> On 29 Jun 2016, at 15:47, Matthew Johnson via swift-evolution
> <[email protected]> wrote:
>
>
> IIRC Optional conformed to this protocol early on and that conformance was
> removed. In practice the idea of a protocol for "truthiness" to which
> non-Boolean types conform caused more confusion than it provided value. It
> was a cool idea that just didn't work out so well.
>
> IMO if it doesn't make sense for Optional to conform it is pretty unlikely it
> would make sense for other types to conform. It seems like a good idea to
> remove the protocol.
I certainly agree that it doesn’t make much sense for Optional, but I believe
that implicit bool conformance can be a desirable feature for a number of
applications. For instance, imagine a logical inference library where you can
have entities like Term or Formula. For those, Boolean conformance would make a
lot of sense. Of course, one can also make explicit conversions e.g.:
extension Bool {
init(x: Term) { self = x.truthValue }
}
if Bool(f1) { … }
But since Bool is a syntactically privileged construct in the language, it
makes sense to have it as a target of built-in type conversion support, for the
same reason why we have CustomStringConvertible etc.
To be honest, I’d prefer to have a generic mechanism such as:
ImplicitConvertible<T> {
var as -> T { get }
}
to replace the Custom*Convertible and friends, but thats a different topic.
— Taras
>
>>
>> - Dave Sweeris
>>
>>
>> On Jun 29, 2016, at 01:44, Douglas Gregor via swift-evolution
>> <[email protected] <mailto:[email protected]>> wrote:
>>
>>> Hello Swift community,
>>>
>>> The review of SE-0109 "Remove the Boolean protocol" begins now and runs
>>> through July 4, 2016. The proposal is available here:
>>>
>>> https://github.com/apple/swift-evolution/blob/master/proposals/0109-remove-boolean.md
>>>
>>> <https://github.com/apple/swift-evolution/blob/master/proposals/0109-remove-boolean.md>
>>> Reviews are an important part of the Swift evolution process. All reviews
>>> should be sent to the swift-evolution mailing list at
>>>
>>> https://lists.swift.org/mailman/listinfo/swift-evolution
>>> <https://lists.swift.org/mailman/listinfo/swift-evolution>
>>> or, if you would like to keep your feedback private, directly to the review
>>> manager. When replying, please try to keep the proposal link at the top of
>>> the message:
>>>
>>> Proposal link:
>>>
>>> https://github.com/apple/swift-evolution/blob/master/proposals/0109-remove-boolean.md
>>>
>>> <https://github.com/apple/swift-evolution/blob/master/proposals/0109-remove-boolean.md>
>>> Reply text
>>>
>>> Other replies
>>> <https://github.com/apple/swift-evolution#what-goes-into-a-review-1>What
>>> goes into a review?
>>>
>>> The goal of the review process is to improve the proposal under review
>>> through constructive criticism and, eventually, determine the direction of
>>> Swift. When writing your review, here are some questions you might want to
>>> answer in your review:
>>>
>>> What is your evaluation of the proposal?
>>> Is the problem being addressed significant enough to warrant a change to
>>> Swift?
>>> Does this proposal fit well with the feel and direction of Swift?
>>> If you have used other languages or libraries with a similar feature, how
>>> do you feel that this proposal compares to those?
>>> How much effort did you put into your review? A glance, a quick reading, or
>>> an in-depth study?
>>> More information about the Swift evolution process is available at
>>>
>>> https://github.com/apple/swift-evolution/blob/master/process.md
>>> <https://github.com/apple/swift-evolution/blob/master/process.md>
>>> Thank you,
>>>
>>> -Doug
>>>
>>> Review Manager
>>>
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