So are you saying that for instance both CaML and LISP aren't FP ? Because both are certainly not about immutability and you can write mutable messes in either.
Read the first line:
"In computer science, functional programming is a programming paradigm—a style of building the structure and elements of computer programs—that treats computation as the evaluation of mathematical functions and avoids changing-state and mutable data. It is a declarative programming paradigm, which means programming is done with expressions[1] or declarations[2] instead of statements."
Key phrase: "avoids changing-state and mutable data."
You can use C++ as if it was a functional language just like you can use LISP and CaML as if variables were mutable. However in both cases you are bending the language to follow a paradigm that is NOT functional.
>The only technical requirement for you to follow the functional paradigm is immutability.
Then you don't understand functional programming. I can't take you seriously if you claim otherwise.
Obviously, you highly disagree with me. Feel free to elaborate rather than waste my time with obviously rhetorical questions.