Why does "each"-ing a range only work with incrementing ranges? [duplicate]

Question

This makes absolutely no sense:

irb(main):001:0> (1..10).each do |x|
irb(main):002:1*   puts x
irb(main):003:1> end
1
2
3
4
5
6
7
8
9
10
=> 1..10

whereas:

irb(main):004:0> (10..1).each do |x|
irb(main):005:1*   puts x
irb(main):006:1> end
=> 10..1

What's the point in offering a range iterator and support for decrementing ranges if you can't mix and match the two? Is this something fixed in newer versions of ruby? (running windows)

Answer 1

It turns out that decrementing ranges are not supported. Indeed 10..1 is of class range, but iterating over it produces no results (consider (10..1).to_a, an empty list)

Answer 2

Ranges in Ruby only use for incrementing values. This can be used for numbers

(1..5).to_a
[1,2,3,4,5]

or even letters

('a'..'e').to_a
['a','b','c','d','e']

There are other options you could try though. You could do

10.downto(1).to_a

In Ruby, ranges use the <=> operator to determine if an iteration is over;

5 <=> 1 == 1
5 is greater than 1

The next value would be 4 which is not greater than 5 but rather less then.

Update: Added explanation