Knuth claimed (I don’t have the book here, so please excuse the paraphrase and any misrepresentation) that one of the benefits of literate programming was that he could present the core program first, with simple “Handle errors from the file system” placeholders in appropriate places. So the main code remained relatively beautiful.

And then, when it was time to write the error-handling code, suddenly he found his perspective changed. The error-handling was no longer a distraction from the main problem to be solved; it was the first-class citizen it ought to be, a fresh, new, interesting problem in it’s own right, to be solved with rigour and enthusiasm. The sun shone, bunnies hopped, and the new age of peace and enlightenment dawned.

Now, Knuth was clearly slightly crazy. It should not be possible to get too excited about the many ways a help file may fail to open, and the problems presented by handling errors do not tend to be the most interesting ones a programmer may face. Nevertheless, I think there’s something of value there: since error-handling code always suffers in the shadow of the exciting stuff, people implementing grand new developer environments might want to provide ways to give it it’s own time and space.