This has bitten me a couple times too but it's usually easy to figure out the first time you botch it and you're more careful after that. Immutability is doubl

This has bitten me a couple times too but it's usually easy to figure out the first time you botch it and you're more careful after that. Immutability is double edged. If I'm doing a bunch of math on a date, I don't want to be creating a dozen copies either. SQL query builders also have this problem.