[swift-users] Flatmap initializer inconsistency
owenzx at gmail.com
Mon May 1 22:48:37 CDT 2017
That is because for `Optional` the `flatMap` is `func flatMap<U>(_
transform: (Wrapped) throws -> U?) rethrows -> U?` and for `Int`, only
`init?(exactly value: Double)` fits the situation. `init(_ value: Double)`
doesn't return nil. So there is no ambiguity.
On Tue, May 2, 2017 at 4:20 AM, Saagar Jha <saagar at saagarjha.com> wrote:
> Well, the question still remains about why the compiler chose
> init(exactly:) over init(). Shouldn’t there at least a warning of ambiguity?
> Saagar Jha
> On May 1, 2017, at 12:11, Zhao Xin via swift-users <swift-users at swift.org>
> In my test, compiler thought you use `init?(exactly value: Double)`, which
> returns nil. So this is not a bug.
> On Tue, May 2, 2017 at 1:39 AM, Halen Wooten via swift-users <
> swift-users at swift.org> wrote:
>> I'm seeing a weird issue with using an initializer in flatMap. Here's
>> an example:
>> let time: TimeInterval? = 662.82582598600004
>> let intTimeFlatmap = time.flatMap(Int.init) // nil
>> let intTime = Int(time!) // 662
>> I would expect for the flatMap call to return an optional Int with the
>> proper value of 662. Is there something I'm misunderstanding, or is
>> this a swift bug?
>> swift-users mailing list
>> swift-users at swift.org
> swift-users mailing list
> swift-users at swift.org
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