[R] formals or args question

[BJ]

Hello again, thank you again for all of your help. I am trying to get 
the arguments for a function, in a way that I can handle them. If I do 
args(fun), it doesnt really do what I want. If I use formals(fun) i get 
output like:

$a


$r


$s


Now, lthis is supposedly a list, but if i say formals(a)[[1]], I get 
nothing. I am just trying to get a vector with teh arguments  of a 
function so I can loop over them.

ex; a<-function(p,r){p+r}

want: vector of c("p", "r")

The documentation for args and formals is quite confusing. Thanks again! 
~Erithid