> On Dec 19, 2015, at 11:14 PM, Dave Abrahams via swift-evolution
> <[email protected]> wrote:
>
>> On Dec 19, 2015, at 5:09 PM, Brent Royal-Gordon via swift-evolution
>> <[email protected]> wrote:
>>
>> I don't think `required` captures the intended meaning *at all*. You're not
>> required to declare the type of a "required typealias"—it's often, perhaps
>> even usually, inferred.
>
> No, but it is required to exist and can't always be inferred. It puts a
> constraint on the type that is declared to conform. This is a requirement in
> exactly the same sense that other protocol requirements are requirements.
> Notably operator requirements may be satisfied "implicitly" by declarations
> that already exist, but they are still requirements.
I think reusing "required" here (where "typealias" has already been reused)
could make the concept of associated types more opaque to new users.
The use of "typealias" as a kind of "typedef" immediately made sense to me.
When I first stumbled upon "typealias" in a protocol, it took me some time to
fully grok its use and its connection to its "typedef" counterpart.
Stephen
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