<html><head><style>body{font-family:Helvetica,Arial;font-size:13px}</style></head><body style="word-wrap:break-word"><div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;color:rgba(0,0,0,1.0);margin:0px;line-height:auto">Sounds like it would work if you don’t get bothered by the overhead of using a wrapper, including the extra lines of code for it. Even for the small example provided with the JSON, it would be a lot of extra boilerplate code. Any works just fine as long as you know what to put in it and what it contains. Interesting question though, what is the difference between the two, except that there is a nice switch operator and some more flexibility. I suppose they are rightly afraid that someone wil make a function that returns Int | String.</div> <br> <div id="bloop_sign_1489448349174392064" class="bloop_sign"></div> <br><p class="airmail_on">On March 13, 2017 at 7:23:24 PM, David Sweeris (<a href="mailto:davesweeris@mac.com">davesweeris@mac.com</a>) wrote:</p> <blockquote type="cite" class="clean_bq"><span><div style="word-wrap:break-word" class=""><div></div><div>
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<blockquote type="cite" class="">
<div class="">On Mar 12, 2017, at 7:52 PM, Elijah Johnson 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=""><span style="font-family:Helvetica,Arial;font-size:13px;font-style:normal;font-variant-caps:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;float:none;display:inline!important" class="">I don’t know if this feature has yet existed in any
languague, but its pretty simple.</span>
<div style="font-family:Helvetica,Arial;font-size:13px;font-style:normal;font-variant-caps:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px" class=""><br class=""></div>
<div style="font-family:Helvetica,Arial;font-size:13px;font-style:normal;font-variant-caps:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px" class="">Let say you are preparing data for a JSON encoder. Right
now, you would add to an Dictionary or Array like this one:</div>
<div style="font-family:Helvetica,Arial;font-size:13px;font-style:normal;font-variant-caps:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px" class=""><br class=""></div>
<div style="font-family:Helvetica,Arial;font-size:13px;font-style:normal;font-variant-caps:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px" class="">let data = [String:Any]();</div>
<div style="font-family:Helvetica,Arial;font-size:13px;font-style:normal;font-variant-caps:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px" class=""><br class=""></div>
<div style="font-family:Helvetica,Arial;font-size:13px;font-style:normal;font-variant-caps:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px" class="">but what one is really saying is that “Any” is from a
number of distinct types:</div>
<div style="font-family:Helvetica,Arial;font-size:13px;font-style:normal;font-variant-caps:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px" class=""><br class=""></div>
<div style="font-family:Helvetica,Arial;font-size:13px;font-style:normal;font-variant-caps:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px" class="">group typedef JSONValueType : String, Double, Int,
[String:JSONValueType], [JSONValueType], Bool</div>
<div style="font-family:Helvetica,Arial;font-size:13px;font-style:normal;font-variant-caps:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px" class=""><br class=""></div>
<div style="font-family:Helvetica,Arial;font-size:13px;font-style:normal;font-variant-caps:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px" class="">So from the compiler’s point of view, this group typedef
would be just like the “Any” type, only it would refuse to compile
unless the proper type was passed. So the result would be, as an
example, that there could be created an (almost) fail-safe JSON
encoder:</div>
<div style="font-family:Helvetica,Arial;font-size:13px;font-style:normal;font-variant-caps:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px" class=""><br class=""></div>
<div style="font-family:Helvetica,Arial;font-size:13px;font-style:normal;font-variant-caps:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px" class="">let data = [String:JSONValueType]();</div>
<div style="font-family:Helvetica,Arial;font-size:13px;font-style:normal;font-variant-caps:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px" class="">data[“key] = “value”;</div>
<div style="font-family:Helvetica,Arial;font-size:13px;font-style:normal;font-variant-caps:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px" class=""><br class=""></div>
<div style="font-family:Helvetica,Arial;font-size:13px;font-style:normal;font-variant-caps:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px" class="">I’m sure this has plenty of uses outside of JSON encoding
and would be pretty simple to do. One problem that it would solve
it the fact that in Swift, everything is included by Any, including
optionals, ex:</div>
<div style="font-family:Helvetica,Arial;font-size:13px;font-style:normal;font-variant-caps:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px" class=""><br class=""></div>
<div style="font-family:Helvetica,Arial;font-size:13px;font-style:normal;font-variant-caps:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px" class="">
<div style="margin:0px;font-size:11px;line-height:normal;font-family:Menlo" class=""><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)" class="">let</span><span style="font-variant-ligatures:no-common-ligatures" class=""><span class="Apple-converted-space"> </span>b :<span class="Apple-converted-space"> </span></span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)" class="">String</span><span style="font-variant-ligatures:no-common-ligatures" class="">?
=<span class="Apple-converted-space"> </span></span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)" class="">nil</span><span style="font-variant-ligatures:no-common-ligatures" class="">;</span></div>
<div style="margin:0px;font-size:11px;line-height:normal;font-family:Menlo" class=""><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)" class="">let</span><span style="font-variant-ligatures:no-common-ligatures" class=""><span class="Apple-converted-space"> </span>a :<span class="Apple-converted-space"> </span></span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)" class="">Any</span><span style="font-variant-ligatures:no-common-ligatures" class=""><span class="Apple-converted-space"> </span>= b; // result
is warning: “Expression implicitly coerced from String? to
Any"</span></div>
</div>
<div style="font-family:Helvetica,Arial;font-size:13px;font-style:normal;font-variant-caps:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px" class=""><br class=""></div>
<div style="font-family:Helvetica,Arial;font-size:13px;font-style:normal;font-variant-caps:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px" class="">and so there is no way to include value types and objects
without also including optionals, though this “Any” (like Object
and void* in Java/C) syntax makes for poorly documented code when
the type isn’t really “Any”, but a collection of known types.</div>
<div style="font-family:Helvetica,Arial;font-size:13px;font-style:normal;font-variant-caps:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px" class=""><br class=""></div>
<div style="font-family:Helvetica,Arial;font-size:13px;font-style:normal;font-variant-caps:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px" class="">There already exist protocols, but they are not useful for
types that one has not defined (like the basic system types), or
for mixing particular values, structs, and classes.</div>
</div>
</blockquote>
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<div>What are your thoughts on enums for this use-case?</div>
<div><br class=""></div>
<div>- Dave Sweeris</div>
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