## Announcements ##
+* [[Untyped lambda calculus evaluator|code/lambda_evaluator]] on this site
+
* This wiki will be undergoing lots of changes throughout the semester, and particularly in these first few days as we get it set up, migrate over some of the content from the previous time
we taught this course, and iron out various technical wrinkles. Please be patient. When you sit down to read the wiki, it's a good idea to always hit "Refresh" in your browser to make sure you're reading the latest additions and refinements of the website. (Sometimes these will be tweaks, other times very substantial. Updates will happen at miscellaneous hours, sometimes many times in a given day.)
- If you've eager to learn, though, you don't have to wait on us to be ready to serve you. You can go look at the [archived first version](http://lambda1.jimpryor.net) of this course. Just keep in mind that
+ If you're eager to learn, though, you don't have to wait on us to be ready to serve you. You can go look at the [archived first version](http://lambda1.jimpryor.net) of this course. Just keep in mind that
the text and links there haven't been updated. And/or you can get started on installing the software and ordering some of the books.
* As we mentioned in class, if you're following the course and would like to be emailed occasionally, send an email to <mailto:jim.pryor@nyu.edu>, saying "lambda" in the subject line. Most often, we will just post announcements to this website, rather than emailing you. But occasionally an email might be more appropriate.
> Topics:
[[Intro to the Lambda Calculus|topics/week2 lambda intro]];
[[Advanced notes|topics/week2 lambda advanced]];
-Encoding Booleans, Tuples, Lists, and Numbers (in progress);
-Homework (in progress)
+[[Encoding Booleans, Tuples, Lists, and Numbers|topics/week2 encodings]];
+[[Homework|exercises/assignment2]]
> Also, if you're reading the Hankin book, try reading Chapters 1-3. You will most likely need to come back again and read it multiple times; but this would be a good time to make the first attempt.
+> We posted [[answers to Week 1's homework|exercises/assignment1_answers]].
+
+(**Week 3**) Thursday 12 February 2015
+
+> Topics:
+[[Arithmetic with Church numbers|topics/week3_church_arithmetic]];
+[[More on Lists|topics/week3 lists]];
+[[What is computation?|topics/week3_what_is_computation]];
+[[Reduction Strategies and Normal Forms|topics/week3_evaluation_order]];
+[[Unit and its usefulness|topics/week3 unit]];
+[[Combinatory Logic|topics/week3 combinatory logic]];
+[[Homework|exercises/assignment3]]
+
+> Also, by this point you should be able to handle all of *The Little Schemer* except for Chapters 9 and 10. Chapter 9 covers what is going on under the hood with `letrec`, and that will be our topic for next week. You can also read Chapter 4 of Hankin on Combinatory Logic.
+
+> We posted [[answers to Week 2's homework|exercises/assignment2_answers]].
+
+(**Week 4**) Thursday 19 February 2015
+
+> Topics: [[!img images/tabletop_roleplaying.png size="240x240" alt="Hey, no recursing"]]
+[[Yes, recursing|topics/week4_fixed_point_combinators]];
+[[More about fixed point combinators|topics/week4_more_about_fixed_point_combinators]];
+Towards types (in progress);
+[[Homework|exercises/assignment4]]
+
+> Now you can read Sections 3.1 and 6.1 of Hankin; and browse the rest of Hankin Chapter 6, which should look somewhat familiar.
+
+> If you're reading along in the Pierce book, we've now covered much of the material in his Chapters 1-7.
+
+> We posted [[answers to Week 3's homework|exercises/assignment3_answers]].
+
+(**Week 5**) Thursday 26 February 2015
+> Topics:
+[[Simply-typed lambda calculus|topics/week5 simply typed]];
+[[System F|topics/week5 system F]];
+Types in OCaml and Haskell (will be posted someday);
+Practical advice for working with OCaml and/or Haskell (will be posted someday);
+[[Homework|exercises/assignment5]]
+
+> *There is some assigned reading for our next meeting.* This comes in two batches. The first batch consists of [[this footnote|readings/kaplan-plexy.pdf]] from Kaplan's *Demonstratives*. Also recommended, but not mandatory, is [[this selection|readings/king-on-schiffer.pdf]] from Chapter 4 of Jeff King's 2007 book *The Nature and Structure of Content*. The second batch consists of [[this paper|readings/rieppel-beingsthg.pdf]] from Michael Rieppel, a recent Berkeley Philosophy PhD, on Frege's "concept horse" problem. Also recommended, but not mandatory, is [[this selection|readings/king-on-logicism.pdf]] from Chapter 5 of King's book. (It reviews and elaborates his paper "[Designating propositions](http://philpapers.org/rec/KINDP)".)
+
+> If you're interested in the scholarly background on Frege's "concept horse" problem, here is [an entry point](http://philpapers.org/rec/PROWIF).
+
+> If you're reading along in Hankin, you can look at Chapter 7.
+
+> If you're reading along in the Pierce book, the chapters most relevant to this week's discussion are 22 and 23; though for context we also recommend at least Chapters 8, 9, 11, 20, and 29. We don't expect most of you to follow these recommendations now, or even to be comfortable enough yet with the material to be able to. We're providing the pointers as references that some might conceivably pursue now, and others later.
+
+(**Week 6**) Thursday March 5
+
+> We will be discussing the readings posted above.
+
+> Topics: [[Kaplan on Plexy|topics/week6_plexy]]; King on that-clauses and "the proposition that P"; Rieppel on Frege and the concept HORSE
+
+(**Week 7**) Thursday March 12
+
+> *Many of these were updated or first posted on Mon 23 March.*
+
+> Topics: [[Combinatory evaluator|topics/week7_combinatory_evaluator]]; [[Introducing Monads|topics/week7_introducing_monads]]; [[Homework|exercises/assignment7]]; [[Environments and Closures|topics/week7_environments_and_closures]]; [[Untyped lambda evaluator|topics/week7_untyped_evaluator]]
+
+> We posted answers to [[Week 4's homework|exercises/assignment4_answers]] and [[Week 5-6's homework|exercises/assignment5_answers]].
+
+
+(**Week 8**) Thursday March 26
+> Topics: [[Safe division with monads|topics/week8_safe_division_with_monads]]; [[Long but useful ramble|topics/week8_ramble]]
+
+(**Week 9**) Thursday April 2
+> Topics: [[Installing and using the OCaml Juli8 library|/juli8]]; [[Using the OCaml Monad library|/topics/week9_using_the_monad_library]]; the State monad; Programming with mutable state; Using multiple monads together
+
<!--
We've added a [[Monad Library]] for OCaml.
developed in computer science and that linguists and philosophers ought to
know, or may already be unknowingly trying to reinvent.
-Philosphers and linguists tend to reuse the same familiar tools in
+Philosophers and linguists tend to reuse the same familiar tools in
ever more (sometime spectacularly) creative ways. But when your only
hammer is classical logic, every problem looks like modus ponens. In
contrast, computer scientists have invested considerable ingenuity in