Any blogs to help orient me re the referenceimplementation?contrasting with F#

Brendan Eich brendan at
Thu Mar 20 15:22:25 PDT 2008

On Mar 20, 2008, at 8:54 AM, Lars Hansen wrote:

> We have set aside placeholders for E4X syntax.  How useful this is I
> don't know; the experience with reserving future reserved words in ES3
> has been mostly negative (as a rule programmers don't read specs, and
> when they do, as a rule they ignore the "may be used in the future"
> clauses -- and I don't think they're wrong in doing so).

Generally I agree. Just for the record, the "future reserved words"  
go back to ES1 and were prefigured by Netscape's reserving all then- 
reserved Java identifiers. This was done with agreement and a great  
deal of spec-writing leadership by Microsoft, but the JScript engine  
nevertheless reserved only class, enum, extends, and super (if memory  

Over time, as Netscape went into decline, content grew to use  
identifiers such as 'char'. And of course we are contextually  
unreserving in ES4 (Firefox 2 / JS1.7 already does this), but it  
wouldn't help the 'char' case I recall, where the identifier was a  
parameter name.

This tale cautions about several things other than trying to reserve  
future syntax, among them the participants in the standard not  
following through early in their own products, before conflicts in  
the market could emerge.


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