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

[Jeremy Pereira]

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

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


> 
> On Tue, Jan 5, 2016 at 1:01 PM, Jeremy Pereira <jeremy.j.pereira at googlemail.com> wrote:
> 
> > On 5 Jan 2016, at 12:51, James Campbell <james at supmenow.com> 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 <jeremy.j.pereira at 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 at swift.org> wrote:
> > >
> > > See this code:
> > > var distanceCache: [Int: Int] = Dictionary<Int, Int>()
> > >
> > > 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
> > > james at supmenow.com
> > > +44 7523 279 698
> > >  _______________________________________________
> > > swift-evolution mailing list
> > > swift-evolution at swift.org
> > > https://lists.swift.org/mailman/listinfo/swift-evolution
> >
> >
> >
> >
> > --
> >  Wizard
> > james at supmenow.com
> > +44 7523 279 698
> 
> 
> 
> 
> -- 
>  Wizard
> james at supmenow.com
> +44 7523 279 698