[brabel]

It's literally impossible on a CPU. Some people claim FP languages can make optimisations that are based on the fact that values are immutable and which other languages can't, and that's definitely true. But the problem is that those optimisations are almost never actually made by real programming languages, and when they are, they're still slower than a low level imperative language like C or Rust in very nearly every case.

Come'on FP hackers, prove me wrong!

[RandomThoughts3]

No one needs to prove you wrong because that's not where the goal post actually is.

You could craft hand written assembly code which will be faster than optimised C code most of the time yet you don't. Plenty of programmers are perfectly writing imperative code in Java doing a ton of necessary boxing and unboxing. It's all a trade off between performance and usability. The fact is that the Ocaml compiler does a good enough job with functional code that its performance is actually comparable to imperative solutions most of the time.

[p_l]

If you compile your immutable program with LLVM, literally one of the cure steps is transforming it into functional form that does not allow mutations.

This is called Single Static Assignment form and its denial of mutation is crucial to optimization, from common expression removal, to efficient register allocation, and all sorts of control flow analysis.

[eru]

> If you compile your immutable program with LLVM, literally one of the cure steps is transforming it into functional form that does not allow mutations.

You probably wanted to write something like 'If you compile your _mutating_ program with LLVM, [...]'?

[p_l]

Yes. Unfortunately I wrote the answer on the phone, and completely missed the (way more common in my writing) word replacing the right one :/