<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><br class=""><div><blockquote type="cite" class=""><div class="">On 05 Jun 2016, at 21:26, Антон Жилин via swift-evolution <<a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div dir="ltr" class=""><div class="">The following names were suggested: NoReturn, Bottom, None, Never.<br class=""></div><div class="">I would pick None, because it looks like opposite to Any and fits nicely in generic types.</div><div class=""></div></div></div></blockquote><div><br class=""></div><div>I would pick `<font face="Menlo" class="">Never</font>` because `<font face="Menlo" class="">None</font>` would overload the notion of a returnable nothingness with its antonym!</div><div><br class=""></div><div>OTOH, "never" is quite unlikely to be a type name in user code, likely pretty googleable, and explains itself quite well in examples like `<font face="Menlo" class="">Result<Value, Never></font>`.</div><br class=""><blockquote type="cite" class=""><div class=""><div dir="ltr" class=""><div class="">I would prefer the type to be simple, and be implemented as a case-less enum (not a bottom value, as in Haskell).<br class=""></div><div class=""><br class=""></div><div class="">None should be a usual enum, with no compiler magic except that functions returning None are equivalent to current @noreturn.</div></div></div></blockquote></div><br class=""><div class="">I think it would be more useful if the compiler allowed `<font face="Menlo" class="">Never</font>` in every type context (i.e. whatever type `<font face="Menlo" class="">T</font>` was expected, an expression of type `<font face="Menlo" class="">Never</font>` would be allowed), making expressions like the following compile:</div><div class=""><br class=""></div><div class=""><font face="Menlo" class=""> let unwrapped: Int = optional ?? fatalError("explanation why this must not happen")</font></div><div class=""><br class=""></div><div class="">— Pyry</div><div class=""><br class=""></div></body></html>