where English linguistic convention has historically treated men as prototypical of the human species." Words that refer to women often devolve in meaning, frequently taking on sexual overtones.

> These differences in usage are criticized on two grounds: one, that they reflect a biased state of society, and two, that they help to uphold that state. Studies of children, for instance, indicate that the words children hear affect their perceptions of the gender-appropriateness of certain careers. Other research has demonstrated that men and women apply for jobs in more equal proportions when gender-neutral language is used in the advertisement, as opposed to the generic he or man.

https://en.wikipedia.org/wiki/Gender-neutral_language_in_Eng...

Many years ago, I would have agreed with you that using "he" as neuter was correct and therefore preferable to singular "they". I no longer feel that way. I'd attribute that change in opinion to two causes:

One, I'm less concerned with by-the-book "correctness" and pedantry, and more concerned with the real-world effect my words have on people.

Two, I now realize that English is a living, evolving language, and there is no one authority on what is or is not correct usage. What is widely held to be proper English at a given time is a product of who happened to have influence in society at that time, no more, no less.

Also, although this is not what changed my opinion, I find it interesting to note that many of the same people who call the matter trivial will also expend considerable time and effort defending generic "he". If you find it so trivial, why not humor the people who think gender-neutral language is important?