concreteness and understandability of the zipper provides a way of
understanding an equivalent treatment using continuations.
-Let's work with lists of `char`s for a change. To maximize readability, we'll
-indulge in an abbreviatory convention that "abSd" abbreviates the
-list `['a'; 'b'; 'S'; 'd']`.
+Let's work with lists of `char`s for a change. We'll sometimes write
+"abSd" as an abbreviation for
+`['a'; 'b'; 'S'; 'd']`.
We will set out to compute a deceptively simple-seeming **task: given a
string, replace each occurrence of 'S' in that string with a copy of
continuations with embedded `prompt`s (also called `reset`s).
The reason the task is well-suited to the list zipper is in part
-because the list monad has an intimate connection with continuations.
+because the List monad has an intimate connection with continuations.
We'll explore this next.