Question

In R, one does ?plot in order to get help for the plot.

Is there a way to get help in command line for the internal structures of the language, for example, about variable function arguments ‘…’, different type of array access [] or [[]], $, etc ?

> help("...")
No documentation for ‘...’ in specified packages and libraries:
you could try ‘??...’

Answer 1

For indexing functions, you can use :

help("[")

This works because [, for example, is in fact a function by itself, as you can see if you do :

x <- 1:5
do.call("[", list(x, 2))
[1] 2

Whereas ... is not a function, so help("...") won’t work.