Consistency in The Negative Result Values Through Expansion of null's Role

Brendan Eich brendan at mozilla.org
Mon Aug 20 22:39:57 PDT 2012


Brendan Eich wrote:
> I will take the charge of "contrived" but still maintain that -1 
> rather than undefined can be useful (as in used in a further index 
> computation), while undefined either needs a test to special-case (and 
> avoid hard-to-see implicit conversion), or else a conversion to NaN 
> that happens to work (a "good" implicit conversion? Not in your book, 
> I'm sure!). 

Also, the monotyped approach is easier to optimize, all else equal. See 
http://qfox.nl/weblog/265 for testimony about this (find "JIT mixed 
messages").

/be


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