The java interop is very verbose and kind of ugly (next to "pure" clojure code anyway) so many clojure wrappers or reimplmentations for existing Java libraries

The java interop is very verbose and kind of ugly (next to "pure" clojure code anyway) so many clojure wrappers or reimplmentations for existing Java libraries exist. So yes, sometimes it's as simple as extending the wrapper to expose the part of the underlying Java library you need, but other times there are fundamental issues with the design of the library that prevent it from being useful in a multi-threaded multi-user server environment (instancing etc).