> it with.
+ As Ken Shan points out, this is an instance of the algorithm
+ for converting name/year citations (like 'v. Montague 1970')
+ to numerals corresponding to their ('v. [24]'). Except that
+ bibliograpic numerals don't start with zero.
+
+ Give some thought to efficiency: there are straightforward
+ solutions that involve traversing the tree once (in order to,
+ say, construct a suitable mapping from leafs to ints), then
+ traversing it again to do the conversion. Can you find a
+ solution that traverses the tree exactly once, replacing each
+ leaf as soon as you see it?
+
+ Consider a variation in which you must replace each leaf with
+ is number of occurrences in the tree. Is there any way to do
+ that with a single traversal?
+
+ You can assume that the tree is leaf-labeled (no labels on the
+ internal nodes), and that the leafs are, say, chars.
+
Here is [a hint](/hints/assignment_10_hint).
(insert-co new before after (cdr lst) (lambda (new-lst lefts rights) ________))))))
-6. Go back to the "abSd" problem we presented in [[From List Zippers to Continuations]]. Consider the "tc" solution which uses explicitly passed continuations. Try to reimplement this using reset and shift instead of having an explicit `k` argument. This will likely be challenging but rewarding. The notes on [[CPS and Continuation Operators]], especially the examples at the end, should be helpful. We are of course also glad to help you out.
+6. Go back to the "abSd" problem we presented in [[From List Zippers to Continuations]]. Consider the "tc" solution which uses
+explicitly passed continuations. Try to reimplement this using reset
+and shift instead of having an explicit `k` argument. This will likely
+be challenging but rewarding. The notes on [[CPS and Continuation Operators]], especially the examples at the end, should be helpful. We
+are of course also glad to help you out.
+
+ Consider adding a special symbol `'#'` (pronounced 'prompt') to the
+ mini-language such that
+
+ `"ab#cdSef"` ~~> `"abcdcdef"`
+
+ That is, the rule for `'S'` is to copy the preceding string, but
+ only up to the closest enclosing `'#'` symbol.
7. Can you reimplement your solution to [[assignment9]] using reset and shift?