[swift-evolution] Control Flow Expressions

[Sergey Shulepov]

Hello. 

It would be cool if control flow statements like "switch", "if" can be used as expressions, such as in languages like Scala, Rust and Kotlin,
so instead of writing:

var message: String
if x % 2 == 0 {
 message = "x is even"
} else {
 message = "x is odd"
}

you can write:

let message: String = if x % 2 == 0 { "x is even" } else { "x is odd" }

I'm not into any kind of compiler development, and don't know is it feasible to introduce such change at the moment, but at least, I would like to hear why not.
Thanks!