Immutability doesn't mean no one can implement a Haskell extension that allows safely describing and composing operations that use mutability on the inside. Of

Immutability doesn't mean no one can implement a Haskell extension that allows safely describing and composing operations that use mutability on the inside. Of course on current hardware with current compiler Haskell programs tend to be slower, and also tend to be more correct compared to C/C++ (maybe even compared to let's say C++20).