Define a new type of for loop in R?

I am trying to work out how to define a custom for loop in R, or if that's even possible.

Examples

A couple of things that would be nice to have are

• something equivalent to ruby's each_with_index, as well as
• A for loop that completely ignores exceptions (without having to manually code exception handling into the loop).

Is it possible to define a new kind of for loop in R (and if so, how), or is this an inherent limitation of the language and hence not something that can be done?

Use cases

Here's a random example of how for_each_with_index could simplify finicky arithmetic

Suppose we want to scrape the 36th to the 55th article from a website and assign the output to a position in a list. This works well

library(rvest)
library(dplyr)
articles <- vector(mode = "list", length = 20)
for(i in 36:55) {
  paste0("Scraping article ", i) %>% print
  articles[[i - 35]] <- read_html(paste0("http://afr.herokuapp.com/articles/", i)) %>% 
             html_nodes("p") %>% html_text %>% paste0(collapse="/n")
           }

But we see some finicky arithmetic (36:55, i - 35 etc) that could theoretically be abstracted away through for_each_with_index enumerating over each element of the articles object, like so:

# NOT ACTUAL R CODE

library(rvest)
library(dplyr)
articles <- vector(mode = "list", length = 20)
for_each_with_index(articles, i) {
  paste0("Scraping article ", i) %>% print
  articles[[i]] <- read_html(paste0("http://afr.herokuapp.com/articles/", i + 35)) %>% 
             html_nodes("p") %>% html_text %>% paste0(collapse="/n")
           }

By using for_each_with_index, we avoided the fiddly arithmetic . This example is very simple, but when the complexity turns up some notches i.e when we have various conditionals, nested loops etc, things get much more complex and these seemingly small improvements in clarity become more profound