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Merged
arthurfiorette merged 1 commit into from
Feb 23, 2025
Merged

Update spec.emu and add me to the author list #70

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1 change: 1 addition & 0 deletions README.md
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Expand Up @@ -483,6 +483,7 @@ This proposal is in its early stages, and we welcome your input to help refine i
## Authors

- [Arthur Fiorette](https://github.com/arthurfiorette) <sub>([X](https://x.com/arthurfiorette))</sub>
- [Arlen Beiler](https://github.com/Arlen22)

<br />

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212 changes: 124 additions & 88 deletions spec.emu
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Expand Up @@ -4,98 +4,134 @@
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/highlight.js/8.4/styles/github.min.css">
<script src="./spec.js"></script>
<pre class="metadata">
title: ECMAScript Safe Assignment Operator
title: ECMAScript Try Operator
stage: -1
contributors: Arthur Fiorette
contributors: Arthur Fiorette, Arlen Beiler
</pre>

<emu-biblio href="node_modules/@tc39/ecma262-biblio/biblio.json"></emu-biblio>

<emu-intro id="intro">
<h1>Introduction</h1>
<p>This proposal introduces syntax and semantics for safe assignments</p>
</emu-intro>
<emu-clause id="sec-assignment-operators">
<h1>Assignment Operators</h1>
<h2>Syntax</h2>
<emu-grammar type="definition">
AssignmentExpression[In, Yield, Await] :
TryExpression[?In, ?Yield, ?Await]
TryExpression[In, Yield, Await] :
`try` [no LineTerminator here] [lookahead != `{`] AssignmentExpression[?In, ?Yield, ?Await]
</emu-grammar>

<emu-clause id="sec-ecmascript-data-types-and-values" aoid="Type">
<h1>ECMAScript Data Types and Values</h1>
<emu-clause id="sec-ecmascript-language-types">
<h1>ECMAScript Language Types</h1>
<emu-clause id="sec-ecmascript-language-types-symbol-type">
<h1>The Symbol Type</h1>
<emu-clause id="sec-well-known-symbols">
<h1>Well-Known Symbols</h1>
<emu-table id="table-1" caption="Well-known Symbols">
<table>
<tbody>
<tr>
<th>
Specification Name
</th>
<th>
[[Description]]
</th>
<th>
Value and Purpose
</th>
</tr>
<tr>
<td>
<ins>@@result</ins>
</td>
<td>
<ins>`"Symbol.result"`</ins>
</td>
<td>
<ins>A method that wraps function call result into a tuple array. Called by the semantics of `?=` operator and `ResultableStack` objects.</ins>
</td>
</tr>
</tbody>
</table>
</emu-table>
</emu-clause>
</emu-clause>
<emu-clause id="sec-object-type">
<h1>The Object Type</h1>
<emu-clause id="sec-well-known-intrinsic-objects">
<h1>Well-Known Intrinsic Objects</h1>
<emu-table id="table-well-known-intrinsic-objects" caption="Well-Known Intrinsic Objects" oldids="table-7">
<table>
<tr>
<th>
Intrinsic Name
</th>
<th>
Global Name
</th>
<th>
ECMAScript Language Association
</th>
</tr>
<tr>
<td>
%Function%
</td>
<td>
`Function`
</td>
<td>
The Function constructor (<emu-xref href="#sec-function-constructor"></emu-xref>)
</td>
</tr>
<tr>
<td>
%Promise%
</td>
<td>
`Promise`
</td>
<td>
The Promise object (<emu-xref href="#sec-promise-objects"></emu-xref>)
</td>
</tr>
</table>
</emu-table>
</emu-clause>
</emu-clause>
<emu-clause id="sec-comma-operator-runtime-semantics-evaluation" type="sdo">
<h1>Runtime Semantics: Evaluation</h1>
<emu-grammar>TryExpression : `try` AssignmentExpression</emu-grammar>
<emu-alg>
1. Let _A_ be Completion(Evaluation of |Expression|).
1. If _A_ is an abrupt completion, return ? TryExpressionResult(_A_).
1. Let _B_ be Completion(GetValue(_A_)).
1. Return ? TryExpressionResult(_B_).
</emu-alg>
<emu-note>
<p>GetValue must be called even though its value is not used because it may have observable side-effects.</p>
</emu-note>
</emu-clause>
</emu-clause>

<emu-clause id="sec-try-expression-result" type="abstract operation">
<h1>
TryExpressionResult (
_result_: a Completion Record,
): either a normal completion containing a TryResult or an abrupt completion
</h1>
<dl class="header">
</dl>
<emu-alg>
1. If _result_ is a normal completion, return TryResult.ok(_result_.[[VALUE]]).
1. If _result_ is a throw completion, return TryResult.error(_result_.[[VALUE]]).
1. Return ? _result_.
</emu-alg>
</emu-clause>
<emu-clause id="sec-try-expression-result-ok" type="abstract operation">
<h1>
TryResult.ok (
_value_: an ECMAScript language value,
): a TryResult
</h1>
<dl class="header">
<dt>description</dt>
<dd>It is the abstract equivelant of calling `TryResult.ok(value)`</dd>
</dl>
</emu-clause>
<emu-clause id="sec-try-expression-result-error" type="abstract operation">
<h1>
TryResult.error (
_value_: an ECMAScript language value,
): a TryResult
</h1>
<dl class="header">
<dt>description</dt>
<dd>It is the abstract equivelant of calling `TryResult.error(value)`</dd>
</dl>
</emu-clause>
</emu-clause>

<emu-clause id="sec-well-known-intrinsic-objects">
<h1>Well-Known Intrinsic Objects</h1>
<emu-table id="table-well-known-intrinsic-objects" caption="Well-Known Intrinsic Objects" oldids="table-7">
<table>
<thead>
<tr>
<th>
Intrinsic Name
</th>
<th>
Global Name
</th>
<th>
ECMAScript Language Association
</th>
</tr>
</thead>
<tr>
<td>
%TryResult%
</td>
<td>
`TryResult`
</td>
<td>
The `TryResult` constructor (<emu-xref href="#sec-try-result-constructor"></emu-xref>)
</td>
</tr>
</table>
</emu-table>
</emu-clause>

<emu-clause id="sec-try-result-constructor">
<h1>The TryResult Constructor</h1>
<p>The TryResult constructor:</p>
<ul>
<li>is <dfn variants="TryResult">%TryResult%</dfn>.</li>
<li>is the initial value of the *"TryResult"* property of the global object.</li>
<li>is the functional equivelant of the following code:
<pre><code class="javascript">
class TryResult {
constructor(ok, error, value) {
this.ok = ok
this.error = error
this.value = value
}
*[Symbol.iterator]() {
yield this.ok
yield this.error
yield this.value
}
static ok(value) {
return new TryResult(true, undefined, value)
}
static error(error) {
return new TryResult(false, error, undefined)
}
}
</code></pre>
</li>
</ul>
</emu-clause>