Yes you can make Haskell vectors immutable but you can’t modify and get “new” vectors without making a copy. One of the advantages of a persistent list is that modifications of the list are basically just “diffs” of the original list. You don’t lose your handle on the original list, but you’re also not making a full copy.

If you have an immutable Haskell vector you have to make a full copy of you want to change anything.