<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div>Love it :)!<br><br>Sent from my iPhone</div><div><br>On 2 Oct 2016, at 09:37, Adrian Zubarev via swift-evolution <<a href="mailto:swift-evolution@swift.org">swift-evolution@swift.org</a>> wrote:<br><br></div><blockquote type="cite"><div><style>
body {
font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
padding:1em;
margin:auto;
background:#fefefe;
}
h1, h2, h3, h4, h5, h6 {
font-weight: bold;
}
h1 {
color: #000000;
font-size: 28pt;
}
h2 {
border-bottom: 1px solid #CCCCCC;
color: #000000;
font-size: 24px;
}
h3 {
font-size: 18px;
}
h4 {
font-size: 16px;
}
h5 {
font-size: 14px;
}
h6 {
color: #777777;
background-color: inherit;
font-size: 14px;
}
hr {
height: 0.2em;
border: 0;
color: #CCCCCC;
background-color: #CCCCCC;
display: inherit;
}
p, blockquote, ul, ol, dl, li, table, pre {
margin: 15px 0;
}
a, a:visited {
color: #4183C4;
background-color: inherit;
text-decoration: none;
}
#message {
border-radius: 6px;
border: 1px solid #ccc;
display:block;
width:100%;
height:60px;
margin:6px 0px;
}
button, #ws {
font-size: 12 pt;
padding: 4px 6px;
border-radius: 5px;
border: 1px solid #bbb;
background-color: #eee;
}
code, pre, #ws, #message {
font-family: Monaco;
font-size: 10pt;
border-radius: 3px;
background-color: #F8F8F8;
color: inherit;
}
code {
border: 1px solid #EAEAEA;
margin: 0 2px;
padding: 0 5px;
}
pre {
border: 1px solid #CCCCCC;
overflow: auto;
padding: 4px 8px;
}
pre > code {
border: 0;
margin: 0;
padding: 0;
}
#ws { background-color: #f8f8f8; }
.bloop_markdown table {
border-collapse: collapse;
font-family: Helvetica, arial, freesans, clean, sans-serif;
color: rgb(51, 51, 51);
font-size: 15px; line-height: 25px;
padding: 0; }
.bloop_markdown table tr {
border-top: 1px solid #cccccc;
background-color: white;
margin: 0;
padding: 0; }
.bloop_markdown table tr:nth-child(2n) {
background-color: #f8f8f8; }
.bloop_markdown table tr th {
font-weight: bold;
border: 1px solid #cccccc;
margin: 0;
padding: 6px 13px; }
.bloop_markdown table tr td {
border: 1px solid #cccccc;
margin: 0;
padding: 6px 13px; }
.bloop_markdown table tr th :first-child, table tr td :first-child {
margin-top: 0; }
.bloop_markdown table tr th :last-child, table tr td :last-child {
margin-bottom: 0; }
.bloop_markdown blockquote{
border-left: 4px solid #dddddd;
padding: 0 15px;
color: #777777; }
blockquote > :first-child {
margin-top: 0; }
blockquote > :last-child {
margin-bottom: 0; }
code, pre, #ws, #message {
word-break: normal;
word-wrap: normal;
}
hr {
display: inherit;
}
.bloop_markdown :first-child {
-webkit-margin-before: 0;
}
code, pre, #ws, #message {
font-family: Menlo, Consolas, Liberation Mono, Courier, monospace;
}
.send { color:#77bb77; }
.server { color:#7799bb; }
.error { color:#AA0000; }</style><div class="bloop_markdown"><p>That’s right. I was about to say something similar about the <code>Of</code>.</p>
<p>Actually <code>Type<T></code> would be the correct name for the static/concrete metatype.</p>
<ol>
<li>We already have this notation but not in a generic way <code>T.Type</code></li>
<li>If we add <code>of</code> only in our mind to <code>Type<T></code>, we’ll get “Type of a type T” which is shortly referred as a “metatype of T”. (<code>Array<Element></code> - Array of Element type)</li>
</ol>
<p>Since <code>Subtype<T></code> in reality is some *existential metatype* and the whole talk about existential types now tend to have the <code>Any</code> prefix, lets follow that trend here too.</p>
<ul>
<li><code>Type<T></code> - (static/concrete/exact) metatype.</li>
<li><code>AnyType<T></code> - existential metatype.</li>
</ul>
<p>It might be even easier to memorise this name than <code>Subtype</code>.</p>
<p>The example from the proposal rewritten:</p>
<pre><code class="swift">// Types:
protocol Foo {}
protocol Boo : Foo {}
class A : Foo {}
class B : A, Boo {}
struct S : Foo {}
// Metatypes:
let a1: Type<A> = A.self //=> Okay
let p1: Type<Foo> = Foo.self //=> Okay
let p2: Type<Boo> = C.self //=> Error -- `C` is not the same as `Foo`
let any_1: AnyType<Any> = A.self //=> Okay
let any_2: AnyType<Any> = Foo.self //=> Okay
let a_1: AnyType<A> = A.self //=> Okay
let p_1: AnyType<Foo> = A.self //=> Okay
let p_2: AnyType<Foo> = Foo.self //=> Error -- `Type<Foo>` is not a subtype of `AnyType<Foo>`
// Generic functions:
func dynamic<T>(type: AnyType<Any>, `is` _: Type<T>) -> Bool {
return type is AnyType<T>
}
func dynamic<T>(type: AnyType<Any>, `as` _: Type<T>) -> AnyType<T>? {
return type as? AnyType<T>
}
let s1: Type<S> = S.self
dynamic(type: s1, is: Foo.self) //=> true
dynamic(type: s1, as: Foo.self) //=> an `Optional<AnyType<Foo>>`
</code></pre>
<p>The <code>type(of:)</code> function could now stay, because now we’d only need to change the return type.</p>
<pre><code class="swift">func type<T>(of instance: T) -> AnyType<T>
</code></pre>
<p>Isn’t this a good compromise?</p>
<p></p></div><div class="bloop_original_html"><style>body{font-family:Helvetica,Arial;font-size:13px}</style><div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px; color: rgba(0,0,0,1.0); margin: 0px; line-height: auto;"><br></div> <br> <div id="bloop_sign_1475391764028646912" class="bloop_sign"><div style="font-family:helvetica,arial;font-size:13px">-- <br>Adrian Zubarev<br>Sent with Airmail</div></div> <br><p class="airmail_on">Am 2. Oktober 2016 um 09:01:45, Pyry Jahkola via swift-evolution (<a href="mailto:swift-evolution@swift.org">swift-evolution@swift.org</a>) schrieb:</p> <blockquote type="cite" class="clean_bq"><span><div><span style="color: rgb(0, 0, 0); font-family: 'helvetica Neue', helvetica; font-size: 14px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; background-color: rgb(255, 255, 255); display: inline !important; float: none;">OTOH, we don't have ArrayOf<Element> or DictionaryOfKeyAndValue<Key, Value>, while we still pronounce them that way. I don't think prepositions belong in the name of types but in exceptional cases, and this doesn't sound exceptional enough to me.</span></div></span></blockquote></div><div class="bloop_markdown"><p></p></div></div></blockquote><blockquote type="cite"><div><span>_______________________________________________</span><br><span>swift-evolution mailing list</span><br><span><a href="mailto:swift-evolution@swift.org">swift-evolution@swift.org</a></span><br><span><a href="https://lists.swift.org/mailman/listinfo/swift-evolution">https://lists.swift.org/mailman/listinfo/swift-evolution</a></span><br></div></blockquote></body></html>