How to determine the decimal mark for the current system locale in R?

Question

I want to use readr::parse_number()for a character vector that has been guessed as a type "number" onreadr::guess_parser()

I can build a locale to do this work using readr::parse_number( readr::locale(decimal_mark = <a mark to be determined at run time>) )

So, the problem is that the system language is unknown until run time and can be anywhere in the world. Is there a way to determine the decimal mark from the system locale?