[R] Bug? using { as a function in lapply

[Liaw, Andy]

But (it seems like) "{" as a primitive function can take arbitrary number of
argument, and return the last argument.  So Gabor's usage seems right, yet
somehow within lapply() "{" doesn't like the way it's being called.

Also, be very careful:

> "{" <- function(x, y) y
> f <- function(a, b) { exp(a+b); a+b; a-b }
> f(1, 2)
Error in { : unused argument(s) ( ...)
> f <- function(a, b) { exp(a+b); a+b }
> f(1, 2)
[1] 3
> f <- function(a, b) { exp(a+b) }
> f(1, 2)
Error in { : Argument "y" is missing, with no default

Andy

> From: Witold 
> 
> Hi,
> 
>  > "{" <- function(x,y)y
>  > "{"(1,9)
> [1] 9
>  > lapply(1:2, "{", 9)
> [[1]]
> [1] 9
> 
> [[2]]
> [1] 9
> 
>  > R.version.string
> [1] "R version 2.0.0, 2004-09-20"
> 
> 
> /E
> 
> Gabor Grothendieck wrote:
> 
> >This seems like a bug to me.  Can someone verify this?  
> >
> >First we define a function f that returns its second argument and 
> >lapply it to 1:2 using 9 as the second argument and all seems well.
> >
> >Note that "{" as a function does the same thing as f, as illustrated 
> >with f(1,9) and "{"(1,9); however, when we attempt to use "{" in the 
> >very same way we used f in lapply, we get an error message about ... 
> >being used in an incorrect context, as shown.
> >
> >I am using R on windows with the version shown at the end.
> >
> >
> >R> f <- function(x,y)y
> >R> f(1,9)
> >[1] 9
> >R> lapply(1:2, f, 9)
> >[[1]]
> >[1] 9
> >
> >[[2]]
> >[1] 9
> > 
> >R> "{"(1,9)
> >[1] 9
> >R> lapply(1:2, "{", 9)
> >Error in lapply(1:2, "{", 9) : ... used in an incorrect context
> >
> >R> R.version.string
> >[1] "R version 1.9.1, 2004-08-03"
> >
> >______________________________________________
> >R-help at stat.math.ethz.ch mailing list
> >https://stat.ethz.ch/mailman/listinfo/r-help
> >PLEASE do read the posting guide! 
> http://www.R-project.org/posting-guide.html
> >
> >  
> >
> 
> 
> -- 
> 
> Dipl. bio-chem. Witold Eryk Wolski         
> MPI-Moleculare Genetic
> Ihnestrasse 63-73 14195 Berlin           _
> tel: 0049-30-83875219                   'v'
> http://www.molgen.mpg.de/~wolski       /   \
> mail: witek96 at users.sourceforge.net  ---W-W----
>       wolski at molgen.mpg.de
> 
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>