From a quick test (through Python), it seems that slice and take work, but the following not:

• cast: it could rely on the casting rules for the storage type. Or do we want that you explicitly have to take the storage array before casting?
• dictionary_encode / unique

Reporter: Joris Van den Bossche / @jorisvandenbossche
Watchers: Rok Mihevc / @rok

Related issues:

• [C++] C++ array kernels framework and execution buildout (umbrella issue) (is a child of)
• [C++][CSV] Add support for Extention type in csv reader (relates to)
• [C++][Python] Support casting an Extension type to its storage type (relates to)

_{Note: This issue was originally created as ARROW-5890. Please see the migration documentation for further details.}