[Rd] vapply definition question

[Radford Neal]

> so I guess you're looking at a modified version of the function... The 
> implementation detail is in the comment -- FUN(X[i], ...) is evaluated in the 
> frame of lapply.
> 
> Martin Morgan

You may find it interesting that in the latest version of pqR, lapply is made
faster in the case where no ... is used by then not actuallly passing ... to
FUN, which significatly reduces call overhead.  See the code at

  https://github.com/radfordneal/pqR/blob/Release-2014-11-16/src/main/apply.c