<@U484XHUKB> without the compiler guaranteeing reg...

# random

[hasen]

@johnl without the compiler guaranteeing regarding immutability, I would have to be very defensive and clone a list before passing it to any function just in case that function decides to modify it (think about someone coming along later and changing the function). This creates unnecessary copying. Not having to do that removes the unnecessary copying thus resulting in better performance.