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One-sided ranges

Available from Swift 4.0

Paul Hudson      @twostraws

Last but not least, Swift 4 introduced Python-like one-sided collection slicing, where the missing side is automatically inferred to be the start or end of the collection. This has no effect on existing code because it's a new use for the existing operator, so you don't need to worry about potential breakage.

Here's an example:

let characters = ["Dr Horrible", "Captain Hammer", "Penny", "Bad Horse", "Moist"]
let bigParts = characters[..<3]
let smallParts = characters[3...]
print(bigParts)
print(smallParts)

That code will print out ["Dr Horrible", "Captain Hammer", "Penny"] then ["Bad Horse", "Moist"].

For more information see the Swift Evolution proposal for this new feature.

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Other changes in Swift 4.0…

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