pprint not always printing items on separate lines

user=> (pprint (for [x [1 2 3] y [1 2 3] z [:a :b]] [x y z]))
([1 1 :a]
 [1 1 :b]
 [1 2 :a]
 [1 2 :b]
 [1 3 :a]
 [1 3 :b]
 [2 1 :a]
 [2 1 :b]
 [2 2 :a]
 [2 2 :b]
 [2 3 :a]
 [2 3 :b]
 [3 1 :a]
 [3 1 :b]
 [3 2 :a]
 [3 2 :b]
 [3 3 :a]
 [3 3 :b])
nil
user=> (pprint (for [x [1 2 3] y [1 2 3] z [:a :b] :while (not= x y)] [x y z]))
([1 2 :a]
 [1 2 :b]
 [1 3 :a]
 [1 3 :b]
 [2 1 :a]
 [2 1 :b]
 [2 3 :a]
 [2 3 :b]
 [3 1 :a]
 [3 1 :b]
 [3 2 :a]
 [3 2 :b])
nil
user=> (pprint (for [x [1 2 3] y [1 2 3] :while (not= x y) z [:a :b]] [x y z]))
([2 1 :a] [2 1 :b] [3 1 :a] [3 1 :b] [3 2 :a] [3 2 :b])
nil