NumberFormatterRanges

The following tweet from Daniel Steinberg got me thinking about the number formatter API.

I mostly use the number formatter to set the fractional digits like this:

f.minimumFractionDigits = 3

f.maximumFractionDigits = 3

why no f.fractionDigits computed property in the Swift overlay

I know - not important in the scheme of all that is wrong in the world.

You could replace these two properties with one based on a ClosedRange<Int> instead:

extension NumberFormatter {

    public var fractionDigits: ClosedRange<Int> {
        set {
            minimumFractionDigits = newValue.lowerBound
            maximumFractionDigits = newValue.upperBound
        }
        get {
            ClosedRange(uncheckedBounds: (minimumFractionDigits, maximumFractionDigits))
        }
    }
}

This would allow you to set both in one line like so: f.fractionDigits = 3...3

However if ClosedRange<Int> where to also gain conformance to ExpressibleByIntegerLiteral

extension ClosedRange: ExpressibleByIntegerLiteral where Bound == Int {

    public init(integerLiteral value: Int) {
        self = value...value
    }
}

then you could also do f.fractionDigits = 3 providing a single property to set the minimum and maximum or just a single value. It also removes the bounds checking out from NumberFormatter and using the existing checks in ClosedRange itself.