Update spec.emu

Author: arthurfiorette

spec.emu

@@ -12,6 +12,9 @@ contributors: Arthur Fiorette, Arlen Beiler
 
 <emu-intro id="sec-intro">
   <h1>Introduction</h1>
+  <emu-note>
+    <p><strong>Important Notice:</strong> Until this proposal is accepted by ECMA, this spec.emu file might not reflect the latest updates to the proposal. Readers should base their understanding primarily on the current <a href="https://github.com/arthurfiorette/proposal-try-operator/blob/main/README.md">README.md</a> file, which serves as the authoritative source during the proposal stage. This specification is an imagination of what the final specification might look like and while it can be trusted as a reference, the README.md has higher importance at this stage of the project.</p>
+  </emu-note>
   <p>This proposal introduces a `try` operator and `Result` class to JavaScript for improved error handling ergonomics. The `try` operator evaluates an expression within an implicit try-catch block and returns a `Result` instance containing either the successful value or the caught error.</p>
 </emu-intro>
 
@@ -20,13 +23,25 @@ contributors: Arthur Fiorette, Arlen Beiler
 
   <emu-clause id="sec-result-constructor">
     <h1>The Result Constructor</h1>
-    <p>The Result constructor is not intended to be called as a constructor. It throws a *TypeError* exception if called with `new`.</p>
+    <p>The Result constructor is the %Result% intrinsic object. When called as a constructor, it creates and initializes a new Result object.</p>
 
     <emu-clause id="sec-result">
-      <h1>Result ( )</h1>
-      <p>When `Result` is called, the following steps are taken:</p>
+      <h1>Result ( _ok_, _error_, _value_ )</h1>
+      <p>When `Result` is called with arguments _ok_, _error_, and _value_, the following steps are taken:</p>
       <emu-alg>
-        1. Throw a *TypeError* exception.
+        1. If NewTarget is *undefined*, throw a *TypeError* exception.
+        1. Let _result_ be ? OrdinaryCreateFromConstructor(NewTarget, *"%Result.prototype%"*, « [[ResultState]], [[ResultValue]], [[ResultError]] »).
+        1. Let _booleanOk_ be ToBoolean(_ok_).
+        1. Perform ! CreateDataPropertyOrThrow(_result_, *"ok"*, _booleanOk_).
+        1. If _booleanOk_ is *true*, then
+          1. Set _result_.[[ResultState]] to ~success~.
+          1. Set _result_.[[ResultValue]] to _value_.
+          1. Perform ! CreateDataPropertyOrThrow(_result_, *"value"*, _value_).
+        1. Else,
+          1. Set _result_.[[ResultState]] to ~failure~.
+          1. Set _result_.[[ResultError]] to _error_.
+          1. Perform ! CreateDataPropertyOrThrow(_result_, *"error"*, _error_).
+        1. Return _result_.
       </emu-alg>
     </emu-clause>
   </emu-clause>
@@ -38,9 +53,7 @@ contributors: Arthur Fiorette, Arlen Beiler
       <h1>Result.ok ( _value_ )</h1>
       <p>When the `Result.ok` method is called with argument _value_, the following steps are taken:</p>
       <emu-alg>
-        1. Let _result_ be OrdinaryObjectCreate(%Result.prototype%, « [[ResultState]], [[ResultValue]] »).
-        1. Set _result_.[[ResultState]] to ~success~.
-        1. Set _result_.[[ResultValue]] to _value_.
+        1. Let _result_ be ? Construct(%Result%, « *true*, *undefined*, _value_ »).
         1. Return _result_.
       </emu-alg>
     </emu-clause>
@@ -49,24 +62,45 @@ contributors: Arthur Fiorette, Arlen Beiler
       <h1>Result.error ( _error_ )</h1>
       <p>When the `Result.error` method is called with argument _error_, the following steps are taken:</p>
       <emu-alg>
-        1. Let _result_ be OrdinaryObjectCreate(%Result.prototype%, « [[ResultState]], [[ResultError]] »).
-        1. Set _result_.[[ResultState]] to ~failure~.
-        1. Set _result_.[[ResultError]] to _error_.
+        1. Let _result_ be ? Construct(%Result%, « *false*, _error_, *undefined* »).
         1. Return _result_.
       </emu-alg>
     </emu-clause>
 
     <emu-clause id="sec-result.try">
-      <h1>Result.try ( _fn_, ..._args_ )</h1>
-      <p>When the `Result.try` method is called with argument _fn_ and optional arguments _args_, the following steps are taken:</p>
+      <h1>Result.try ( _arg_, ..._args_ )</h1>
+      <p>When the `Result.try` method is called with argument _arg_ and optional arguments _args_, the following steps are taken:</p>
       <emu-alg>
-        1. If IsCallable(_fn_) is *false*, throw a *TypeError* exception.
-        1. Let _result_ be Completion(Call(_fn_, *undefined*, _args_)).
-        1. If _result_ is an abrupt completion, then
-          1. Return ! Call(%Result.error%, %Result%, « _result_.[[Value]] »).
-        1. Else,
-          1. Return ! Call(%Result.ok%, %Result%, « _result_.[[Value]] »).
+        1. Let _completion_ be Completion(ResultTryImplementation(_arg_, _args_)).
+        1. If _completion_ is an abrupt completion, then
+          1. Return ! Call(%Result.error%, %Result%, « _completion_.[[Value]] »).
+        1. Return _completion_.[[Value]].
       </emu-alg>
+
+      <emu-clause id="sec-result-try-implementation" type="abstract operation">
+        <h1>ResultTryImplementation ( _arg_, _args_ )</h1>
+        <dl class="header">
+        </dl>
+        <emu-alg>
+          1. Let _result_ be *undefined*.
+          1. If IsCallable(_arg_) is *true*, then
+            1. Let _callResult_ be Completion(Call(_arg_, *undefined*, _args_)).
+            1. If _callResult_ is an abrupt completion, then
+              1. Return ! Call(%Result.error%, %Result%, « _callResult_.[[Value]] »).
+            1. Set _result_ to _callResult_.[[Value]].
+          1. Else,
+            1. Set _result_ to _arg_.
+          1. If _result_ is an Object and IsPromise(_result_) is *true*, then
+            1. Let _fulfillmentHandler_ be a new Abstract Closure with parameters (_value_) that captures nothing and performs the following steps when called:
+              1. Return ! Call(%Result.ok%, %Result%, « _value_ »).
+            1. Let _rejectionHandler_ be a new Abstract Closure with parameters (_reason_) that captures nothing and performs the following steps when called:
+              1. Return ! Call(%Result.error%, %Result%, « _reason_ »).
+            1. Let _onFulfilled_ be CreateBuiltinFunction(_fulfillmentHandler_, 1, *""*, « »).
+            1. Let _onRejected_ be CreateBuiltinFunction(_rejectionHandler_, 1, *""*, « »).
+            1. Return PerformPromiseThen(_result_, _onFulfilled_, _onRejected_).
+          1. Return ! Call(%Result.ok%, %Result%, « _result_ »).
+        </emu-alg>
+      </emu-clause>
     </emu-clause>
 
     <emu-clause id="sec-result.prototype">
@@ -85,39 +119,6 @@ contributors: Arthur Fiorette, Arlen Beiler
       <li>has a [[Prototype]] internal slot whose value is %Object.prototype%.</li>
     </ul>
 
-    <emu-clause id="sec-result.prototype.ok">
-      <h1>get Result.prototype.ok</h1>
-      <p>`Result.prototype.ok` is an accessor property whose set accessor function is *undefined*. Its get accessor function performs the following steps:</p>
-      <emu-alg>
-        1. Let _result_ be the *this* value.
-        1. Perform ? RequireInternalSlot(_result_, [[ResultState]]).
-        1. If _result_.[[ResultState]] is ~success~, return *true*.
-        1. Return *false*.
-      </emu-alg>
-    </emu-clause>
-
-    <emu-clause id="sec-result.prototype.value">
-      <h1>get Result.prototype.value</h1>
-      <p>`Result.prototype.value` is an accessor property whose set accessor function is *undefined*. Its get accessor function performs the following steps:</p>
-      <emu-alg>
-        1. Let _result_ be the *this* value.
-        1. Perform ? RequireInternalSlot(_result_, [[ResultState]]).
-        1. If _result_.[[ResultState]] is ~failure~, throw a *TypeError* exception.
-        1. Return _result_.[[ResultValue]].
-      </emu-alg>
-    </emu-clause>
-
-    <emu-clause id="sec-result.prototype.error">
-      <h1>get Result.prototype.error</h1>
-      <p>`Result.prototype.error` is an accessor property whose set accessor function is *undefined*. Its get accessor function performs the following steps:</p>
-      <emu-alg>
-        1. Let _result_ be the *this* value.
-        1. Perform ? RequireInternalSlot(_result_, [[ResultState]]).
-        1. If _result_.[[ResultState]] is ~success~, throw a *TypeError* exception.
-        1. Return _result_.[[ResultError]].
-      </emu-alg>
-    </emu-clause>
-
     <emu-clause id="sec-result.prototype-@@iterator">
       <h1>Result.prototype [ %Symbol.iterator% ] ( )</h1>
       <p>When the %Symbol.iterator% method is called, the following steps are taken:</p>
@@ -177,15 +178,22 @@ contributors: Arthur Fiorette, Arlen Beiler
           1. Let _index_ be _iterator_.[[ResultIteratorNextIndex]].
           1. If _index_ is 0, then
             1. Set _iterator_.[[ResultIteratorNextIndex]] to 1.
-            1. Return CreateIteratorResultObject(_result_.[[ResultState]] is ~success~, *false*).
+            1. Let _okValue_ be ? Get(_result_, *"ok"*).
+            1. Return CreateIteratorResultObject(_okValue_, *false*).
           1. Else if _index_ is 1, then
             1. Set _iterator_.[[ResultIteratorNextIndex]] to 2.
-            1. If _result_.[[ResultState]] is ~success~, return CreateIteratorResultObject(*undefined*, *false*).
-            1. Else, return CreateIteratorResultObject(_result_.[[ResultError]], *false*).
+            1. If ? HasProperty(_result_, *"error"*) is *true*, then
+              1. Let _errorValue_ be ? Get(_result_, *"error"*).
+              1. Return CreateIteratorResultObject(_errorValue_, *false*).
+            1. Else,
+              1. Return CreateIteratorResultObject(*undefined*, *false*).
           1. Else if _index_ is 2, then
             1. Set _iterator_.[[ResultIteratorNextIndex]] to 3.
-            1. If _result_.[[ResultState]] is ~success~, return CreateIteratorResultObject(_result_.[[ResultValue]], *false*).
-            1. Else, return CreateIteratorResultObject(*undefined*, *false*).
+            1. If ? HasProperty(_result_, *"value"*) is *true*, then
+              1. Let _valueValue_ be ? Get(_result_, *"value"*).
+              1. Return CreateIteratorResultObject(_valueValue_, *false*).
+            1. Else,
+              1. Return CreateIteratorResultObject(*undefined*, *false*).
           1. Else,
             1. Return CreateIteratorResultObject(*undefined*, *true*).
         </emu-alg>
@@ -218,13 +226,13 @@ contributors: Arthur Fiorette, Arlen Beiler
       <h1>Runtime Semantics: Evaluation</h1>
       <emu-grammar>UnaryExpression : `try` UnaryExpression</emu-grammar>
       <emu-alg>
-        1. Let _expr_ be the result of evaluating |UnaryExpression|.
-        1. If _expr_ is an abrupt completion, then
-          1. Return ! Call(%Result.error%, %Result%, « _expr_.[[Value]] »).
-        1. Let _value_ be ! GetValue(_expr_).
+        1. Let _exprRef_ be Completion(Evaluation of |UnaryExpression|).
+        1. If _exprRef_ is an abrupt completion, then
+          1. Return ! Call(%Result.error%, %Result%, « _exprRef_.[[Value]] »).
+        1. Let _value_ be Completion(GetValue(_exprRef_)).
         1. If _value_ is an abrupt completion, then
           1. Return ! Call(%Result.error%, %Result%, « _value_.[[Value]] »).
-        1. Return ! Call(%Result.ok%, %Result%, « _value_ »).
+        1. Return ! Call(%Result.ok%, %Result%, « _value_.[[Value]] »).
       </emu-alg>
     </emu-clause>
   </emu-clause>