⌝ — Outer product

X g⌝Y applies g to every pair. Two atoms call g directly. Array arguments supply the result shape (⍴X),⍴Y.

5+⌝5               ⍝ 10
5+⌝⊂5              ⍝ ⊂10
1,⌝2               ⍝ 1 2
1 2+⌝10 20         ⍝ [11 21 ⋄ 12 22]
(⍳3)=⌝⍳3           ⍝ [1ₓ 0ₓ 0ₓ ⋄ 0ₓ 1ₓ 0ₓ ⋄ 0ₓ 0ₓ 1ₓ]

Array frames collect pair results as items. See inner product.