XGitUrl: http://lambda.jimpryor.net/git/gitweb.cgi?p=lambda.git;a=blobdiff_plain;f=index.mdwn;h=cc974701f8221e094984d9ceb7bff369fced560e;hp=026cdf8f92a4e2cf5be45ccfdf8d979744b66b81;hb=b78913233fb5db8dc92cf8359d823c518a257a84;hpb=af1825cf01346729dc1fd3d4f0c4deb4157b1946
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+++ b/index.mdwn
@@ 6,41 +6,38 @@ This course is cotaught by [Chris Barker](http://homepages.nyu.edu/~cb125/) and
The seminar meets in spring 2015 on Thursdays from 4 until a bit before 7 (with a short break in the middle), in
the Linguistics building at 10 Washington Place, in room 103 (front of the first floor).

+One student session to discuss homeworks will be held every Wednesday from 56, in Linguistics room 104 (back of the first floor).
+## [[Index of Main Contentcontent]] (lecture notes and more) ##
+
+## [[Offsite Readingsreadings]] ##
## Announcements ##
+* [[Untyped lambda calculus evaluatorcode/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 , 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.
+


* Here is information about [[How to get the programming languages running on your computer]].

* Here are Lecture notes for [[Week1]]; [[Assignment1]]. (*Lecture notes will be posted soon.*)
+we'll be doing the next week. It's expected you'll have made at least a serious start on that
+week's homework (due the following day) before the session.
 > Topics: Basics of Functional Programming
+* Here is information about [[How to get the programming languages running on your computerinstalling]]. If those instructions seem overwhelming, note that it should be possible to do a lot of this course using only demonstration versions of these languages [[that run in your web browserbrowser]].
* Henceforth, unless we say otherwise, every homework will be "due" by
Wednesday morning after the Thursday seminar in which we refer to it.
@@ 74,6 +71,72 @@ what is difficult, what you tried, why what you tried didn't work, and
what you think you need in order to solve the problem.
+
+
+(**Week 1**) Thursday 29 Jan 2015
+
+> Topics:
+[[Order in programming languages and natural languagetopics/week1 order]];
+[[Introduction to functional programmingtopics/week1 kapulet intro]];
+[[Homeworkexercises/assignment1]];
+[[Advanced notestopics/week1 kapulet advanced]]
+
+(**Intermezzo**)
+> Help on [[learning Scheme]], [[OCamllearning OCaml]], and [[Haskelllearning Haskell]];
+The [[differences between our madeup language and Scheme, OCaml, and Haskellrosetta1]];
+[[What do words like "interpreter" and "compiler" mean?ecosystem]] (in progress)
+
+(**[[Lambda Evaluatorcode/lambda evaluator]]**) Usable in your browser. It can help you check whether your answer to some of the (upcoming) homework questions works correctly.
+
+
+(**Week 2**) Thursday 5 February 2015
+> Topics:
+[[Intro to the Lambda Calculustopics/week2 lambda intro]];
+[[Advanced notestopics/week2 lambda advanced]];
+[[Encoding Booleans, Tuples, Lists, and Numberstopics/week2 encodings]];
+[[Homeworkexercises/assignment2]]
+
+> Also, if you're reading the Hankin book, try reading Chapters 13. 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 homeworkexercises/assignment1_answers]].
+
+(**Week 3**) Thursday 12 February 2015
+*We will continue to develop these notes over the next few days.*
+
+> Topics:
+[[Arithmetic with Church numberstopics/week3_church_arithmetic]];
+[[More on Liststopics/week3 lists]] (expanded on Sunday);
+[[What is computation?topics/week3_what_is_computation]];
+Reduction Strategies and Normal Forms (in progress);
+[[Unit and its usefulnesstopics/week3 unit]] (posted on Wednesday);
+[[Combinatory Logictopics/week3 combinatory logic]] (revised on Monday and Tuesday);
+[[Homeworkexercises/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 homeworkexercises/assignment2_answers]].
+
+(**Week 4**) Thursday 19 February 2015
+
+> Topics: [[!img images/tabletop_roleplaying.png size="240x240" alt="Hey, no recursing"]]
+[[Yes, recursingtopics/week4_fixed_point_combinators]];
+[[More about fixed point combinatorstopics/week4_more_about_fixed_point_combinators]];
+Towards types (in progress);
+[[Homeworkexercises/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.
+
+> We posted [[answers to Week 3's homeworkexercises/assignment3_answers]].
+
+
+
+
+
## Course Overview ##
The overarching goal of this seminar is to introduce concepts and techniques from
@@ 118,7 +181,10 @@ course is to enable you to make these tools your own; to have enough
understanding of them to recognize them in use, use them yourself at least
in simple ways, and to be able to read more about them when appropriate.
[[More about the topics and larger themes of the course]]
+"Computer Science is no more about computers than astronomy is about telescopes."  [E. W. Dijkstra](https://en.wikipedia.org/wiki/Edsger_W._Dijkstra) (or Hal Abelson, or Michael Fellows; the quote's origins are murky)
+
+
+[[More about the topics and larger themes of the courseoverview]]
## Who Can Participate? ##
@@ 174,8 +240,10 @@ strictly exclusive. The labels are better thought of as concerning different
of the extent to which they emphasize, and are designed around those idioms. Languages like Python and JavaScript are sometimes themselves
described as "more functional" than other languages, like C.

In any case, here is some more context for the three languages we will be focusing on.
+In any case, here is
+
+[[How to get the programming languages running on your computerinstalling]].
+And here is some more context for the three languages we will be focusing on:
* **Scheme** is one of two or three major dialects of *Lisp*, which is a large family
of programming languages. Scheme
@@ 187,11 +255,21 @@ the operating system differently. One major implementation is called Racket,
and that is what we recommend you use. If you're already using or comfortable with
another Scheme implementation, though, there's no compelling reason to switch.
 Racket stands to Scheme in something like the relation Firefox stands to HTML.
+ Another good Scheme implementation is Chicken. For our purposes, this is in some
+respects superior to Racket, and in other respects inferior.
+
+ Racket and Chicken stand to Scheme in something like the relation Firefox stands to HTML.
 (Wikipedia on [Lisp](http://en.wikipedia.org/wiki/Lisp_%28programming_language%29),
+ (Wikipedia on
+[Lisp](http://en.wikipedia.org/wiki/Lisp_%28programming_language%29),
[Scheme](http://en.wikipedia.org/wiki/Scheme_%28programming_language%29),
and [Racket](http://en.wikipedia.org/wiki/Racket_%28programming_language%29).)
+[Racket](http://en.wikipedia.org/wiki/Racket_%28programming_language%29), and
+[Chicken](http://en.wikipedia.org/wiki/CHICKEN_%28Scheme_implementation%29).)
+ (Help on [[Learning Scheme]])
* **Caml** is one of two major dialects of *ML*, which is another large
family of programming languages. Caml has only one active "implementation",
@@ 199,13 +277,14 @@ OCaml, developed by the INRIA academic group in France. Sometimes we may refer t
more generally; but you can assume that what we're talking about always works more
specifically in OCaml.
 (Wikipedia on [ML](http://en.wikipedia.org/wiki/ML_%28programming_language%29),
[Caml](http://en.wikipedia.org/wiki/Caml),
and [OCaml](http://en.wikipedia.org/wiki/OCaml).)
+ (Wikipedia on
+[ML](http://en.wikipedia.org/wiki/ML_%28programming_language%29),
+[Caml](http://en.wikipedia.org/wiki/Caml), and
+[OCaml](http://en.wikipedia.org/wiki/OCaml).)
+ (Help on [[Learning OCaml]])
* Those of you with some programming background may have encountered a third
prominent functional programming language, **Haskell**. This is also used a
+* **Haskell** is also used a
lot in the academic contexts we'll be working through. Its surface syntax
differs from Caml, and there are various important things one can do in
each of Haskell and Caml that one can't (or can't as easily) do in the
@@ 213,11 +292,19 @@ other. But these languages also have *a lot* in common, and if you're
familiar with one of them, it's generally not hard to move between it and the
other.
 (Wikipedia on [Haskell](http://en.wikipedia.org/wiki/Haskell_%28programming_language%29).)
+ Like Scheme, Haskell has a couple of different implementations. The
+dominant one, and the one we recommend you install, is called GHC, short
+for "Glasgow Haskell Compiler".
+ (Wikipedia on
+[Haskell](http://en.wikipedia.org/wiki/Haskell_%28programming_language%29) and
+[GHC](https://en.wikipedia.org/wiki/Glasgow_Haskell_Compiler).)
+ (Help on [[Learning Haskell]])
+
+

[[How to get the programming languages running on your computer]]
## Recommended Books ##
@@ 251,6 +338,20 @@ comfortable with OCaml (or with Haskell) than with Scheme might consider
working through this book instead of The Little Schemer. For the rest of you,
or those of you who *want* practice with Scheme, go with The Little Schemer.
+* *The Haskell Road to Logic, Math and Programming*, by Kees Doets and Jan van Eijck, currently $22 on [Amazon](http://www.amazon.com/dp/0954300696) is a textbook teaching the parts of math and logic we cover in the first few weeks of Logic for Philosophers. (Notions like validity, proof theory for predicate logic, sets, sequences, relations, functions, inductive proofs and recursive definitions, and so on.) The math here should be accessible and familiar to all of you. What is novel about this book is that it integrates the exposition of these notions with a training in (part of) Haskell. It only covers the rudiments of Haskell's type system, and doesn't cover monads; but if you wanted to review this material and become comfortable with core pieces of Haskell in the process, this could be a good read.
+(The book also seems to be available online [here](http://flditwww.cs.unidortmund.de/~peter/PS07/HR.pdf).)
+
+
+The rest of these are a bit more advanced, and are also looser suggestions:
+
+* *Computational Semantics with Functional Programming*, by Jan van Eijck and Christina Unger, currently $42 on [Amazon](http://www.amazon.com/dp/0521757606). We own this but haven't read it yet. It *looks* like it's doing the same kind of thing this seminar aims to do: exploring how natural language meanings can be understood to be "computed". The text uses Haskell, and is aimed at linguists and philosophers as well as computer scientists. Definitely worth a look.
+
+
* Another good book covering the same ground as the Hankin book, but
more thoroughly, and in a more mathematical style, is *LambdaCalculus and Combinators:
an Introduction*, by J. Roger Hindley and Jonathan P. Seldin, currently $74 hardback / $65 kindle on [Amazon](http://www.amazon.com/dp/0521898854).
@@ 261,7 +362,10 @@ If you choose to read both the Hankin book and this book, you'll notice the auth
terminological/notational choices. At first, this makes comprehension slightly slower,
but in the long run it's helpful because it makes the arbitrariness of those choices more salient.
* Another good book, covering some of the same ground as the Hankin, and the Hindley & Seldin, but delving deeper into typed lambda calculi, is *Types and Programming Languages*, by Benjamin Pierce, currently $77 hardback / $68 kindle on [Amazon](http://www.amazon.com/dp/0262162091). This book has many examples in OCaml.
+
+* Another good book, covering a bit of the same ground as the Hankin and the Hindley & Seldin, but focusing especially on typed lambda calculi, is *Types and Programming Languages*, by Benjamin Pierce, currently $77 hardback / $68 kindle on [Amazon](http://www.amazon.com/dp/0262162091). This book has many examples in OCaml. It seems to be the standard textbook for CS students learning type theory.
+
+* The next two books focus on the formal semantics of typed programming languages, both in the "denotational" form that most closely corresponds to what we mean by semantics, and in the "operational" form very often used in CS. These are: *The Formal Semantics of Programming Languages*, by Glynn Winskel, currently $38 on [Amazon](http://www.amazon.com/dp/0262731037), and *Semantics of Programming Languages*, by Carl Gunter, currently $41 on [Amazon](http://www.amazon.com/dp/0262071436).
