If (1...10) doesn't yield a list of numbers from 1 to 10 inclusive, that's a bug in Ruby. The problem is not density. It's perfectly clear what this code example should mean.
irb(main):001:0> (1..10).max
=> 10
irb(main):002:0> (1...10).max
=> 9
>>> range(1,10)
[1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> range(10)
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
[1]> (dotimes (i 10) (format t "~d" i))
0123456789
NIL