It would be very convenient if Decimal128 had options for string formatting - it could then for example, more easily be used for currency. Similar to how a Double can be formatted

As is, Swift Doubles have this feature:

 let myDouble = 1999.95
 let currencyFormatted = myDouble.formatted(.currency(code: "USD"))
 print(currencyFormatted)

and the output is

 $1,999.95

My suggest is to add a formatted feature to Decimal128

    let d = Decimal128(1999.95)
    let s = d.formatted(.currency(code: "USD"))