Exercise

How does safely() work?
The source code looks like this:

safely
#> function (.f, otherwise = NULL, quiet = TRUE) 
#> {
#>     .f <- as_mapper(.f)
#>     force(otherwise)
#>     check_bool(quiet)
#>     function(...) capture_error(.f(...), otherwise, quiet)
#> }
#> <bytecode: 0x557c321c26b0>
#> <environment: namespace:purrr>

The real work is done in capture_error which is defined in the package namespace. We can access it with the ::: operator. (Could also grab it from the function’s environment.)

purrr:::capture_error
#> function (code, otherwise = NULL, quiet = TRUE) 
#> {
#>     tryCatch(list(result = code, error = NULL), error = function(e) {
#>         if (!quiet) 
#>             message("Error: ", conditionMessage(e))
#>         list(result = otherwise, error = e)
#>     })
#> }
#> <bytecode: 0x557c321d6510>
#> <environment: namespace:purrr>