These predicates check for a given type and whether the vector is "scalar", that is, of length 1.
In addition to the length check, is_string() and is_bool()
return FALSE if their input is missing. This is useful for
type-checking arguments, when your function expects a single string
or a single TRUE or FALSE.
is_scalar_list(x)is_scalar_atomic(x)
is_scalar_vector(x)
is_scalar_integer(x)
is_scalar_double(x)
is_scalar_complex(x)
is_scalar_character(x)
is_scalar_logical(x)
is_scalar_raw(x)
is_string(x, string = NULL)
is_scalar_bytes(x)
is_bool(x)
object to be tested.
A string to compare to x. If a character vector,
returns TRUE if at least one element is equal to x.
type-predicates, bare-type-predicates