Java collection types currently print as

#<ClassName {toString rep}>

As a result, their contents are not subject to control via Clojure's flags:

*print-length*, *print-level*

This is a big pain when working with big Java data at the REPL. I propose that, when their print forms are not overridden in derived classes, objects that implement the core Java collection interfaces print

• with the same rep as Clojure's persistent collections
• subject to the various print binding flags

Not in scope

• Per Rich's comment in the discussion, Java collections should not expose their type in print rep, so an array list should print as e.g.  [1 2] like any other sequential collection. 
• print-dup 
• Print/read roundtripping to a specific concrete type