undefined being treated as a missing optional argument

Allen Wirfs-Brock allen at wirfs-brock.com
Fri Apr 13 13:16:20 PDT 2012

On Apr 13, 2012, at 12:16 PM, Brendan Eich wrote:

> ...

> No one wants to add yet another bottom type and singleton value.

Permitting "holes" in argument lists, eg Intl.Collator( , {usage:"search"})
doesn't require either at the user language level or the specification level. Whether a sentinel value would be needed to represent holes in argument lists at the implementation level is entirely an implement issue just like it is for sparse arrays. 

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