The rlang package provides tools to work with core language features of R and the tidyverse:

• The tidyeval framework, which is a well-founded system for non-standard evaluation built on quasiquotation (UQ()) and quosures (quo()). Read more in vignette("tidy-evaluation").

• Consistent tools for working with base types:

  • Vectors, including construction (lgl(), int(), ...) coercion (as_logical(), as_character(), ...), and predicates (is_logical(), is_character()).

  • Language objects, such as calls (lang()) and symbols (sym()).

  • Attributes, e.g. set_attrs(), set_names().

  • Functions, e.g. new_function(), as_function(), is_function().

  • Environments, e.g. env(), env_has(), env_get(), env_bind(), env_unbind().

• A comprehensive set of predicates to determine if an object satisfies various conditions, e.g. has_length(), is_list(), is_empty().

• The condition (message, warning, error) and restart system.

• Call and context stacks.

You can install the released version of rlang from CRAN with:

install.packages("rlang")

Or install the development version from github with:

# install.packages("devtools")
devtools::install_github("tidyverse/rlang", build_vignettes = TRUE)