Functions like insistently(), safely(), slowly(), and quietly() help resolve challenging issues in programming. For example, safely() modifies a function to return both an error and a result. These functions work by returning an enhanced version of the original function. They are often called adverb functions and are typically named with an informative prefix such as safe_ or insist_. For instance, an insistent variant of scrape_data() created with insistently() might be called insist_scrape_data().

Exporting functions created with purrr adverbs in your package requires some precautions. Because the functions created by adverbs contain internal purrr code, creating them once and for all when the package is built might cause problems when purrr is updated. Instead, the function must be created by the purrr adverb each time the package is loaded in memory via the .onLoad() hook of the package. This prevents the generated functions to contain outdated internal purrr code (which could even refer to functions that no longer exist in the purrr namespace).

An example if provided below for insist, but it would be very similar for functions generated by other adverbs.

#' My function
insist_my_function <- function(...) "dummy"

my_function <- function(...) {
  # Implementation

.onLoad <- function(lib, pkg) {
  insist_my_function <<- purrr::insistently(my_function)