Safely index items within a collection

We can make some great things with extensions in Swift, as well as subscript functions. This one allows us to safely access collection elements by index, getting back an optional instead of errors being thrown!

extension Collection {
    subscript(safe index: Index) -> Element? {
        indices.contains(index) ? self[index] : nil
    }
}

let numbers = [1, 2, 3, 4]
numbers[safe: 3] // 4
numbers[safe: 10] // nil, no error

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Thanks for reading!