Almost all type-theoretical treatments of references that I\'ve studied introduc

Question

Almost all type-theoretical treatments of references that I've studied introduce references as accompanied with at least three operations (sometimes including the fourth):

Construction (allocation): ref e
Elimination (dereferencing): !e
Updating: e1:=e2
(not as common) Destruction (deallocation): free e

My question is this: Would references be of any use without updating (construct #3 above)? If so, what would be a common use? Does the ability to use updates with references lend any more "power" to a language? You can answer assuming either the presence or absence of construct #4 above; if it affects your answer, please explain how.

Explanation / Answer

References are useful even if you don't update the object, since copying objects takes memory and time. When passing a reference, only a pointer is passed. But suppose that you were passing a string - it could take far longer to copy the entire string. This is why language like C++ support constant references, which are references that cannot be updated.

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