The shorthands mystify me as well. I have taught a few courses using Swift and the shorthand notation, as well as implicit variables like oldValue and newValue

The shorthands mystify me as well. I have taught a few courses using Swift and the shorthand notation, as well as implicit variables like oldValue and newValue in setters, are confusing. You can try to ignore them, but eventually a student will find them. In my experience, teaching courses using Racket have had better outcomes. At the end of the Racket courses, I can quickly transition students to other languages, including Swift. It hasn't worked out so well with Swift. I am still gathering data so I can come to a better conclusion as to why.