[swift-evolution] Switch on an optional enum -- `case: nil`?

Krzysztof Siejkowski krzysztof at siejkowski.net
Thu May 5 10:52:24 CDT 2016

It doesn’t compile because you’re switching on the Optional and trying to pattern match it to Coin.

It compiles right when you pattern match it to Optional<Coin>:

switch result {
case .heads?: print("heads")
case .tails?: print("tails")
case nil: print("not yet flipped")


On 5 May 2016 at 17:42:24, Eric Miller via swift-evolution (swift-evolution at swift.org) wrote:

Wondering if you guys think this is a reasonable idea.

I was switching on an optional enum today, and naturally gravitated towards including nil as a case:

enum Coin {
  case heads
  case tails
var result: Coin?

switch result {
case heads: print("heads")
case tails: print("tails")
case nil: print("not yet flipped") // exhaustive

Doesn't compile, and of course I can if-let or guard to unwrap instead, but I like the compactness of this.
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