Your analysis sounds reasonable to the non-expert, but recent work on purely-functional trees suggests that the gap is smaller than you suggest ("orders of magnitude slower").
E.g., see the nice work on the PAM library (https://arxiv.org/abs/1612.05665). Ideas from this work were used to build lots of cool things (immutable graph data structures, segment trees, databases) that are very fast, and all immutable.
This shit is all lies dude. In measurements like this, they constrain mutable structures to the same memory layouts and ideas as immutable ones and say “see! Sometimes kinda close!”
> bog standard FP community lies
> constrain mutable structures to the same memory layouts and ideas as immutable ones
What are you even talking about, "dude"? I don't think you have the background or knowledge you seem to think you have to argue about this space. It's OK, as you blithely pointed out in your earlier post, there is a place called medium where you'll find likeminded folks that will eat up your drivel.
Interestingly, medium is the place pushing idiotic “always runtime immutable or ur dumb” nonsense, resulting in this blog post because people such as yourself are eating it up on the basis of moronic bullshit like “beautiful”.
>what are you even talking about
I am talking about your own posts, perpetuating more moronic FP lies
>background
Nobody needs background to see that needlessly copying data for no reason is more expensive than not doing that.
Unfortunately for FP programmers, the moronic levels of doing this is actually worse than it sounds, as needlessly copying data is basically completely antithetical to how every modern CPU wants to optimally work.
It isn’t “me” declaring that runtime immutability is moronic. It is your CPU telling you that.
Given the age of your account my guess is that you're still young with too strong opinions and too little experience. That's ok, we all start there. But I can tell you from experience, that you'll need to outgrow that mindset in order to grow intellectually.
The difference between mutability and immutability is not as clear cut as you think, and might just be the difference between a `& mut` and a `&`.
E.g., see the nice work on the PAM library (https://arxiv.org/abs/1612.05665). Ideas from this work were used to build lots of cool things (immutable graph data structures, segment trees, databases) that are very fast, and all immutable.