I’d like to propose we add a function to Range<T> which allows transforming its
bounds (both bounds, by the same transform). This would come in handy in many
situations involving type conversions or bounds mutations:
// duplicated on CountableRange
extension Range {
func mapRange<T: Comparable>(_ transform: (Bound) throws -> T) rethrows ->
Range<T> {
return try transform(lowerBound)..<(try transform(upperBound))
}
}
// Type conversion:
(myWrappedVal..<myOtherWrappedVal).mapRange { $0.sourceValue }
// Shifting:
(5..<15).mapRange { $0 + offset }
Is there some reason why this would not be desirable? It’s a convenience
addition, sure, but it is very convenient if you use generic code with lots of
Ranges and wrapping abstractions.
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