⋄ — SeparatorAt statement level, ⋄ separates expressions. Newline does the same.
x←2 ⋄ y←3 ⋄ x+y ⍝ 5
Inside array literals, ⋄ separates items/cells. A trailing separator makes a singleton.
(42 ⋄) ⍝ ,42
[1 2 ⋄ 3 4] ⍝ 2 2⍴1 2 3 4