On Jul 19, 2011, at 11:56 AM, Luke Hoban wrote:

>>> Object.extend(src, dest)
> 
>> This is certainly closest to paving the cowpath. Either via a built-in 
>> module exporting 'extend', or as you suggest, directly on Object. The 
>> Object.extend route is a bit harder to analyze, but not fatally so for any 
>> capable static analysis framework.
>> Either way (built-in module or Object.extend), old script (Hi Luke! ;-) 
>> could use it too.
> 
> Agreed - this was my initial reaction to <| as well, and I still see a number 
> of reasons to prefer a library solution over a syntax solution for both 
> 'Obect.extend' and 'Object.make'.
> 
> The arguments for <| as an operator seemed to boil down to:
> 1) It's more 'declarative'
> 2) It can be optimized by engines

One issue is that <| conceptually modifies the [[Prototype]] of its RHS.  As an 
operator (whether special character or keyword based) we can restrict the RHS 
to be a literal and define the behavior such that no actual mutation of 
[[Prototype]] is necessary.

However, at the value level we have no way to distinguish an object that was 
created via a literal and which has no references other than the current 
argument value.  So, when we specify Object.make we have to accept an arbitrary 
object as the second argument  and specify either [[Prototype]] mutation or 
some sort of shallow copy, either of which can be problematic. 

Allen
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