rlang v0.1.2

Functions for Base Types and Core R and 'Tidyverse' Features

A toolbox for working with base types, core R features like the condition system, and core 'Tidyverse' features like tidy evaluation.



Build Status Coverage Status


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:


Or install the development version from github with:

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

Functions in rlang

Name Description
as_env Coerce to an environment
as_function Convert to function or closure
as_overscope Create a dynamic scope for tidy evaluation
as_pairlist Coerce to pairlist
as_quosure Coerce object to quosure
as_utf8_character Coerce to a character vector and attempt encoding conversion
abort Signal an error, warning, or message
are_na Test for missing values
arg_match Match an argument to a character vector
as_bytes Coerce to a raw vector
caller_env Get the environment of the caller frame
cnd_signal Signal a condition
env_names Names of symbols bound in an environment
env_parent Get parent environments
duplicate Duplicate an R object
empty_env Get the empty environment
env Create a new environment
bare-type-predicates Bare type predicates
call_inspect Inspect a call
env_depth Depth of an environment chain
env_get Get an object from an environment
exprs_auto_name Ensure that list of expressions are all named
f_rhs Get or set formula components
has_name Does an object have an element with this name?
invoke Invoke a function with a list of arguments
is_formula Is object a formula?
is_frame Is object a frame?
is_integerish Is a vector integer-like?
is_lang Is object a call?
dots_n How many arguments are currently forwarded in dots?
dots_values Evaluate dots with preliminary splicing
env_bury Overscope bindings by defining symbols deeper in a scope
env_clone Clone an environment
expr_interp Process unquote operators in a captured expression
eval_tidy Evaluate an expression tidily
eval_tidy_ Tidy evaluation in a custom environment
f_text Turn RHS of formula into a string or label
flatten Flatten or squash a list of lists into a simpler vector
lang_fn Extract function from a call
lang_head Return the head or tail of a call object
op-na-default Replace missing values
op-null-default Default value for NULL
prepend Prepend a vector
prim_name Name of a primitive function
set_chr_encoding Set encoding of a string or character vector
env_bind Bind symbols to objects in an environment
env_unbind Remove bindings from an environment
eval_bare Evaluate an expression in an environment
fn_env Return the closure environment of a function
fn_fmls Extract arguments from a function
is_copyable Is an object copyable?
is_empty Is object an empty vector or NULL?
dictionary Create a dictionary
dots_list Extract dots with splicing semantics
env_has Does an environment have or see bindings?
env_inherits Does environment inherit from another environment?
expr_label Turn an expression to a label
frame_position Find the position or distance of a frame on the evaluation stack
friendly_type Format a type for error messages
lang Create a call
lang_args Extract arguments from a call
missing_arg Generate or handle a missing argument
exiting Create an exiting or in place handler
expr Raw quotation of an expression
get_env Get or set the environment of an object
has_length How long is an object?
modify Modify a vector
new_cnd Create a condition object
new_formula Create a formula
dots_definitions Tidy quotation of multiple expressions and dots
restarting Create a restarting handler
is_callable Is an object callable?
is_condition Is object a condition?
is_symbol Is object a symbol?
is_true Is object identical to TRUE or FALSE?
is_env Is object an environment?
is_expr Is an object an expression?
is_named Is object named?
is_pairlist Is object a node or pairlist?
lang_modify Modify the arguments of a call
lang_name Extract function name of a call
new_function Create a function
ns_env Get the namespace of a package
quasiquotation Quasiquotation of an expression
is_function Is object a function?
is_installed Is a package installed in the library?
is_quosure Is an object a quosure or quosure-like?
rst_list Restarts utilities
rst_muffle Jump to a muffling restart
switch_type Dispatch on base types
set_expr Set and get an expression
stack Call stack information
stack_trim Trim top call layers from the evaluation stack
vector-coercion Coerce an object to a base type
quo-predicates Is a quosure quoting a symbolic, missing or NULL object?
sym Create a symbol or list of symbols
vector-len Create vectors matching a given length
with_env Evaluate an expression within a given environment
is_stack Is object a stack?
lang_standardise Standardise a call
missing Missing values
op-definition Definition operator
vector-construction Create vectors
set_names Set names of a vector
splice Splice a list within a vector
tidyeval-data Data pronoun for tidy evaluation
type-predicates Type predicates
with_handlers Establish handlers on the stack
with_restarts Establish a restart point on the stack
mut_utf8_locale Set the locale's codeset for testing
names2 Get names of a vector
pairlist Helpers for pairlist and language nodes
parse_expr Parse R code
quo_expr Splice a quosure and format it into string or label
quosure Create quosures
scalar-type-predicates Scalar type predicates
scoped_env Scoped environments
string Create a string
switch_lang Dispatch on call type
op-get-attr Infix attribute accessor
return_from Jump to or from a frame
rst_abort Jump to the abort restart
seq2 Increasing sequence of integers in an interval
set_attrs Add attributes to an object
type_of Base type of an object
vector-along Create vectors matching the length of a given vector
No Results!

Vignettes of rlang

No Results!


License GPL-3
LazyData true
VignetteBuilder knitr
RoxygenNote 6.0.1
Roxygen list(markdown = TRUE)
URL http://rlang.tidyverse.org, https://github.com/tidyverse/rlang
BugReports https://github.com/tidyverse/rlang/issues

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