Re: Add an easier method for slicing and stepping strings and arrays

[Isiah Meadows]

To clarify, I'm just a normal, non-committee person. So that's a "I like
the idea and it looks workable", but not "I'll champion this for you" (when
I can't).

On Wed, Jul 26, 2017, 21:41 Isiah Meadows  wrote:

> That, I could support.
>
> On Wed, Jul 26, 2017, 16:38 Alexander Craggs 
> wrote:
>
>> In which case,  perhaps change this proposal to .slice(start, end, step)
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Re: Add an easier method for slicing and stepping strings and arrays

[Isiah Meadows]

That, I could support.

On Wed, Jul 26, 2017, 16:38 Alexander Craggs 
wrote:

> In which case,  perhaps change this proposal to .slice(start, end, step)
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Re: Add an easier method for slicing and stepping strings and arrays

[Alexander Craggs]

In which case,  perhaps change this proposal to .slice(start, end, step)___
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Re: Re: Add an easier method for slicing and stepping strings and arrays

[Jordan Harband]

Array slice already allows negative indexes. `arr.slice(-1)[0]` works fine
for a quick and dirty "last item".

On Mon, Jul 24, 2017 at 3:19 PM, Tab Atkins Jr. 
wrote:

> On Sun, Jul 23, 2017 at 12:36 AM, Darien Valentine
>  wrote:
> > Here are some related threads from the past:
> >
> > https://esdiscuss.org/topic/negative-indices-for-arrays
> > https://esdiscuss.org/topic/array-slice-syntax
> > https://esdiscuss.org/topic/javascript-language-feature-idea
> >
> > I think I’ve seen it mentioned a few other times too.
> >
> > The `arr[-1]` syntax is a non-starter I’m afraid, cause it’s just
> property
> > access. An array can already have a property with the key "-1".
> >
> > Personally I’d find it weird for slicing to be singled out for special
> > syntax. It’s just a method. However I’d agree that it’s quite awkward to
> do
> > things like `arr[arr.length - 1]` or `arr.slice().pop()` etc to access
> from
> > the right. I think in one of those threads someone proposed a method like
> > `Array.prototype.nth()` which would accept negative indices, though this
> > creates an odd asymmetry since (presumably) we would not want to use -0
> for
> > the last index.
>
> Yeah, -1 is the last index; it just does one round of "underflow"
> basically.
>
> > In general I think the functionality you’re describing could be useful
> but
> > that it could be served better by adding methods rather than syntax.
>
> Agreed. Slicing via Array#slice() can likely be extended to allow
> negative indexes, and even a third argument for steps to match Python
> (yay for the -1 step value, to get a slice in reverse!).  Adding an
> nth() that just takes a single positive or negative index would be
> nice.  That we still have to do `arr[arr.length -1]` is barbaric. ^_^
>
> (Only downside of negative indexes is that, when using it on
> iterators, you have to consume the entire iterator before you can
> return the desired value.)
>
> ~TJ
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Re: Re: Add an easier method for slicing and stepping strings and arrays

[Tab Atkins Jr.]

On Sun, Jul 23, 2017 at 12:36 AM, Darien Valentine
 wrote:
> Here are some related threads from the past:
>
> https://esdiscuss.org/topic/negative-indices-for-arrays
> https://esdiscuss.org/topic/array-slice-syntax
> https://esdiscuss.org/topic/javascript-language-feature-idea
>
> I think I’ve seen it mentioned a few other times too.
>
> The `arr[-1]` syntax is a non-starter I’m afraid, cause it’s just property
> access. An array can already have a property with the key "-1".
>
> Personally I’d find it weird for slicing to be singled out for special
> syntax. It’s just a method. However I’d agree that it’s quite awkward to do
> things like `arr[arr.length - 1]` or `arr.slice().pop()` etc to access from
> the right. I think in one of those threads someone proposed a method like
> `Array.prototype.nth()` which would accept negative indices, though this
> creates an odd asymmetry since (presumably) we would not want to use -0 for
> the last index.

Yeah, -1 is the last index; it just does one round of "underflow" basically.

> In general I think the functionality you’re describing could be useful but
> that it could be served better by adding methods rather than syntax.

Agreed. Slicing via Array#slice() can likely be extended to allow
negative indexes, and even a third argument for steps to match Python
(yay for the -1 step value, to get a slice in reverse!).  Adding an
nth() that just takes a single positive or negative index would be
nice.  That we still have to do `arr[arr.length -1]` is barbaric. ^_^

(Only downside of negative indexes is that, when using it on
iterators, you have to consume the entire iterator before you can
return the desired value.)

~TJ
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Re: Re: Add an easier method for slicing and stepping strings and arrays

[Dante Federici]

This feels like an attempt to get toward python's style of slice
. Which
I'm not opposed to, and would like to hear how it's better than just the
method.
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Re: Re: Add an easier method for slicing and stepping strings and arrays

[Darien Valentine]

Here are some related threads from the past:

https://esdiscuss.org/topic/negative-indices-for-arrays
https://esdiscuss.org/topic/array-slice-syntax
https://esdiscuss.org/topic/javascript-language-feature-idea

I think I’ve seen it mentioned a few other times too.

The `arr[-1]` syntax is a non-starter I’m afraid, cause it’s just property
access. An array can already have a property with the key "-1".

Personally I’d find it weird for slicing to be singled out for special
syntax. It’s just a method. However I’d agree that it’s quite awkward to do
things like `arr[arr.length - 1]` or `arr.slice().pop()` etc to access from
the right. I think in one of those threads someone proposed a method like
`Array.prototype.nth()` which would accept negative indices, though this
creates an odd asymmetry since (presumably) we would not want to use -0 for
the last index.

In general I think the functionality you’re describing could be useful but
that it could be served better by adding methods rather than syntax.
___
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