<div dir="ltr"><div class="gmail_extra"><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">Just added a section of motivating examples to the Either proposal. Ping me if you have any more that I missed ('cause I'm sure I did miss a lot).<br>
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<a href="https://github.com/typelift/swift-evolution/blob/either-or/proposals/0024-either.md#motivating-examples" rel="noreferrer" target="_blank">https://github.com/typelift/swift-evolution/blob/either-or/proposals/0024-either.md#motivating-examples</a><br>
<br></blockquote><div><br></div>Your motivating examples (including all the projects you linked except "Any many more") overwhelmingly use the Either (or similar type) to represent success/failure. I'm not sure there's a single example where the names Left and Right actually make sense in the problem domain. I'm not 100% sure about func alternate in Madness/Alternation.swift. It definitely uses Left/Right to mean Failure/Result, but I couldn't tell if it also uses them as something else. Which makes those names all the more maddening.<div><br></div><div>I checked my company's largest Scala project, which is over 300,000 lines. We use Scala's Try/Success/Failure in dozens of places. We use Either/Left/Right once, in a thrown-together report-generating script, which would probably have been written in awk or perl if it didn't need to read binary log files. (The ability of IntelliJ to reliably find all uses of a class or method is not to be underestimated. Hint hint, team Xcode.)</div><div><br></div><div>I think a Result/Success/Failure type is warranted, but I'm very skeptical about generic Either/Left/Right.</div><div><br></div></div></div></div>