F sd_mean(numbers)
   V mean = sum(numbers) / numbers.len
   V sd = (sum(numbers.map(n -> (n - @mean) ^ 2)) / numbers.len) ^ 0.5
   R (sd, mean)

F histogram(numbers)
   V h = [0] * 10
   V maxwidth = 50
   L(n) numbers
      h[Int(n * 10)]++
   V mx = max(h)
   print()
   L(i) h
      print(‘#.1: #.’.format(L.index / 10, ‘+’ * (i * maxwidth I/ mx)))
   print()

L(i) (1, 5)
   V n = (0 .< 10 ^ i).map(j -> random:())
   print("\n####\n#### #. numbers\n####".format(10 ^ i))
   V (sd, mean) = sd_mean(n)
   print(‘  sd: #.6, mean: #.6’.format(sd, mean))
   histogram(n)