Stream gatherers are just transducers dipped in Java sauce. It's only fair for Clojure to be able to use them as ergonomically as the original.
Just look at the comments in the source, it's quite easy really.
xf is a drop-in replacement for comp which also accepts Gatherer objects;
xf* is your extension point to introduce more coercions.
Note that while most of the behavior is exactly the same in a naive
translation between transducer-producers and Gatherer-xfs, Gatherer-xfs always implicitly honor reduced, which leads to immediate and unavoidable short-circuiting when a reduced is snuck in as an acc e.g. by passing it in as the initializer to a reduction.
This library is meant to facilitate the usage of existing Gatherers where the equivalent Clojure transducers aren't readily available so this shouldn't really be an issue, but it is a useful heads up should you want e.g. to manually re-implement a Gatherer as a transducer.