# Set and Range objects and literals
**URL:** https://es.discourse.group/t/set-and-range-objects-and-literals/1750
**Category:** 💡 Ideas
**Created:** [July 7, 2023, 12:19am UTC](https://es.discourse.group/t/set-and-range-objects-and-literals/1750 "2023-07-07T00:19:02Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@dspeyer](https://es.discourse.group/u/dspeyer)
#### Post date: [July 7, 2023, 12:19am UTC](https://es.discourse.group/t/set-and-range-objects-and-literals/1750/1 "2023-07-07T00:19:02Z")
Expanding my comment from [the chaining comparitor proposal](https://es.discourse.group/t/operators/1577/30)...
Currently we write:
```
if (longVariableName == 'p' || longVariableName == 'div') {...}
if (effectiveMousePos.x <= right && effectiveMousePos.x >= left) {...}
```
and it's annoyingly verbose. Instead, I'd like to write:
```
if (longVariableName in {{p, div}}) {...}
if (effectiveMousePos.x in []) {...}
```
Sets are kind of like maps, so you can write (I have written)
```
if (longVariableName in {p:1, div:1}) {...}
```
but the irrelevant values are distracting, so it's awkward. Doubly so if there's a formatter or style rule that insists on thinking of the set as a map.
Literals and `in` tests are the case I most care about, but as long as we're doing this...
- `set[key] = True/False` adds or removes a key from a set
- sets take `*`, `+`, and `-` operators for intersection, union, and set-difference, with obvious `*=`, `+=`, and `-=`.
- `for (i in set)` does this obvious
- ranges have members `start`, `end`, `min`, and `max`. The first two are ordered based on definition, the latter based on comparison.
- `for (i of range) ` starts at `min`, then adds 1 until `i` exceeds `max`
- `for (i of range.by(step))` does the same except that it adds `step` each time. If `step` is negative, it starts from `max`.
---
### Author:  [@bakkot](https://es.discourse.group/u/bakkot)
#### Post date: [July 7, 2023, 12:41am UTC](https://es.discourse.group/t/set-and-range-objects-and-literals/1750/2 "2023-07-07T00:41:08Z")
It's probably not worth adding syntax for this.
For your first use case, `['p', 'div'].includes(longVariableName)` already exists, is sufficient, and is plenty fast (you need a surprisingly amount of data before membership tests start being slower for arrays than for hashmaps, certainly more than it would be sensible to write inline).
---
### Author:  [@0X-JonMichaelGalindo](https://es.discourse.group/u/0X-JonMichaelGalindo)
#### Post date: [July 14, 2023, 11:51am UTC](https://es.discourse.group/t/set-and-range-objects-and-literals/1750/3 "2023-07-14T11:51:56Z")
How would this syntax handle logic?
```javascript
if( x > left && x < right ) ...
//vs.:
if( x > left || x < right ) ...
```
---
### Author:  [@rdking](https://es.discourse.group/u/rdking)
#### Post date: [August 24, 2023, 7:13pm UTC](https://es.discourse.group/t/set-and-range-objects-and-literals/1750/4 "2023-08-24T19:13:17Z")
Try this:
```js
//Yours
if (effectiveMousePos.x <= right && effectiveMousePos.x >= left) {...}
//Alternative (loose)
if ({with(effectiveMousePos) {x <= right && x>= left}}) {...}
//Alternative (strict)
if ((({x}) => (x <= right && x>= left))(effectiveMousePos)) {...}
```