check_type_scalar: Check argument type (scalar)

In rlang: Functions for Base Types and Core R and 'Tidyverse' Features

Check argument type (scalar)

Description

These functions check that an argument is of the expected scalar type and produce friendly error messages otherwise.

Usage

check_bool(
  x,
  ...,
  allow_na = FALSE,
  allow_null = FALSE,
  arg = caller_arg(x),
  call = caller_env()
)

check_string(
  x,
  ...,
  allow_empty = TRUE,
  allow_na = FALSE,
  allow_null = FALSE,
  arg = caller_arg(x),
  call = caller_env()
)

Arguments

x	The argument to check.
...	Additional arguments passed to abort().
allow_na	Whether NA values are allowed.
allow_null	Whether NULL is allowed.
arg	An argument name as a string. This argument will be mentioned in error messages as the input that is at the origin of a problem.
call	The execution environment of a currently running function, e.g. caller_env(). The function will be mentioned in error messages as the source of the error. See the call argument of abort() for more information.
allow_empty	Whether the empty string "" is allowed (check_string() only).

Value

NULL invisibly if the check passes, throws an error otherwise.

See Also

Other input checkers: check_data_frame(), check_type_number, stop_input_type()

Examples

check_bool(TRUE)
try(check_bool(1))

check_string("hello")
try(check_string(42))

rlang documentation built on April 6, 2026, 5:07 p.m.