[R] Controlling visibility of top-level functions

[Paul A. Steckler]

I'm fairly new to R, and have checked the R FAQ and done an RSiteSearch for help
on this topic, to no avail.

I want to write some R code that has functions at the top-level that
are not visible when
the code is loaded. So in

  fun1 <- function(...)  { ... }

  fun2 <- function(...)  { ... fun1 ...}

I'd like fun2 to be callable, but have fun1 be invisible. That is, the
scope of fun1 is
limited to the file in which it's defined.

In Python, I believe that prepending an underscore to a variable name
limits its scope in this way.
Is there a similar mechanism in R?

-- Paul