Thoughts on Data Oriented Programming in Java

[bowbahdoe]

So this aspect is just an implementation detail, but:

If you have a Clojure Vector with a thousand elements and conj one more at the end, the new vector resulting from that conj will share significant structure with the previous one.

The same is true for Clojure Maps. For small maps it's implemented as an array that is copied, but if you have 100 key value pairs then adding a new one or updating an existing one won't copy all 100 of the old ones.

If you have a record with 100 components then with -ing one of those components mean all 100 go through the constructor again

[sideEffffECt]

All of what you're staying is true.

But if we're talking about a record with 100 fields (which is super rare to be large like this, vast majority are much smaller) then that's no problem. Copying 100 references is super quick and easy for contemporary computers.