On Oct 15, 2008, at 2:36 PM, Waldemar Horwat wrote:
There is no such thing as a "let expression".
Let expressions in JS1.7 (Firefox 2+), based on the ES4 proposal. ES3-
ish grammar:
LetExpression :
let ( VariableDeclarationList ) [lookahead ∉ {{}]
AssignmentExpression
produced from PrimaryExpression.
It's mandatory because the grammar and semicolon insertion rules say
so. Btw, to properly terminate a lambda expression you'd need *two*
semicolons. Here's why one would be insufficient:
f = lambda(x) x;
(a + b) && c;
would parse the body of the lambda as the expression "x;", the "(a +
b)" as an argument to the lambda, and the rest as applying to the
result of calling the lambda. What you'd want to write instead
would be:
f = lambda(x) x;;
Expression closures in JS1.8 (Firefox 3+) do not have this problem.
Using ES3's notation:
FunctionDeclaration :
function Identifier ( FormalParameterListopt ) FunctionBody
FunctionExpression :
function Identifieropt ( FormalParameterListopt ) FunctionBody
FormalParameterList :
Identifier
FormalParameterList , Identifier
FunctionBody :
{ SourceElements }
[lookahead ∉ {{}] AssignmentExpression
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