Note: future hasn't been updated in a while. The 'backports' package provides similar functionality and is more up to date. Give it a look if you're interested.
The future
package is a convenience package meant to load the necessary other futureX.Y packages. These other packages essentially provide the best approximations to the functions introduced in specific versions of R so that users stuck with older versions of R can still have access to some of these nicer functions.
Currently there isn't a release on CRAN.
You can, however, download the zip ball or tar ball, decompress and run R CMD INSTALL
on it, or use the devtools package to install the development version:
## Make sure your current packages are up to date
update.packages()
## devtools is required
library(devtools)
install_github("future", "Dasonk")