I'm not familiar with APL, but after seeing the examples from Wikipedia [1], I think I know what you mean:
# generates a typical set of Pick 6 lottery numbers
x[⍋x←6?40]
# finds all prime numbers from 1 to R
(~R∊R∘.×R)/R←1↓⍳R
# game of life
life←{↑1 ⍵∨.∧3 4=+/,¯1 0 1∘.⊖¯1 0 1∘.⌽⊂⍵}