On Nov 26, 2013, at 11:36 AM, Brendan Eich wrote:

> Kevin Smith wrote:
>> Yes, I see that now.  Has anyone done compatibility-hazard analysis for this breaking change?
>> 
>>    ;
>>    let["a"].foo() // Fine in ES5 non-strict, fails in ES6?
> 
> That old chestnut! (Unquote "a" for better ambiguity.)
> 
> http://esdiscuss.org/topic/let-and-strict-mode
> 
> I honestly forget how we decided to go for let at start of statement followed by [ -- but I do recall we agreed not to have name-binding-sensitive parsing(!). I.e., we would not look for 'var let = ...' and treat 'let' in that (hoisted) scope as a non-keyword.

http://people.mozilla.org/~jorendorff/es6-draft.html#sec-expression-statement 

let [...

is not an ExpressionStatement.  I requires two token look-ahead for this one special case.

Allen

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On Nov 26, 2013, at 11:36 AM, Brendan Eich wrote:

> I honestly forget how we decided to go for let at start of statement followed by [ -- but I do recall we agreed not to have name-binding-sensitive parsing(!). I.e., we would not look for 'var let = ...' and treat 'let' in that (hoisted) scope as a non-keyword.

http://people.mozilla.org/~jorendorff/es6-draft.html#sec-expression-statement 

```js
let [...
```

is not an ExpressionStatement.  I requires two token look-ahead for this one special case.