rlang v0.1.6


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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.



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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
arg_match Match an argument to a character vector
as_bytes Coerce to a raw vector
abort Signal an error, warning, or message
as_overscope Create a dynamic scope for tidy evaluation
as_pairlist Coerce to pairlist
as_function Convert to function or closure
dictionary Create a dictionary
bare-type-predicates Bare type predicates
dots_n How many arguments are currently forwarded in dots?
duplicate Duplicate an R object
caller_env Get the environment of the caller frame
empty_env Get the empty environment
env_has Does an environment have or see bindings?
env_inherits Does environment inherit from another environment?
eval_tidy Evaluate an expression tidily
eval_tidy_ Tidy evaluation in a custom environment
get_env Get or set the environment of an object
dots_values Evaluate dots with preliminary splicing
env_unbind Remove bindings from an environment
eval_bare Evaluate an expression in an environment
is_function Is object a function?
is_installed Is a package installed in the library?
is_true Is object identical to TRUE or FALSE?
lang Create a call
modify Modify a vector
has_length How long is an object?
is_copyable Is an object copyable?
is_empty Is object an empty vector or NULL?
lang_head Return the head or tail of a call object
env Create a new environment
env_bind Bind symbols to objects in an environment
expr_interp Process unquote operators in a captured expression
expr_label Turn an expression to a label
mut_utf8_locale Set the locale's codeset for testing
op-null-default Default value for NULL
pairlist Helpers for pairlist and language nodes
quo-predicates Is a quosure quoting a symbolic, missing or NULL object?
call_inspect Inspect a call
env_names Names of symbols bound in an environment
env_parent Get parent environments
exprs_auto_name Ensure that list of expressions are all named
exiting Create an exiting or in place handler
expr Raw quotation of an expression
has_name Does an object have an element with this name?
env_depth Depth of an environment chain
env_get Get an object from an environment
f_text Turn RHS of formula into a string or label
flatten Flatten or squash a list of lists into a simpler vector
invoke Invoke a function with a list of arguments
is_callable Is an object callable?
is_condition Is object a condition?
is_stack Is object a stack?
lang_modify Modify the arguments of a call
new_formula Create a formula
new_function Create a function
is_formula Is object a formula?
is_frame Is object a frame?
is_named Is object named?
is_pairlist Is object a node or pairlist?
f_rhs Get or set formula components
fn_env Return the closure environment of a function
fn_fmls Extract arguments from a function
is_quosure Is an object a quosure or quosure-like?
missing Missing values
missing_arg Generate or handle a missing argument
op-get-attr Infix attribute accessor
op-na-default Replace missing values
frame_position Find the position or distance of a frame on the evaluation stack
friendly_type Format a type for error messages
is_env Is object an environment?
is_symbol Is object a symbol?
names2 Get names of a vector
new_cnd Create a condition object
restarting Create a restarting handler
parse_expr Parse R code
prepend Prepend a vector
set_attrs Add attributes to an object
set_chr_encoding Set encoding of a string or character vector
splice Splice a list within a vector
quo_expr Splice a quosure and format it into string or label
rst_abort Jump to the abort restart
rst_list Restarts utilities
stack_trim Trim top call layers from the evaluation stack
is_expr Is an object an expression?
is_integerish Is a vector integer-like?
is_lang Is object a call?
lang_name Extract function name of a call
set_expr Set and get an expression
set_names Set names of a vector
sym Create a symbol or list of symbols
tidyeval-data Data pronoun for tidy evaluation
return_from Jump to or from a frame
scoped_env Scoped environments
seq2 Increasing sequence of integers in an interval
switch_lang Dispatch on call type
stack Call stack information
string Create a string
with_env Evaluate an expression within a given environment
with_handlers Establish handlers on the stack
switch_type Dispatch on base types
vector-coercion Coerce an object to a base type
lang_standardise Standardise a call
ns_env Get the namespace of a package
op-definition Definition operator
prim_name Name of a primitive function
quasiquotation Quasiquotation of an expression
rst_muffle Jump to a muffling restart
vector-along Create vectors matching the length of a given vector
scalar-type-predicates Scalar type predicates
type-predicates Type predicates
type_of Base type of an object
vector-construction Create vectors
vector-len Create vectors matching a given length
is_reference Is an object referencing another?
lang_args Extract arguments from a call
lang_fn Extract function from a call
quosure Create quosures
dots_definitions Tidy quotation of multiple expressions and dots
with_restarts Establish a restart point on the stack
as_quosure Coerce object to quosure
cnd_signal Signal a condition
as_env Coerce to an environment
as_utf8_character Coerce to a character vector and attempt encoding conversion
are_na Test for missing values
dots_list Extract dots with splicing semantics
env_bury Overscope bindings by defining symbols deeper in a scope
env_clone Clone an environment
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Vignettes of rlang

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License GPL-3
LazyData true
VignetteBuilder knitr
RoxygenNote 6.0.1
URL http://rlang.tidyverse.org, https://github.com/tidyverse/rlang
BugReports https://github.com/tidyverse/rlang/issues
NeedsCompilation yes
Packaged 2017-12-21 16:29:51 UTC; lionel
Repository CRAN
Date/Publication 2017-12-21 21:15:03 UTC

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