PartialRangeThrough

You create PartialRangeThrough instances by using the prefix closed range operator (prefix ...).

let throughFive = ...5.0

You can use a PartialRangeThrough instance to quickly check if a value is contained in a particular range of values. For example:

throughFive.contains(4.0)     // true
throughFive.contains(5.0)     // true
throughFive.contains(6.0)     // false

You can use a PartialRangeThrough instance of a collection’s indices to represent the range from the start of the collection up to, and including, the partial range’s upper bound.

let numbers = [10, 20, 30, 40, 50, 60, 70]
print(numbers[...3])
// Prints "[10, 20, 30, 40]"