Re: [Proposal] Optional spreading
On 23. 8. 2019 16:24, Beknar Askarov wrote:
@Scott Rudiger After thinking more about it.
I would not like to conflict with semantics of optional chaining and
null coalescing operator.
So in order to not confuse people, maybe introduce two types of optional
spread operators
1. `?...` - Do not spread if nullish. Note nullish. Else try to spread.
Signature Array: [?...(nullish | Iterable)];
Signature Object: {?...(nullish | object)};
2. `!...` - Do not spread if false. Note FALSE not falsy. Else try to
spread.
I read
!...foo
as
!(...foo)
that is, logical not. I'd tip it already works that way. In which case
no go, break compat.
Herby
Signature Array: [!...(false | Iterable)];
Signature Object: {!...(false | object)};
I think this can be an option to avoid consfusion
Or add a new one. :-(
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Re: [Proposal] Optional spreading
@Scott Rudiger After thinking more about it.
I would not like to conflict with semantics of optional chaining and null
coalescing operator.
So in order to not confuse people, maybe introduce two types of optional
spread operators
1. `?...` - Do not spread if nullish. Note nullish. Else try to spread.
Signature Array: [?...(nullish | Iterable)];
Signature Object: {?...(nullish | object)};
2. `!...` - Do not spread if false. Note FALSE not falsy. Else try to
spread.
Signature Array: [!...(false | Iterable)];
Signature Object: {!...(false | object)};
I think this can be an option to avoid consfusion
Why not `!...` to check for all falsy and do not spread of falsy?
To avoid confusion and make developers to know their types
For example:
```js
[!...(0 ?? [1 , 2])]; // throws TypeError. number 0 is not iterable
```
So better will be to use:
```js
[!...(!!0 ?? [1 , 2])];
// OR
[?...(0 ?? [1 , 2])];
```
What do you think?
On Fri, Aug 23, 2019 at 5:00 AM Beknar Askarov
wrote:
> And it does result in empty array
>
> [...''] -> []
>
> So not much difference even if it passes through. Everything else would
> result in error if check was only nullish
>
> On Fri, 23 Aug 2019, 04:55 Beknar Askarov,
> wrote:
>
>> @Scott My mistake empty string [...""] is spreadable.
>> But not sure if it is desirable behavior.
>>
>>
>> On Fri, 23 Aug 2019, 04:42 Beknar Askarov,
>> wrote:
>>
>>> Indeed. I see your point.
>>>
>>> But it really needs to be falsy check.
>>> Since falsy values are not "spreadable"
>>>
>>>
>>>
>>> On Fri, 23 Aug 2019, 03:52 Scott Rudiger,
>>> wrote:
>>>
I like it; code seems cleaner to me with its use. However, since the
syntax is so similar to optional chaining, it's too bad your goal with this
sample is to check for falsey values rather than nullish values.
[ 1, ?...(condition && [2, 3]), // no extras:) 3, ]
On Thu, Aug 22, 2019, 6:01 PM Beknar Askarov
wrote:
> Problem
>
> Spreading is great! It contributes towards "declerativity" of the
> language and reduces verbosity. I see one more feature to add to improve
> it.
>
> Consider following
>
> [
> 1,
> condition && 2,
> condition && 3,
> 4,
> ].filter(Boolean) // filtering needed to remove falsy values
> // Results in
> [1, 2, 3, 4] // if condition is `truthy`// and
> [1, 4] // if not truthy.
>
> Another way to achieve the same result without the need of filtering
> after
>
> [
> 1,
>...(condition ? [2, 3] : []), // note extra [] in the end, to avoid
> errors
> 4,
> ]
>
> Similar pattern with objects
>
> {
> ...(condition ? { foo: 'bar' } : {}), // extra {}
> }
>
> Another pattern is when condition is the object itself, when it is
> known that type is one or falsy
>
> [
> item1,
> item2,
> ...(itemsOrNull || []) // extra []
> ]
>
> Similar for objects
>
> {
> ...(obj || {}), // extra {}
> }
>
> I see these patterns appearing very often. And these are cleanest
> examples I have seen so far.
> ProposalOptional spreadingWith condition
>
> // Arrays
> [
> 1,
> ?...(condition && [2, 3]), // no extras:)
> 3,
> ]// Objects
> {
> ?...(condition && { foo: 'bar' }) // no extras:)
> }
>
> When condition is the object
>
> [
> item1,
> item2,
> ?...itemsOrNull // no extras at all:) even (...)
> ]
>
> These look nicer and can be good for performance since (?...), since
> no cleanup is needed after to remove falsy values or extra spreading even
> when it is not needed.
>
> Looks intuitive (since:
> https://github.com/tc39/proposal-optional-chaining)
> Plays nice with typeings.
>
> What do you think? https://es.discourse.group/t/optional-spreading/93
>
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Re: [Proposal] Optional chaining
Another similar thing I've used is with String interpolation; if you use a
similar pattern, e.g.,
``` `$[items.length} item${items.length !== 1 ? 's' : ''} in collection` ```
When you want to conditionally add either some text, or nothing at all, you
are forced to use the ternary with an empty string, or some workaround. In
terms of a proposal, the first thing I think we need to know is: can the
interpreter detect that it's in a template literal, in the same manner as
it detects ?... being in an object/array declaration context?
--
Dammit babies, you've got to be kind.
On Fri, 23 Aug 2019 at 02:01, Beknar Askarov
wrote:
> Problem
>
> Spreading is great! It contributes towards "declerativity" of the language
> and reduces verbosity. I see one more feature to add to improve it.
>
> Consider following
>
> [
> 1,
> condition && 2,
> condition && 3,
> 4,
> ].filter(Boolean) // filtering needed to remove falsy values
> // Results in
> [1, 2, 3, 4] // if condition is `truthy`// and
> [1, 4] // if not truthy.
>
> Another way to achieve the same result without the need of filtering after
>
> [
> 1,
>...(condition ? [2, 3] : []), // note extra [] in the end, to avoid errors
> 4,
> ]
>
> Similar pattern with objects
>
> {
> ...(condition ? { foo: 'bar' } : {}), // extra {}
> }
>
> Another pattern is when condition is the object itself, when it is known
> that type is one or falsy
>
> [
> item1,
> item2,
> ...(itemsOrNull || []) // extra []
> ]
>
> Similar for objects
>
> {
> ...(obj || {}), // extra {}
> }
>
> I see these patterns appearing very often. And these are cleanest examples
> I have seen so far.
> ProposalOptional spreadingWith condition
>
> // Arrays
> [
> 1,
> ?...(condition && [2, 3]), // no extras:)
> 3,
> ]// Objects
> {
> ?...(condition && { foo: 'bar' }) // no extras:)
> }
>
> When condition is the object
>
> [
> item1,
> item2,
> ?...itemsOrNull // no extras at all:) even (...)
> ]
>
> These look nicer and can be good for performance since (?...), since no
> cleanup is needed after to remove falsy values or extra spreading even when
> it is not needed.
>
> Looks intuitive (since: https://github.com/tc39/proposal-optional-chaining
> )
> Plays nice with typeings.
>
> What do you think? https://es.discourse.group/t/optional-spreading/93
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> es-discuss@mozilla.org
> https://mail.mozilla.org/listinfo/es-discuss
>
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Re: [Proposal] Optional spreading
Like others said, this idea is good, but I think we can already achieve
something decent and succinct enough
arrays:
```js
// group by name, and accumulate data:
arr.reduce((m, {name, data, ...o}) => m.set(name, {...o, data:
[...m.get(name)?..data||[], ...data]}), new Map())
```
objects: `{foo: 1, ...cond && {bar: 2}, qux: 3}`
https://gist.github.com/caub/7494b4391c2d62c49b565d2cfc2c0c1f#file-fetch-wrapper-js-L11
On Fri, Aug 23, 2019 at 5:01 AM Beknar Askarov
wrote:
> And it does result in empty array
>
> [...''] -> []
>
> So not much difference even if it passes through. Everything else would
> result in error if check was only nullish
>
> On Fri, 23 Aug 2019, 04:55 Beknar Askarov,
> wrote:
>
>> @Scott My mistake empty string [...""] is spreadable.
>> But not sure if it is desirable behavior.
>>
>>
>> On Fri, 23 Aug 2019, 04:42 Beknar Askarov,
>> wrote:
>>
>>> Indeed. I see your point.
>>>
>>> But it really needs to be falsy check.
>>> Since falsy values are not "spreadable"
>>>
>>>
>>>
>>> On Fri, 23 Aug 2019, 03:52 Scott Rudiger,
>>> wrote:
>>>
I like it; code seems cleaner to me with its use. However, since the
syntax is so similar to optional chaining, it's too bad your goal with this
sample is to check for falsey values rather than nullish values.
[ 1, ?...(condition && [2, 3]), // no extras:) 3, ]
On Thu, Aug 22, 2019, 6:01 PM Beknar Askarov
wrote:
> Problem
>
> Spreading is great! It contributes towards "declerativity" of the
> language and reduces verbosity. I see one more feature to add to improve
> it.
>
> Consider following
>
> [
> 1,
> condition && 2,
> condition && 3,
> 4,
> ].filter(Boolean) // filtering needed to remove falsy values
> // Results in
> [1, 2, 3, 4] // if condition is `truthy`// and
> [1, 4] // if not truthy.
>
> Another way to achieve the same result without the need of filtering
> after
>
> [
> 1,
>...(condition ? [2, 3] : []), // note extra [] in the end, to avoid
> errors
> 4,
> ]
>
> Similar pattern with objects
>
> {
> ...(condition ? { foo: 'bar' } : {}), // extra {}
> }
>
> Another pattern is when condition is the object itself, when it is
> known that type is one or falsy
>
> [
> item1,
> item2,
> ...(itemsOrNull || []) // extra []
> ]
>
> Similar for objects
>
> {
> ...(obj || {}), // extra {}
> }
>
> I see these patterns appearing very often. And these are cleanest
> examples I have seen so far.
> ProposalOptional spreadingWith condition
>
> // Arrays
> [
> 1,
> ?...(condition && [2, 3]), // no extras:)
> 3,
> ]// Objects
> {
> ?...(condition && { foo: 'bar' }) // no extras:)
> }
>
> When condition is the object
>
> [
> item1,
> item2,
> ?...itemsOrNull // no extras at all:) even (...)
> ]
>
> These look nicer and can be good for performance since (?...), since
> no cleanup is needed after to remove falsy values or extra spreading even
> when it is not needed.
>
> Looks intuitive (since:
> https://github.com/tc39/proposal-optional-chaining)
> Plays nice with typeings.
>
> What do you think? https://es.discourse.group/t/optional-spreading/93
>
> ___
> es-discuss mailing list
> es-discuss@mozilla.org
> https://mail.mozilla.org/listinfo/es-discuss
>
___
> es-discuss mailing list
> es-discuss@mozilla.org
> https://mail.mozilla.org/listinfo/es-discuss
>
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