[ruby-core:98070] [Ruby master Feature#16818] Rename `Range#%` to `Range#/`

Issue #16818 has been updated by zverok (Victor Shepelev).


I'd say that `(5..14) / 3` reads definitely like "split the range into 3 parts" (expecting, IDK, 3 sub-ranges or jumps over `(14-5) / 3` spans). 

`(5..14) % 3` at least reads (for me) like "range 5—14 `<something>` 3", bearing no immediate association (as we use % for reminders, and for formatting, and for array literals), and can be just memoized.

That being said, I am not sure the syntax has some significant usage currently, I am not sure whether it is due to the syntax itself, or due to the fact no Ruby objects support it (which I am trying to solve in #16812), or that majority of Ruby usage in the wild doesn't require slicing-with-step at all.

----------------------------------------
Feature #16818: Rename `Range#%` to `Range#/`
https://bugs.ruby-lang.org/issues/16818#change-85297

* Author: sawa (Tsuyoshi Sawada)
* Status: Open
* Priority: Normal
----------------------------------------
`Range#%` was introduced as an alias of `Range#step` by 14697, but it is counter-intuitive and confusing.

Iteration in the following:

```ruby
((5..14) % 3).each{|i| p i}
#>> 5
#>> 8
#>> 11
#>> 14
```

is not based on `x % y` in any sense. In fact, actually applying `% 3` to the selected elements returns a unique value `2`, and it is not obvious how this is related to the iteration.

```ruby
[5, 8, 11, 14].map{|i| i % 3}
# => [2, 2, 2, 2]
```

Rather, the concept seems to be based on `/`. Applying `/ 3` to the relevant elements returns a sequence `1, 2, 3, 4`.

```ruby
[5, 8, 11, 14].map{|i| i / 3}
# => [1, 2, 3, 4]
```

Hence, `(5..14).step(3)` can be interpreted like this: Iterate over the [equivalence class](https://en.wikipedia.org/wiki/Equivalence_class) (quotient set) of range `5..14` yielded by `/ 3`.

Notice that the number of elements in `[5, 8, 11, 14]` is 4, which is `(14 - 5 + 1) / 3.0).ceil`, but is not related to `%`.

So I propose that the alias of `Range#step` should be `Range#/`, and `Range#%` should be deprecated as soon as possible before its use accumulates:

```ruby
((5..14) / 3).each{|i| p i}
#>> 5
#>> 8
#>> 11
#>> 14
```

---

P.S.

And if `Range#%` were to be introduced at all, I would rather expect it to behave like the following:

```ruby
((5..14) % 3).each{|i| p i}
#>> 5
#>> 6
#>> 7
```

which is why I claimed above that the current `Range#%` is confusing.



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