Filled pretty printing (where we try to fit as many elements on a line as possible) is being too aggressive as we can see when we try to print the following array:
user> (binding [*print-right-margin* 20] (pprint (int-array (range 10))))
Produces:
[0,
1,
2,
3,
4, 5, 6, 7, 8, 9]
Rather than
[0, 1, 2, 3, 4,
5, 6, 7, 8, 9]
or something like that. (I haven't worked through the exact correct representation for this case).
We currently only use :fill style newlines for native java arrays.