to square :x
  output :x * :x
end
show map "square [1 2 3 4 5]  ; [1 4 9 16 25]
show map [? * ?] [1 2 3 4 5]  ; [1 4 9 16 25]
foreach [1 2 3 4 5] [print square ?]  ; 1 4 9 16 25, one per line