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doc/go1.18: expand section on generics

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Also, move it up in the document.

Updates #47694

Change-Id: I927c4c845089a5c22e2c5b5f3de1831c04c6d990
Reviewed-on: https://go-review.googlesource.com/c/go/+/369102
Trust: Robert Griesemer <gri@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
This commit is contained in:
Robert Griesemer 2021-12-03 19:24:54 -08:00
parent cd5f2cf50f
commit 549cfefc72
1 changed files with 60 additions and 18 deletions
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78
doc/go1.18.html
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@ -29,6 +29,66 @@ Do not send CLs removing the interior tags from such phrases.
TODO: complete this section
</p>
<h3 id="generics">Generics</h3>
<p><!-- https://golang.org/issue/43651, https://golang.org/issue/45346 -->
Go 1.18 includes an implementation of generic features as described by the
<a href="https://go.googlesource.com/proposal/+/refs/heads/master/design/43651-type-parameters.md">Type
Parameters Proposal</a>.
This includes major - but fully backward-compatible - changes to the language.
The following is a list of the most visible changes. For a more comprehensive overview, see the
<a href="https://go.googlesource.com/proposal/+/refs/heads/master/design/43651-type-parameters.md">proposal</a>.
For details see the <a href="https://golang.org/ref/spec">language spec</a>.
</p>
<ul>
<li>
The new token <code>~</code> is added to the set of
<a href="https://golang.org/ref/spec#Operators_and_punctuation">operators and punctuation</a>.
</li>
<li>
The syntax for
<a href="https://golang.org/ref/spec#Function_declarations">Function</a> and
<a href="https://golang.org/ref/spec#Type_declarations">type declarations</a>
now accepts
<a href="https://golang.org/ref/spec#Type_parameters">type parameters</a>.
</li>
<li>
The syntax for
<a href="https://golang.org/ref/spec#Interface_types">Interface types</a>
now permits the embedding of arbitrary types (not just type names of interfaces)
as well as union and <code>~T</code> type elements. Such interfaces may only be used
as type constraints.
An interface now defines a set of types as well as a set of methods.
</li>
<li>
Parameterized functions and types can be instantiated by following them with a list of
type arguments in square brackets.
</li>
<li>
The new
<a href="https://golang.org/ref/spec#Predeclared_identifiers">predeclared identifier</a>
<code>any</code> is an alias for the empty interface. It may be used instead of
<code>interface{}</code>.
</li>
<li>
The new
<a href="https://golang.org/ref/spec#Predeclared_identifiers">predeclared identifier</a>
<code>comparable</code> is an interface the denotes the set of all types which can be
compared using <code>==</code> or <code>!=</code>. It may only be used as (or embedded in)
a type constraint.
</li>
</ul>
<p>
The current generics implementation has the following limitations:
<ul>
<li><!-- https://golang.org/issue/47631 -->
The Go compiler cannot currently handle type declarations inside generic functions
or methods. We hope to provide support for this feature in Go 1.19.
</li>
</ul>
</p>
<h3 id="bug_fixes">Bug fixes</h3>
<p>
@ -56,24 +116,6 @@ Do not send CLs removing the interior tags from such phrases.
programs is likely very small.
</p>
<h3 id="generics">Generics</h3>
<p>
Go 1.18 includes an implementation of generics as described
by <a href="https://go.googlesource.com/proposal/+/refs/heads/master/design/43651-type-parameters.md">the
generics proposal</a>.
</p>
<p>
The current generics implementation has the following limitations:
<ul>
<li><!-- issue 47631 -->
The Go compiler cannot currently handle type declarations inside generic functions
or methods. We hope to provide support for this feature in Go 1.19.
</li>
</ul>
</p>
<h3 id="fuzzing">Fuzzing</h3>
<p>