Go back and read the material on "Aborting a Search Through a List" in [[Week4]] for an example of doing this.
+In very general terms, the strategy is to work with functions like this:
+
+ let g' k (i : int) =
+ ... do stuff ...
+ ... if you want to abort early, supply an argument to k ...
+ ... do more stuff ...
+ ... normal result
+ in let gcon = fun result -> 1 + 2 * (1 - result)
+ in gcon (g' gcon (3 + 4))
+
+It's a convention to use variables like `k` for continuation arguments. If the function `g'` never supplies an argument to its contination argument `k`, but instead just finishes evaluating to a normal result, that normal result will be delivered to `g'`'s continuation `gcon`, just as happens when we don't pass around any explicit continuation variables.
+
+The above snippet of OCaml code doesn't really capture what happens when we pass explicit continuation variables. For suppose that inside `g'`, we do supply an argument to `k`. That would go into the `result` parameter in `gcon`. But then what happens once we've finished evaluating the application of `gcon` to that `result`? In the OCaml snippet above, the final value would then bubble up through the context in the body of `g'` where `k` was applied, and eventually out to the final line of the snippet, where it once again supplied an argument to `gcon`. That's not what happens with a real continuation. A real continuation works more like this:
+
+ let g' k (i : int) =
+ ... do stuff ...
+ ... if you want to abort early, supply an argument to k ...
+ ... do more stuff ...
+ ... normal result
+ in let gcon = fun result ->
+ let final_value = 1 + 2 * (1 - result)
+ in end_program_with final_value
+ in gcon (g' gcon (3 + 4))
+
+So once we've finished evaluating the application of `gcon` to a `result`, the program is finished. (This is how undelimited continuations behave. We'll discuss delimited continuations later.)
+
+So now, guess what would be the result of doing the following:
+
+ let g' k (i : int) =
+ 1 + k i
+ in let gcon = fun result ->
+ let final_value = (1, result)
+ in end_program_with final_value
+ in gcon (g' gcon (3 + 4))
+
+<!-- (1, 7) ... explain why not (1, 8) -->
+