concreteness and understandability of the zipper provides a way of
understanding and equivalent treatment using continuations.
-Let's work with lists of chars for a change. To maximize readability, we'll
+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']`.
This is a task well-suited to using a zipper. We'll define a function
`tz` (for task with zippers), which accomplishes the task by mapping a
-char list zipper to a char list. We'll call the two parts of the
+`char list zipper` to a `char list`. We'll call the two parts of the
zipper `unzipped` and `zipped`; we start with a fully zipped list, and
-move elements to the zipped part by pulling the zipped down until the
+move elements to the zipped part by pulling the zipper down until the
entire list has been unzipped (and so the zipped half of the zipper is empty).
<pre>
concrete zipper using procedures.
Think of a list as a procedural recipe: `['a'; 'b'; 'S'; 'd']`
-is the result of the computation `a::(b::(S::(d::[])))` (or, in our old
-style, `makelist a (makelist b (makelist S (makelist c empty)))`).
+is the result of the computation `'a'::('b'::('S'::('d'::[])))` (or, in our old
+style, `make_list 'a' (make_list 'b' (make_list 'S' (make_list 'd' empty)))`).
The recipe for constructing the list goes like this:
<pre>
context, a continuation is a function of type `char list -> char
list`. For instance, the continuation corresponding to the portion of
the recipe below the horizontal line is the function `fun (tail:char
-list) -> a::(b::tail)`.
+list) -> 'a'::('b'::tail)`.
This means that we can now represent the unzipped part of our
-zipper--the part we've already unzipped--as a continuation: a function
+zipper---the part we've already unzipped---as a continuation: a function
describing how to finish building the list. We'll write a new
function, `tc` (for task with continuations), that will take an input
list (not a zipper!) and a continuation and return a processed list.