[swift-evolution] 100% bikeshed topic: DictionaryLiteral

[Ben Cohen]

> On Jan 8, 2018, at 5:08 PM, Karl Wagner <razielim at gmail.com> wrote:
> 
> 
> 
>> On 9. Jan 2018, at 01:29, Ben Cohen via swift-evolution <swift-evolution at swift.org> wrote:
>> 
>> There exists in the standard library a type `DictionaryLiteral` that deserves naming re-consideration before we declare ABI Stability, because it’s confusingly misnamed, being neither a Dictionary (it doesn’t provide key-based lookup of values) nor a Literal. 
>> 
>> Instead, it’s just an immutable collection of key-value pairs you can create _from_ a literal.
>> 
>> I’m canvassing for opinions on what it ought to be called.  Some suggestions so far:
>> 
>> - `AssociationCollection`: Following the term of art from some other languages. Slightly obscure-sounding to developers not already familiar. Also “association” and “associative” are confusingly similar, which brings back the is-this-a-dictionary problem.
>> - `KeyValueCollection`: Problematic because key-value comes up in a totally different context in Cocoa.
>> - `PairCollection`: “Pair” is kinda nondescript.
>> - Do nothing. It’s not so bad.
>> 
>> The old name can live on indefinitely via a typealias (which has no ABI consequences, so could be retired at a later date once everyone has had plenty of time to address the deprecation warnings). Removing it as not carrying its weight (and instead using `[(Key,Value)]`, which is basically what it’s a wrapper for) is probably off the table for source stability reasons.
>> 
>> Any further thoughts welcome.
>> 
>> 
>> 
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> 
> 
> Since it is a generic type, could it not be nested inside of the appropriate Dictionary<Key, Value> type? That would make 2 or 3 more reasonable.
> 
> Also, what about Dictionary<Key, Value>.KeyValuePairs?
> 
> - Karl

It’s really not related to the Dictionary type. This isn’t part of Dictionary’s implementation leaking out, like DictionaryIndex or DictionaryIterator were. It’s a separate independently (marginally-) useful type.