[SOLVED] How do I read an .tar.xz file?

How do I read an .tar.xz file?

I downloaded the Gwern Branwen dataset here: https://www.gwern.net/DNM-archives

I'm trying to read the dataset in R and I'm having a lot of trouble. I tried to open one of the files in the dataset called "1776.tar.xz" and I think I "unzipped" it with untar() but I'm not getting anything past that.

untar("C:/User/user/Downloads/dnmarchives/1776.tar.xz",
  files = NULL,
  list = FALSE, exdir = ".",
  compressed = "xz", extras = NULL, verbose = FALSE, restore_times = TRUE,
  tar = Sys.getenv("TAR"))

Edit: Thanks for all of the comments so far! The code is in base R. I have multiple datasets that I downloaded from Gwern's website. I'm just trying to open one to explore.

Solution

Thanks everyone! Not sure what was wrong with r for a bit but I reinstalled. I ended up unzipping manually and loading up the files.