[swift-evolution] Feature proposal: Range operator with step

David Knothe dknothe314 at me.com
Thu Mar 24 02:34:27 CDT 2016

I see your point that a simple extension on ranges and similar types would also do the thing.

But I do think that this is not as easy as many users would expect.
For example, I try to avoid parentheses in for loops as much as I can, but in your example, 4 additional brackets are required. A simple keyword („step" or „by“) would solve the problem seamlessly.

Also, a new template could be introduced that shows the existence of the new keyword:

I think adding such a new keyword would improve the ease and the clearness of the Swift language more than just adding some protocol extensions.

> Am 24.03.2016 um 00:02 schrieb Haravikk <swift-evolution at haravikk.me>:
> I’m behind the idea in principle, but I’m not so sure we need a new keyword for this:
> 	for eachIndex in (1 ..< 10).by(2) { … }
> The above would be adequate I thin, and just requires a new method on ranges and similar types. This is being discussed, among other things, in the c-style for loop discussion, as these were recently removed but without a replacement for this type of use-case.
>> On 23 Mar 2016, at 21:40, David Knothe via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
>> Hi,
>> I am new to Swift mailing list so I don’t know if this topic has already been discussed.
>> I like Swift's range operators ..< and …
>> What I am missing though is an easy operator to create a range with a specified step. Currently, if you would want to iterate over some odd numbers, you had to write:
>> for i in 1.stride(through: 7, by: 2) { … }
>> What I think would be simpler and more convenient would be something like the following:
>> for i in 1 … 7 step 2 { … } . Another option would be  for i in 1 … 7; 2 { … }
>> The keyword ‚step‘ in this context clearly corresponds to the step of the range to create or to iterate over.
>> Essentially this is a syntactic sugar that makes it easy to create ranges with a step ≠ 1. What do you think?
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