proper tail calls

Neil Mix nmix at
Tue Jan 22 11:58:58 PST 2008

>> Its probably important to go back to Brendan's point about this  
>> being a
>> feature and not an optimization.  Even in Java the stack traces  
>> you get
>> are very distantly related to the actual code running when all the
>> inlining, escape analysis, and traditional optimizations are applied.
>> They jump through a lot of hoops to give you that valuable stack  
>> trace
>> in spite of all those optimizations and ES4 implementation will  
>> have to
>> do the same.
> This is a good point, but the standard may have little to do with  
> it (we have no standard backtrace methods or properties on Error  
> objects proposed at this point). The ControlInspector could be used  
> by programmers, but it is not mandated as part of the spec to help  
> hide PTC or other transformations. This leaves implementations to  
> compete on quality of debugging and tracing, which is likely to be  
> a growth area.

I also admit this is a good point.  If it's likely that  
implementations will go to the trouble of providing useful stack  
traces, than my arguments against implicit PTC are moot.  So the  
question (which I rely on you to judge for me since I have no skin in  
the implementation game) is, how big is that "if"?

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