Re: [go-nuts] Re: Possible Go 2 proposal for built-in Remove method for Slices.

2021-02-06 Thread Jan Mercl 
On Sat, Feb 6, 2021 at 8:01 PM Axel Wagner
 wrote:

> FTR, I think even a library function that is defined as "the equivalent of 
> `append(a[:i], a[j:]...)`" (for example) would provide value.

Yes, but IMO a net negative value. Many people will then mindlessly
just use this O(n) variant even though in many cases the O(1) version
could and should be used instead.

Also, note how easy it is to fall into the O(n^2) trap with this
definition of "remove".

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Re: [go-nuts] Re: Possible Go 2 proposal for built-in Remove method for Slices.

2021-02-06 Thread 'Axel Wagner' via golang-nuts 
FTR, I think even a library function that is defined as "the equivalent of
`append(a[:i], a[j:]...)`" (for example) would provide value.
That being said, I also think having this discussion now seems pointless.
Any of it will clearly not happen before generics land (or are rejected),
which is still at least a year out, AIUI. And even then, it'll probably
will be at least another go release or two to see how people use generics
and evaluate the usefulness of it. So litigating the pros and cons of a
package we can't even write for at least a year and won't have tangible
data available to base a decision off of for another one seems futile to me.
YMMV, of course.

On Sat, Feb 6, 2021 at 7:24 PM Jan Mercl <0xj...@gmail.com> wrote:

> On Sat, Feb 6, 2021 at 5:36 PM Sean  wrote:
>
> > I think there is definitely a need for a built-in "remove" function for
> arrays and slice.
> > Everyone is writing their own implementation for this, it is both
> confusing and "x = append(a[:x], b[x:])" like blablabla is not readable.
>
> Please define the semantics of "remove" operation. IINM, that has not
> yet been done in this thread.
>
> Note that "removes an element" of a slice is not an acceptable
> specification. That's circular and useless.
>
> The specification must define what happens to which elements of the
> slice. Additionally it must be specified what are valid arguments of
> "remove" and what will happen if they are not valid.
>
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> .
>

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Re: [go-nuts] Re: Possible Go 2 proposal for built-in Remove method for Slices.

2021-02-06 Thread Jan Mercl 
On Sat, Feb 6, 2021 at 5:36 PM Sean  wrote:

> I think there is definitely a need for a built-in "remove" function for 
> arrays and slice.
> Everyone is writing their own implementation for this, it is both confusing 
> and "x = append(a[:x], b[x:])" like blablabla is not readable.

Please define the semantics of "remove" operation. IINM, that has not
yet been done in this thread.

Note that "removes an element" of a slice is not an acceptable
specification. That's circular and useless.

The specification must define what happens to which elements of the
slice. Additionally it must be specified what are valid arguments of
"remove" and what will happen if they are not valid.

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[go-nuts] Re: Possible Go 2 proposal for built-in Remove method for Slices.

2021-02-06 Thread Sean 
I think there is definitely a need for a built-in "*remove*" function for 
arrays and slice.
Everyone is writing their own implementation for this, it is both confusing 
and "x = append(a[:x], b[x:])" like blablabla is not readable.


5 Şubat 2021 Cuma tarihinde saat 02:55:36 UTC+3 itibarıyla 
selahad...@gmail.com şunları yazdı:

> Hi,
> I wonder if there are any proposals for the Remove method for Slices, 
> which removes an element from a Slice. 
>  
> Since the status of the latest generics draft is `likely accepted` and 
> it'd be possible to implement this with `generics`. I believe such an 
> addition to language would alleviate the need to `loop + swap + resize` 
> each time, and enhance the overall readability since there is a consensus.
>
> This may seem trivial, but I want to highlight some examples from other 
> langs just to further* concretize*:
> arraylist.remove(object o) => java
> list.remove(val) => python
> array.remove(at: 0) => swift 
>
> I have looked for the proposals for Go 2 but couldn't find any regarding 
> this issue.
>
> There are obviously more things to consider, like whether the operation 
> should keep the order. 
>
> I'd be very happy with your responses to this pseudo-proposal.
>
>

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Re: [go-nuts] Re: Possible Go 2 proposal for built-in Remove method for Slices.

2021-02-05 Thread Artur Vianna 
it may be useful to avoid repetition, for example if implementing stacks,
you have to create the "pop(), push(), top()" before starting to code what
you want.

Maybe there's place for this utility functions under the "container/"
package (like "container/slice"), where you could do things like:

st := slice.New([]byte{})
st.Push(1)
b := st.Pop()
st.Queue(b)
b = st.Dequeue()

st.Add(2)
st.DeleteIndex(0)
st.Add(7)
st.DeleteItem(7)

etc

On Fri, 5 Feb 2021, 10:45 Matthew Holiday, 
wrote:

> See also this graphical cheat sheet:
> https://ueokande.github.io/go-slice-tricks/
>
> On Fri, Feb 5, 2021 at 2:09 AM Brian Candler  wrote:
>
>> See: https://github.com/golang/go/wiki/SliceTricks#delete
>> (and lots of other neat tricks there).
>>
>> There's no need to add new syntax or functions when the existing ones do
>> the job.
>>
>> On Thursday, 4 February 2021 at 23:55:36 UTC selahad...@gmail.com wrote:
>>
>>> Hi,
>>> I wonder if there are any proposals for the Remove method for Slices,
>>> which removes an element from a Slice.
>>>
>>> Since the status of the latest generics draft is `likely accepted` and
>>> it'd be possible to implement this with `generics`. I believe such an
>>> addition to language would alleviate the need to `loop + swap + resize`
>>> each time, and enhance the overall readability since there is a consensus.
>>>
>>> This may seem trivial, but I want to highlight some examples from other
>>> langs just to further* concretize*:
>>> arraylist.remove(object o) => java
>>> list.remove(val) => python
>>> array.remove(at: 0) => swift
>>>
>>> I have looked for the proposals for Go 2 but couldn't find any regarding
>>> this issue.
>>>
>>> There are obviously more things to consider, like whether the operation
>>> should keep the order.
>>>
>>> I'd be very happy with your responses to this pseudo-proposal.
>>>
>>> --
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>> 
>> .
>>
>
>
> --
> *Matt Holiday*
> Senior Gopher, Marketing Technologies
>
> 620 Eighth Avenue
>
> New York, NY 10018
>
> matthew.holi...@nytimes.com
>
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> 
> .
>

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Re: [go-nuts] Re: Possible Go 2 proposal for built-in Remove method for Slices.

2021-02-05 Thread Jan Mercl 
On Fri, Feb 5, 2021 at 3:46 PM Fernando Meyer  wrote:

> I understand the pragmatism behind having or not features in the language and 
> its standard library. But, almost all the golang projects I've worked with 
> implement their own utility function to remove elements from a slice, 
> sometimes with order in place, others not. Mostly always these home-brewed 
> libraries ignore bounds-checking introducing runtime problems if the user is 
> not careful enough.
>
> That said, when a feature becomes a ubiquitous necessity across so many 
> codebases, I believe it should be considered to have a standard 
> implementation.

There are two incompatible algorithms for removing an element from a
slice. One moves any remaining elements down, the other moves only the
last element in the place of the removed one.

Which one is the "standard implementation" and why?

The next question will be, why limit ourselves to removing always only
one element, why not generalize to N elements?

The next question will be, do we need to zero the now unused portion
of the slice? It matters sometimes a lot, but it's just overhead where
it does not.

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Re: [go-nuts] Re: Possible Go 2 proposal for built-in Remove method for Slices.

2021-02-05 Thread Ian Lance Taylor 
On Fri, Feb 5, 2021 at 6:46 AM Fernando Meyer  wrote:

> I understand the pragmatism behind having or not features in the language
> and its standard library. But, almost all the golang projects I've worked
> with implement their own utility function to remove elements from a slice,
> sometimes with order in place, others not. Mostly always these home-brewed
> libraries ignore bounds-checking introducing runtime problems if the user
> is not careful enough.
>
> That said, when a feature becomes a ubiquitous necessity across so many
> codebases, I believe it should be considered to have a standard
> implementation.
>

This seems like a clear case for using generics, so let's wait on this
until we see whether the generics proposal is adopted and implemented.  I
think it is preferable to use a general language mechanism than to add a
special purpose function to the language.  See my notes about append at
https://www.airs.com/blog/archives/559.

Ian

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Re: [go-nuts] Re: Possible Go 2 proposal for built-in Remove method for Slices.

2021-02-05 Thread Fernando Meyer 
I understand the pragmatism behind having or not features in the language and 
its standard library. But, almost all the golang projects I've worked with 
implement their own utility function to remove elements from a slice, sometimes 
with order in place, others not. Mostly always these home-brewed libraries 
ignore bounds-checking introducing runtime problems if the user is not careful 
enough. 

That said, when a feature becomes a ubiquitous necessity across so many 
codebases, I believe it should be considered to have a standard implementation.

[]s
--
  Fernando Meyer
 


On Fri, Feb 5, 2021, at 2:44 PM, Matthew Holiday wrote:
> See also this graphical cheat sheet: 
> https://ueokande.github.io/go-slice-tricks/
> 
> On Fri, Feb 5, 2021 at 2:09 AM Brian Candler  wrote:
>> See: https://github.com/golang/go/wiki/SliceTricks#delete
>> (and lots of other neat tricks there).
>> 
>> There's no need to add new syntax or functions when the existing ones do the 
>> job.
>> 
>> On Thursday, 4 February 2021 at 23:55:36 UTC selahad...@gmail.com wrote:
>>> Hi,
>>> I wonder if there are any proposals for the Remove method for Slices, which 
>>> removes an element from a Slice. 
>>>  
>>> Since the status of the latest generics draft is `likely accepted` and it'd 
>>> be possible to implement this with `generics`. I believe such an addition 
>>> to language would alleviate the need to `loop + swap + resize` each time, 
>>> and enhance the overall readability since there is a consensus.
>>> 
>>> This may seem trivial, but I want to highlight some examples from other 
>>> langs just to further* *concretize:
>>> arraylist.remove(object o) => java
>>> list.remove(val) => python
>>> array.remove(at: 0) => swift 
>>> 
>>> I have looked for the proposals for Go 2 but couldn't find any regarding 
>>> this issue.
>>> 
>>> There are obviously more things to consider, like whether the operation 
>>> should keep the order. 
>>> 
>>> I'd be very happy with your responses to this pseudo-proposal.
>>> 
>> 

>> -- 
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>>  
>> .
> 
> 
> -- 
> *Matt Holiday*
> Senior Gopher, Marketing Technologies
> 
> 

> 620 Eighth Avenue

> New York, NY 10018

> matthew.holi...@nytimes.com

> 

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>  
> .

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Re: [go-nuts] Re: Possible Go 2 proposal for built-in Remove method for Slices.

2021-02-05 Thread Matthew Holiday 
See also this graphical cheat sheet:
https://ueokande.github.io/go-slice-tricks/

On Fri, Feb 5, 2021 at 2:09 AM Brian Candler  wrote:

> See: https://github.com/golang/go/wiki/SliceTricks#delete
> (and lots of other neat tricks there).
>
> There's no need to add new syntax or functions when the existing ones do
> the job.
>
> On Thursday, 4 February 2021 at 23:55:36 UTC selahad...@gmail.com wrote:
>
>> Hi,
>> I wonder if there are any proposals for the Remove method for Slices,
>> which removes an element from a Slice.
>>
>> Since the status of the latest generics draft is `likely accepted` and
>> it'd be possible to implement this with `generics`. I believe such an
>> addition to language would alleviate the need to `loop + swap + resize`
>> each time, and enhance the overall readability since there is a consensus.
>>
>> This may seem trivial, but I want to highlight some examples from other
>> langs just to further* concretize*:
>> arraylist.remove(object o) => java
>> list.remove(val) => python
>> array.remove(at: 0) => swift
>>
>> I have looked for the proposals for Go 2 but couldn't find any regarding
>> this issue.
>>
>> There are obviously more things to consider, like whether the operation
>> should keep the order.
>>
>> I'd be very happy with your responses to this pseudo-proposal.
>>
>> --
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> 
> .
>


-- 
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Senior Gopher, Marketing Technologies

620 Eighth Avenue

New York, NY 10018

matthew.holi...@nytimes.com

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[go-nuts] Re: Possible Go 2 proposal for built-in Remove method for Slices.

2021-02-05 Thread Brian Candler 
See: https://github.com/golang/go/wiki/SliceTricks#delete
(and lots of other neat tricks there).

There's no need to add new syntax or functions when the existing ones do 
the job.

On Thursday, 4 February 2021 at 23:55:36 UTC selahad...@gmail.com wrote:

> Hi,
> I wonder if there are any proposals for the Remove method for Slices, 
> which removes an element from a Slice. 
>  
> Since the status of the latest generics draft is `likely accepted` and 
> it'd be possible to implement this with `generics`. I believe such an 
> addition to language would alleviate the need to `loop + swap + resize` 
> each time, and enhance the overall readability since there is a consensus.
>
> This may seem trivial, but I want to highlight some examples from other 
> langs just to further* concretize*:
> arraylist.remove(object o) => java
> list.remove(val) => python
> array.remove(at: 0) => swift 
>
> I have looked for the proposals for Go 2 but couldn't find any regarding 
> this issue.
>
> There are obviously more things to consider, like whether the operation 
> should keep the order. 
>
> I'd be very happy with your responses to this pseudo-proposal.
>
>

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Re: [go-nuts] Re: Possible Go 2 proposal for built-in Remove method for Slices.

2021-02-04 Thread Tyler Compton 
You could imagine a `slices` standard library package that has a regular
generic function called `slices.Remove` that removes one or a series of
elements. This seems like a smart addition to me, as the current de-facto
method isn't very expressive. I imagine this didn't exist before
because adding a new built-in function has a far higher cost than adding a
simple utility function to a package.

On Thu, Feb 4, 2021 at 4:48 PM Uli Kunitz  wrote:

> Hi,
>
> You can always do a = append(a[:3], a[4:]...).  If you want to remove 2
> elements a = append(a[3:], a[:5]). You would need to call remove two
> times, which is slower and cumbersome.
>
> I have rather have two functions like copy and append than a dozen that I
> have to learn. One of the Go Proverbs is "The bigger the interface the
> weaker the abstraction."
>
> Greetings, Uli
> On Friday, February 5, 2021 at 12:55:36 AM UTC+1 selahad...@gmail.com
> wrote:
>
>> Hi,
>> I wonder if there are any proposals for the Remove method for Slices,
>> which removes an element from a Slice.
>>
>> Since the status of the latest generics draft is `likely accepted` and
>> it'd be possible to implement this with `generics`. I believe such an
>> addition to language would alleviate the need to `loop + swap + resize`
>> each time, and enhance the overall readability since there is a consensus.
>>
>> This may seem trivial, but I want to highlight some examples from other
>> langs just to further* concretize*:
>> arraylist.remove(object o) => java
>> list.remove(val) => python
>> array.remove(at: 0) => swift
>>
>> I have looked for the proposals for Go 2 but couldn't find any regarding
>> this issue.
>>
>> There are obviously more things to consider, like whether the operation
>> should keep the order.
>>
>> I'd be very happy with your responses to this pseudo-proposal.
>>
>> --
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> 
> .
>

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[go-nuts] Re: Possible Go 2 proposal for built-in Remove method for Slices.

2021-02-04 Thread Uli Kunitz 
Hi,

You can always do a = append(a[:3], a[4:]...).  If you want to remove 2 
elements a = append(a[3:], a[:5]). You would need to call remove two 
times, which is slower and cumbersome.

I have rather have two functions like copy and append than a dozen that I 
have to learn. One of the Go Proverbs is "The bigger the interface the 
weaker the abstraction."

Greetings, Uli
On Friday, February 5, 2021 at 12:55:36 AM UTC+1 selahad...@gmail.com wrote:

> Hi,
> I wonder if there are any proposals for the Remove method for Slices, 
> which removes an element from a Slice. 
>  
> Since the status of the latest generics draft is `likely accepted` and 
> it'd be possible to implement this with `generics`. I believe such an 
> addition to language would alleviate the need to `loop + swap + resize` 
> each time, and enhance the overall readability since there is a consensus.
>
> This may seem trivial, but I want to highlight some examples from other 
> langs just to further* concretize*:
> arraylist.remove(object o) => java
> list.remove(val) => python
> array.remove(at: 0) => swift 
>
> I have looked for the proposals for Go 2 but couldn't find any regarding 
> this issue.
>
> There are obviously more things to consider, like whether the operation 
> should keep the order. 
>
> I'd be very happy with your responses to this pseudo-proposal.
>
>

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