[swift-evolution] [SE-0011] Re-considering the replacement keyword for "typealias"

[Stephen Celis]

> On Dec 19, 2015, at 11:14 PM, Dave Abrahams via swift-evolution <swift-evolution at swift.org> wrote:
> 
>> On Dec 19, 2015, at 5:09 PM, Brent Royal-Gordon via swift-evolution <swift-evolution at swift.org> 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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