Optional Iteration

[AnthonyLatsis]

This proposal is about allowing optional sequences in for-in loops.

var array: [Int]? = nil

for? element in array { ... } // does nothing

array = [1, 2, 3]

for? element in array { ... }
// equivalent to
for element in array! { ... }

https://forums.swift.org/t/another-try-at-allowing-optional-iteration/14376/44

Implementation – swiftlang/swift#19207

[AnthonyLatsis]

@jrose-apple, is it possible to schedule a review for this?

[jrose-apple]

I'm not on the core team, sorry. I'm not sure if they were waiting for anything else.

[AnthonyLatsis]

I see, excuse me then.

cc @jckarter

[jckarter]

I would clarify what the syntactic construct is equivalent to in the general case:

if let array2 = array {
  for element in array2 {
    ...
  }
}

This summary suggests that the force-unwrap is part of the behavior of for?, which might mislead someone reading this bit in isolation.

[jckarter]

Once an implementation is ready, we can queue the proposal for review.

[AnthonyLatsis]

Once an implementation is ready, we can queue the proposal for review.

Is it necessary for the implementation to be ready for merging (reviewed and approved)? I've got a working draft over here.