[swift-evolution] [Review] SE-0094: Add sequence(initial:next:) and sequence(state:next:) to the stdlib

[Trent Nadeau]

Ah, yes. I apologize. The fact that state is inout, and the same instance
is always passed in confused me. Thanks for the correction.

On Thu, May 19, 2016 at 7:46 PM, Brent Royal-Gordon <brent at architechies.com>
wrote:

> > Also note that there's a typo in the second example:
> >
> > for view in sequence(initial: someView, next: { $0.
> > superview }) {
> >
> > // someView, someView.superview, someView.superview.superview, ...
> >
> > }
> >
> >
> > should be:
> >
> > for view in sequence(state: someView, next: { $0.
> > superview }) {
> >
> > // someView, someView.superview, someView.superview.superview, ...
> >
> > }
>
> I don't think these are mistakes—in each iteration of the loop, $0 is
> supposed to be the view from the previous iteration.
>
> If you wanted an example using `state`, here's one which is roughly
> equivalent to `stride(from: 1.0, to: 2.0, by: 0.1)`, using a
> non-error-accumulating algorithm:
>
>         let start = 1.0
>         let end = 2.0
>         let distance = 0.1
>
>         for color in sequence(state: -1.0, next: { $0 += 1; let next =
> start + $0 * distance; return next < end ? next : nil }) {
>                 …
>         }
>
> --
> Brent Royal-Gordon
> Architechies
>
>


-- 
Trent Nadeau
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