Pitch: Multi-statement if/switch/do expressions

[Jumhyn (Frederick Kellison-Linn)]

@Jon_Shier

I recall the original version of 380 making return usage ambiguous by allowing returns through expressions, but I don't recall it being part of the original justification.

SE-0380 was accepted with an amendment banning all non-error control flow in if and switch expressions.

The discussion about return ambiguity was in reference to the immediately-applied closure workaround for the lack of if/switch expressions:

Finally, a closure can be used to simulate an if expression:

let bullet = {
    if isRoot && (count == 0 || !willExpand) { return "" }
    else if count == 0 { return "- " }
    else if maxDepth <= 0 { return "▹ " }
    else { return "▿ " }
}()

This also requires returns, plus some closure ceremony. But here the returns are more than ceremony – they require extra cognitive load to understand they are returning from a closure, not the outer function.