Wie leite ich (x => x) ab?

[1unitedpower]

Dieses Problem besteht nur für die zusammengefasste Syntax aus Anhang A der Spezifikation. Die normative Syntax hat eine Produktionsregel PostfixExpression : LeftHandSideExpression die es ermöglicht den Term in folgender Weise abzuleiten:

PrimaryExpression →
CoverParenthesizedExpressionAndArrowParameterList →
(Expression) →
(AssignmentExpression) →
(ArrowFunction) →
(ArrowParameters => ConciseBody) →
(ArrowParameters => AssignmentExpression)  →
(ArrowParameters => ConditionalExpression)  →
(ArrowParameters => LogicalORExpression)  →
(ArrowParameters => LogicalANDExpression) →
(ArrowParameters => BitwiseORExpression) →
(ArrowParameters => BitwiseXORExpression) →
(ArrowParameters => BitwiseANDExpression) →
(ArrowParameters => EqualityExpression) →
(ArrowParameters => RelationalExpression) →
(ArrowParameters => ShiftExpression) →
(ArrowParameters => AdditiveExpression) →
(ArrowParameters => MultiplicativeExpression) →
(ArrowParameters => UnaryExpression) →
(ArrowParameters => PostfixExpression) →
(ArrowParameters => LeftHandSideExpression) →
(ArrowParameters => NewExpression) →
(ArrowParameters => MemberExpression) →
(ArrowParameters => PrimaryExpression) →
(ArrowParameters => IdentifierReference) →
(ArrowParameters => Identifier) →
(ArrowParameters => IdentifierName) →
(ArrowParameters => IdentifierStart) →
(ArrowParameters => UnicodeIDStart) →
(ArrowParameters => x) →
(BindingIdentifier => x) →
(Identifier => x) →
(IdentifierName => x) →
(IdentifierStart => x) →
(UnicodeIDStart => x) →
(x => x)