I agree with Mark here plus we have const now which is perfect for
something like this if you wanted to take DRY to an extreme.
Ultimately seeing a function declared is obvious, seeing a special key word
is not. I have been in software development close to 15 years now and when
I first saw this I had to look up to remind myself what identity and noop
referred to (used the concepts many times but frequently forget what
they're called).
Sometimes DRY can be taken too far. This is one of those times IMO.
On Aug 10, 2016 7:33 AM, "Mark S. Miller" <erig...@google.com> wrote:
>
>
> On Wed, Aug 10, 2016 at 7:25 AM, Eli Perelman <e...@eliperelman.com> wrote:
>
>> I can understand the sentiment of wanting brevity and avoiding
>> unnecessary abstraction, but in some cases I think it comes at the cost of
>> readability or good practice. This is why variables exist at all: to store
>> commonly used values either for reuse or to cut down on unnecessary
>> allocation.
>>
>> Sure, I could write code to ensure my numbers did go over a certain limit
>> with `Math.min(userInput, 9007199254740991)`, but readability and
>> abstraction give me something without having to keep this knowledge
>> internally and create my own allocation, e.g. `Math.min(userInput,
>> Math.MAX_SAFE_INTEGER`.
>>
>
> My message is about tradeoffs -- weighing costs against benefits. The
> costs I raise are cognitive burden.
>
> `x => x` has lower cognitive burden than `Function.IDENTITY`
> `9007199254740991` has much higher cognitive burden than
> `Math.MAX_SAFE_INTEGER`
> `3.141592653589793` has much higher cognitive burden than `Math.PI`
> `3` has lower cognitive burden than `Math.THREE`
>
>
>
>
>>
>> Now obviously it would be trivial for me to declare these constants in
>> userland code like I already do, e.g. `const NOOP = () => {}`
>>
>
>
> If there was a reason to do that, then it might make sense to consolidate
> these. However, this definition looks to me like a userland
>
> `const THREE = Math.THREE;`
>
> Whether in userland or not, such an "abstraction" only subtracts value.
>
>
>
>
>> , but in projects where it's needed in several files, I'll have to put
>> that in a module or re-declare everywhere. This is not a huge inconvenience
>> but something that could easily allocated for in the language.
>>
>> > The semantics of the named forms can be guessed rather well from the
>> names, but one cannot be sure without looking up or remembering their
>> definitions.
>>
>> This is true of anything; you know what you know, and are unsure of what
>> you are unsure of. Those that understand what a no-ops and identity
>> functions are will not need to look it up, and those that do not will look
>> it up until they know it. Just like my personal enemies `Array#shift` and
>> `Array#unshift`, I have to look those up every single time, and just
>> because I can't remember which is which or their individual case doesn't
>> mean they don't have value or that I resort to other tricks to avoid their
>> usage. All that to say, I don't think lack of knowledge is a valid argument
>> for these constants' non-inclusion. :)
>>
>> > Only pay these costs when the potential benefits are real.
>>
>> I think my allusion to potential benefits is avoidance of re-declaration
>> (DRY) and allocation.
>>
>> Just my thoughts. :)
>>
>> Eli Perelman
>>
>>
>>
>> On Wed, Aug 10, 2016 at 9:08 AM Mark S. Miller <erig...@google.com>
>> wrote:
>>
>>> On Wed, Aug 10, 2016 at 2:10 AM, Isiah Meadows <isiahmead...@gmail.com>
>>> wrote:
>>>
>>>> I'll note that it's longer than just typing them out manually (and
>>>> close if they're aliased):
>>>>
>>>> ```js
>>>> Function.IDENTITY
>>>> IDENTITY
>>>> x => x
>>>>
>>>> Function.NOOP
>>>> NOOP
>>>> () => {}
>>>> ```
>>>>
>>>> Not sure if it adds anything.
>>>>
>>>
>>> Even aside from brevity, `x => x` and `() => {}` are more readable than
>>> `Function.IDENTITY` and `Function.NOOP` for a very simple reason. The
>>> semantics of the shorter forms are obvious and clear, give knowledge only
>>> of the core language. The semantics of the named forms can be guessed
>>> rather well from the names, but one cannot be sure without looking up or
>>> remembering their definitions. As we all know, abstraction has tremendous
>>> potential benefits. But it also has these costs -- the need to learn the
>>> meaning of new definitions. Only pay these costs when the potential
>>> benefits are real.
>>>
>>> Also, other things being equal, a briefer form is easier to read. In
>>> this case, other things are not equal but both considerations point in the
>>> same direction.
>>>
>>>
>>>> On Tue, Aug 9, 2016, 14:44 Eli Perelman <e...@eliperelman.com> wrote:
>>>>
>>>>> I'm not sure if something like this has been proposed before, but I
>>>>> often find myself declaring constants for the identity function and the
>>>>> no-op function. I think it would be useful to have constants available on
>>>>> Function containing these values. For example `Function.IDENTITY` and
>>>>> `Function.NOOP`. Essentially these constants would map to:
>>>>>
>>>>> ```js
>>>>> Function.IDENTITY = (a) => a;
>>>>> Function.NOOP = () => null; // or:
>>>>> Function.NOOP = () => {};
>>>>> ```
>>>>>
>>>>> These could then be used in places where non-user-controlled APIs need
>>>>> default functions need to be executed, or as placeholders for default
>>>>> values that may be executed before a function has been supplied. For
>>>>> example:
>>>>>
>>>>> ```js
>>>>> // third-party API requires a callback or throws, but no functionality
>>>>> really needs to done:
>>>>> thirdParty.action(Function.NOOP);
>>>>>
>>>>> // Function needs a default which *may* execute prior to having a
>>>>> different one specified (contrived):
>>>>> const action = (handler = Function.IDENTITY, value = 10) =>
>>>>> handler(value);
>>>>> ```
>>>>>
>>>>> Thoughts? Seems like something simple with positive value. Thanks!
>>>>>
>>>>> Eli Perelman
>>>>> _______________________________________________
>>>>> 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
>>>>
>>>>
>>>
>>>
>>> --
>>> Cheers,
>>> --MarkM
>>>
>>
>
>
> --
> Cheers,
> --MarkM
>
> _______________________________________________
> es-discuss mailing list
> es-discuss@mozilla.org
> https://mail.mozilla.org/listinfo/es-discuss
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>
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