Re: [swift-evolution] Be able to initialise empty dict with array constrcutor

[Alexander Kempgen via swift-evolution]

Yes. All of these variants are covered in the book The Swift Programming 
Language in some detail.

Alex

–
Alexander Kempgen
a...@kempgen.de

> Am 05.01.2016 um 14:42 schrieb James Campbell via swift-evolution 
> :
> 
> So the [Int]() is shorthand for Array()
> 
> On Tue, Jan 5, 2016 at 1:01 PM, Jeremy Pereira 
> > 
> wrote:
> 
> > On 5 Jan 2016, at 12:51, James Campbell  > > wrote:
> >
> > The problem for me is that is so counter intuitive I didn't even know you 
> > could do that.
> 
> The first one is a bit counter intuitive and I agree that
> 
> var distanceCache: [Int: Int] = []
> 
> might be an improvement, albeit not one I think many people would agree is 
> worth doing. However, the second one is a natural extrapolation from the 
> equivalent array syntax i.e.
> 
> var array = [Int]()
> var dictionary = [String: Int]()
> 
> >
> > On Tue, Jan 5, 2016 at 12:50 PM, Jeremy Pereira 
> > > 
> > wrote:
> > I don’t understand what the problem is
> >
> > > On 5 Jan 2016, at 12:39, James Campbell via swift-evolution 
> > > > wrote:
> > >
> > > See this code:
> > > var distanceCache: [Int: Int] = Dictionary()
> > >
> > > It is very long and tedious to write especially if what I am storing 
> > > changes.
> > >
> > > I propose we be allowed to do the following:
> > > var distanceCache: [Int: Int] = []
> >
> > You can do
> >
> > var distanceCache: [Int: Int] = [:]
> >
> > Also
> >
> > var distanceCache2 = [Int: Int]()
> >
> >
> > > Perhaps this dictionary syntax is just confusing and it was a bad idea to 
> > > make it the same as an array. Most languages use "{" so why did swift 
> > > choose to share "[" with arrays and dictionaries.
> >
> > It’s not the same, you need the colons inside. I imagine that braces were 
> > discarded on the grounds that it would confuse the compiler with respect to 
> > closures, for example
> >
> > var myClosure = {} // is a variable of type () -> ()
> >
> >
> > >
> > > --
> > >  Wizard
> > > ja...@supmenow.com 
> > > +44 7523 279 698 
> > >  ___
> > > swift-evolution mailing list
> > > swift-evolution@swift.org 
> > > https://lists.swift.org/mailman/listinfo/swift-evolution 
> > > 
> >
> >
> >
> >
> > --
> >  Wizard
> > ja...@supmenow.com 
> > +44 7523 279 698 
> 
> 
> 
> 
> -- 
>  Wizard
> ja...@supmenow.com 
> +44 7523 279 698
>  ___
> swift-evolution mailing list
> swift-evolution@swift.org 
> https://lists.swift.org/mailman/listinfo/swift-evolution 
> 
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Re: [swift-evolution] Be able to initialise empty dict with array constrcutor

[Jeremy Pereira via swift-evolution]

> On 5 Jan 2016, at 13:42, James Campbell  wrote:
> 
> So the [Int]() is shorthand for Array()

Yes. In general, you can write [T] anywhere you can write Array and [U : V] 
anywhere you can write Dictionary. The are both syntactic sugar.


> 
> On Tue, Jan 5, 2016 at 1:01 PM, Jeremy Pereira 
>  wrote:
> 
> > On 5 Jan 2016, at 12:51, James Campbell  wrote:
> >
> > The problem for me is that is so counter intuitive I didn't even know you 
> > could do that.
> 
> The first one is a bit counter intuitive and I agree that
> 
> var distanceCache: [Int: Int] = []
> 
> might be an improvement, albeit not one I think many people would agree is 
> worth doing. However, the second one is a natural extrapolation from the 
> equivalent array syntax i.e.
> 
> var array = [Int]()
> var dictionary = [String: Int]()
> 
> >
> > On Tue, Jan 5, 2016 at 12:50 PM, Jeremy Pereira 
> >  wrote:
> > I don’t understand what the problem is
> >
> > > On 5 Jan 2016, at 12:39, James Campbell via swift-evolution 
> > >  wrote:
> > >
> > > See this code:
> > > var distanceCache: [Int: Int] = Dictionary()
> > >
> > > It is very long and tedious to write especially if what I am storing 
> > > changes.
> > >
> > > I propose we be allowed to do the following:
> > > var distanceCache: [Int: Int] = []
> >
> > You can do
> >
> > var distanceCache: [Int: Int] = [:]
> >
> > Also
> >
> > var distanceCache2 = [Int: Int]()
> >
> >
> > > Perhaps this dictionary syntax is just confusing and it was a bad idea to 
> > > make it the same as an array. Most languages use "{" so why did swift 
> > > choose to share "[" with arrays and dictionaries.
> >
> > It’s not the same, you need the colons inside. I imagine that braces were 
> > discarded on the grounds that it would confuse the compiler with respect to 
> > closures, for example
> >
> > var myClosure = {} // is a variable of type () -> ()
> >
> >
> > >
> > > --
> > >  Wizard
> > > ja...@supmenow.com
> > > +44 7523 279 698
> > >  ___
> > > swift-evolution mailing list
> > > swift-evolution@swift.org
> > > https://lists.swift.org/mailman/listinfo/swift-evolution
> >
> >
> >
> >
> > --
> >  Wizard
> > ja...@supmenow.com
> > +44 7523 279 698
> 
> 
> 
> 
> -- 
>  Wizard
> ja...@supmenow.com
> +44 7523 279 698

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Re: [swift-evolution] Be able to initialise empty dict with array constrcutor

[James Campbell via swift-evolution]

Thats a small but huge improvement :)

On Tue, Jan 5, 2016 at 6:58 PM, Chris Lattner  wrote:

> You’re completely right, but we don’t need to change the swift language to
> fix that.  As of 3f19714, which I just pushed, we now emit this error
> message (which includes a fixit hint to insert the colon):
>
> t.swift:2:33: error: use [:] to get an empty dictionary literal
> var distanceCache: [Int: Int] = []
> ^
>  :
>
> instead of:
>
> t.swift:2:33: error: contextual type '[Int : Int]' cannot be used with
> array literal
> var distanceCache: [Int: Int] = []
> ^~
>
> That should address the problem, thanks for pointing this out!
>
> -Chris
>
> On Jan 5, 2016, at 4:51 AM, James Campbell via swift-evolution <
> swift-evolution@swift.org> wrote:
>
> The problem for me is that is so counter intuitive I didn't even know you
> could do that.
>
> On Tue, Jan 5, 2016 at 12:50 PM, Jeremy Pereira <
> jeremy.j.pere...@googlemail.com> wrote:
>
>> I don’t understand what the problem is
>>
>> > On 5 Jan 2016, at 12:39, James Campbell via swift-evolution <
>> swift-evolution@swift.org> wrote:
>> >
>> > See this code:
>> > var distanceCache: [Int: Int] = Dictionary()
>> >
>> > It is very long and tedious to write especially if what I am storing
>> changes.
>> >
>> > I propose we be allowed to do the following:
>> > var distanceCache: [Int: Int] = []
>>
>> You can do
>>
>> var distanceCache: [Int: Int] = [:]
>>
>> Also
>>
>> var distanceCache2 = [Int: Int]()
>>
>>
>> > Perhaps this dictionary syntax is just confusing and it was a bad idea
>> to make it the same as an array. Most languages use "{" so why did swift
>> choose to share "[" with arrays and dictionaries.
>>
>> It’s not the same, you need the colons inside. I imagine that braces were
>> discarded on the grounds that it would confuse the compiler with respect to
>> closures, for example
>>
>> var myClosure = {} // is a variable of type () -> ()
>>
>>
>> >
>> > --
>> >  Wizard
>> > ja...@supmenow.com
>> > +44 7523 279 698
>> >  ___
>> > swift-evolution mailing list
>> > swift-evolution@swift.org
>> > https://lists.swift.org/mailman/listinfo/swift-evolution
>>
>>
>
>
> --
>  Wizard
> ja...@supmenow.com
> +44 7523 279 698
>  ___
> swift-evolution mailing list
> swift-evolution@swift.org
> https://lists.swift.org/mailman/listinfo/swift-evolution
>
>
>


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Re: [swift-evolution] Be able to initialise empty dict with array constrcutor

[James Campbell via swift-evolution]

Perhaps instead of "auto" we could allow "lazy" to create a default lazy
constructor for these cases ?

On Tue, Jan 5, 2016 at 12:39 PM, James Campbell  wrote:

> See this code:
>
> var distanceCache: [Int: Int] = Dictionary()
> It is very long and tedious to write especially if what I am storing
> changes.
>
> I propose we be allowed to do the following:
>
> *var distanceCache: [Int: Int] = []*
>
> If this isn't possible then I wouldn't mind having some way of telling the
> compiler to auto create it like so:
>
> *var distanceCache: [Int: Int] ()*
>
> or
>
> *var distanceCache: [Int: Int] = new Dictionary*
>
> or even:
>
> *var distanceCache: [Int: Int] = auto*
>
> *auto var distanceCache: [Int: Int]*
>
> (auto short for auto create)
>
>
> Perhaps this dictionary syntax is just confusing and it was a bad idea to
> make it the same as an array. Most languages use "{" so why did swift
> choose to share "[" with arrays and dictionaries.
> --
>  Wizard
> ja...@supmenow.com
> +44 7523 279 698
>



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Re: [swift-evolution] Be able to initialise empty dict with array constrcutor

[Jeremy Pereira via swift-evolution]

I don’t understand what the problem is

> On 5 Jan 2016, at 12:39, James Campbell via swift-evolution 
>  wrote:
> 
> See this code:
> var distanceCache: [Int: Int] = Dictionary()
> 
> It is very long and tedious to write especially if what I am storing changes.
> 
> I propose we be allowed to do the following:
> var distanceCache: [Int: Int] = []

You can do 

var distanceCache: [Int: Int] = [:]

Also

var distanceCache2 = [Int: Int]()


> Perhaps this dictionary syntax is just confusing and it was a bad idea to 
> make it the same as an array. Most languages use "{" so why did swift choose 
> to share "[" with arrays and dictionaries.

It’s not the same, you need the colons inside. I imagine that braces were 
discarded on the grounds that it would confuse the compiler with respect to 
closures, for example

var myClosure = {} // is a variable of type () -> ()


> 
> -- 
>  Wizard
> ja...@supmenow.com
> +44 7523 279 698
>  ___
> swift-evolution mailing list
> swift-evolution@swift.org
> https://lists.swift.org/mailman/listinfo/swift-evolution

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[swift-evolution] Be able to initialise empty dict with array constrcutor

[James Campbell via swift-evolution]

See this code:

var distanceCache: [Int: Int] = Dictionary()
It is very long and tedious to write especially if what I am storing
changes.

I propose we be allowed to do the following:

*var distanceCache: [Int: Int] = []*

If this isn't possible then I wouldn't mind having some way of telling the
compiler to auto create it like so:

*var distanceCache: [Int: Int] ()*

or

*var distanceCache: [Int: Int] = new Dictionary*

or even:

*var distanceCache: [Int: Int] = auto*

*auto var distanceCache: [Int: Int]*

(auto short for auto create)


Perhaps this dictionary syntax is just confusing and it was a bad idea to
make it the same as an array. Most languages use "{" so why did swift
choose to share "[" with arrays and dictionaries.
-- 
 Wizard
ja...@supmenow.com
+44 7523 279 698
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Re: [swift-evolution] Be able to initialise empty dict with array constrcutor

[James Campbell via swift-evolution]

The problem for me is that is so counter intuitive I didn't even know you
could do that.

On Tue, Jan 5, 2016 at 12:50 PM, Jeremy Pereira <
jeremy.j.pere...@googlemail.com> wrote:

> I don’t understand what the problem is
>
> > On 5 Jan 2016, at 12:39, James Campbell via swift-evolution <
> swift-evolution@swift.org> wrote:
> >
> > See this code:
> > var distanceCache: [Int: Int] = Dictionary()
> >
> > It is very long and tedious to write especially if what I am storing
> changes.
> >
> > I propose we be allowed to do the following:
> > var distanceCache: [Int: Int] = []
>
> You can do
>
> var distanceCache: [Int: Int] = [:]
>
> Also
>
> var distanceCache2 = [Int: Int]()
>
>
> > Perhaps this dictionary syntax is just confusing and it was a bad idea
> to make it the same as an array. Most languages use "{" so why did swift
> choose to share "[" with arrays and dictionaries.
>
> It’s not the same, you need the colons inside. I imagine that braces were
> discarded on the grounds that it would confuse the compiler with respect to
> closures, for example
>
> var myClosure = {} // is a variable of type () -> ()
>
>
> >
> > --
> >  Wizard
> > ja...@supmenow.com
> > +44 7523 279 698
> >  ___
> > swift-evolution mailing list
> > swift-evolution@swift.org
> > https://lists.swift.org/mailman/listinfo/swift-evolution
>
>


-- 
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ja...@supmenow.com
+44 7523 279 698
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