or: **What Philosophers and Linguists Can Learn From Theoretical Computer Science But Didn't Know To Ask**
-This course is co-taught by [Chris Barker](http://homepages.nyu.edu/~cb125/) and [Jim Pryor](http://www.jimpryor.net/). Linguistics calls it "G61.3340-002" and Philosophy calls it "G83.2296-001."
-The seminar meets on Mondays from 4-6, in
-the Linguistics building at 10 Washington Place, in room 104 (back of the first floor).
+This course is co-taught by [Chris Barker](http://homepages.nyu.edu/~cb125/) and [Jim Pryor](http://www.jimpryor.net/). Linguistics calls it "LING-GA 3340" and Philosophy calls it "PHIL-GA 2296".
+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 will be held every Wednesday from 3-4 on the
fourth floor at 10 Washington Place.
+-->
-## Announcements ##
-
-* This is the time of the semester when some people start slipping
- behind with the homework. Don't.
-
-[[Older Announcements]]
-
-##[[Lambda Evaluator]]##
-
-Usable in your browser. It can help you check whether your answer to some of
-the homework questions works correctly.
-
-There is also now a [library](/lambda_library) of lambda-calculus
-arithmetical and list operations, some relatively advanced.
-
-
-## Lecture Notes and Assignments ##
-
-(13 Sept) Lecture notes for [[Week1]]; [[Assignment1]].
-
-> Topics: [[Applications]], including [[Damn]]; Basics of Lambda Calculus; Comparing Different Languages
-
-(20 Sept) Lecture notes for [[Week2]]; [[Assignment2]].
-
-> Topics: Reduction and Convertibility; Combinators; Evaluation Strategies and Normalization; Decidability; [[Lists and Numbers]]
-
-(27 Sept) Lecture notes for [[Week3]]; [[Assignment3]];
-an evaluator with the definitions used for homework 3
-preloaded is available at [[assignment 3 evaluator]].
-
-> Topics: [[Evaluation Order]]; Recursion with Fixed Point Combinators
-
-(4 Oct) Lecture notes for [[Week4]]; [[Assignment4]].
-
-> Topics: More on Fixed Points; Sets; Aborting List Traversals; [[Implementing Trees]]
-
-
-(18 Oct, 25 Oct) Lecture notes for [[Week5]] and [[Week6]]; [[Assignment5]].
-
-> Topics: Types, Polymorphism, Unit and Bottom
-
-(1 Nov) Lecture notes for [[Week7]]; [[Assignment6]].
-
-> Topics: Monads; [[Reader Monad for Variable Binding]]; [[Reader Monad for Intensionality]]
-
-(8 Nov) Lecture notes for [[Week8]].
-
-> Topics: Reader Monad for Jacobson's Variable-Free Semantics
-
-(15 Nov) Lecture notes for [[Week9]]; [[Assignment7]]. Everyone auditing in the class is encouraged to do this assignment, or at least work through the substantial "hints".
-
-> Topics: Mutable Variables; Passing by Reference
-
-
-[[Upcoming topics]]
-
-[[Advanced Topics]]
-
-> Topics: Version 4 lists, Monads in Category Theory
-
-##Scheme and OCaml##
-
-See [below](#installing) for how to get the programming languages running on your computer.
-* Links for help [[learning Scheme]]
+## Announcements ##
-* Links for help [[learning OCaml]]
+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.
+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
+the text and links there haven't been updated. And/or get started on installing the software and ordering some of the books.
-##[[Offsite Reading]]##
+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.
-There's lots of links here already to tutorials and encyclopedia entries about many of the notions we'll be dealing with.
+As we mentioned in class, we're also going to schedule a session to discuss the weekly homeworks. If you'd like to participate in this, please complete [this Doodle poll](http://doodle.com/7xrf4w8xq4i9e5za). It asks when you are available on Tuesdays and Wednesdays.
+Here is information about [[How to get the programming languages running on your computer]].
## Course Overview ##
-The goal of this seminar is to introduce concepts and techniques from
+The overarching goal of this seminar is to introduce concepts and techniques from
theoretical computer science and show how they can provide insight
into established philosophical and linguistic problems.
This is not a seminar about any particular technology or software.
+
Rather, it's about a variety of conceptual/logical ideas that have been
developed in computer science and that linguists and philosophers ought to
know, or may already be unknowingly trying to reinvent.
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
-studying tool design, and have made remarkable progress.
+studying the design of their conceptual tools (among other things), and they've made much progress that we can benefit from.
"Why shouldn't I reinvent some idea X for myself? It's intellectually
rewarding!" Yes it is, but it also takes time you might have better
unnoticed. For all these reasons you're better off understanding the
state of the art.
-The theoretical tools we'll be introducing aren't very familiar to
+The theoretical tools we'll be introducing aren't part of the diet of most
everyday programmers, but they are prominent in academic computer science,
especially in the fields of functional programming and type theory.
Of necessity, this course will lay a lot of logical groundwork. But throughout
we'll be aiming to mix that groundwork with real cases
-in our home subjects where these tools play central roles. Our aim for the
+in our home subjects where these tools can (or already do, covertly) play central roles.
+
+Our aim for the
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.
-Once we get up and running, the central focii of the course will be
-**continuations**, **types**, and **monads**. One of the on-going themes will
-concern evaluation order and issues about how computations (inferences,
-derivations) unfold in (for instance) time. The key analytic technique is to
-form a static, order-independent model of a dynamic process. We'll be
-discussing this in much more detail as the course proceeds.
-
-The logical systems we'll be looking at include:
-
-* the pure/untyped lambda calculus
-* combinatorial logic
-* the simply-typed lambda calculus
-* polymorphic types with System F
-* some discussion of dependent types
-* if time permits, "indeterministic" or "preemptively parallel" computation and linear logic
+[[More about the topics and larger themes of the course]]
-<!--
-Other keywords:
- recursion using the Y-combinator
- evaluation-order stratgies
- normalizing properties
- the Curry-Howard isomorphism(s)
- monads in category theory and computation
--->
-
## Who Can Participate? ##
The course will not presume previous experience with programming. We
in formal semantics or philosophy of language. If you have concerns about your
background, come discuss them with us.
+<!--
This class will count as satisfying the logic requirement for Philosophy
PhD students; however if this would be your first or only serious
engagement with graduate-level formal work you should consider
prepared for this course, and (2) whether you'd be better served by
taking a logic course (at a neighboring department, or at NYU next year)
with a more canonical syllabus.
-
+-->
Faculty and students from outside of NYU Linguistics and Philosophy are welcome
to audit, to the extent that this coheres well with the needs of our local
## Recommended Software ##
During the course, we'll be encouraging you to try out various things in Scheme
-and Caml, which are prominent *functional programming languages*. We'll explain
-what that means during the course.
+and OCaml. Occasionally we will also make remarks about Haskell. All three of these
+are prominent *functional programming languages*. The term "functional" here means they have
+a special concern with functions, not just that they aren't broken. But what precisely is
+meant by "functional" is somewhat fuzzy and even its various precisifications take some
+time to explain. We'll get clearer on this during the course. Another term used roughly the same as "functional"
+is "declarative." At a first pass, "functional" or "declarative" programming is primarily focused on complex
+expressions that get computationally evaluated to some (usually simpler) result. In class I gave the examples
+of `1+2` (which gets evaluated in arithmetic to 3), `1+2 < 5` (which gets evaluated in arithmetic to 'true), and `1`
+(which gets evaluated in arithmetic to 1). Also Google search strings, which get evaluated by Google servers to a
+list of links.
+
+The dominant contrasting class of programming languages (the great majority of what's used
+in industry) are called "imperatival" languages, meaning they have more to do with following a sequence of commands (what we
+called in class "side-effects", though sometimes what they're *alongside* is not that interesting, and all the focus is instead
+on the effect). Programming languages like C and Python and JavaScript and so on are all of this sort.
+
+In fact, nothing that gets marketed as a "programming language" is really completely 100% functional/declarative, and even the
+imperatival languages will have purely functional fragments (they evaluate `1+2` to 3, also). So these labels are really
+more about *styles* or *idioms* of programming, and languages like Scheme and OCaml and especially Haskell get called "functional languages" because
+of the extent to which they emphasize, and are designed around those idioms. Even languages like Python and JavaScript are sometimes
+described as "more functional" than some other languages. The language C is about as non-functional as you can get.
* **Scheme** is one of two major dialects of *Lisp*, which is a large family
of programming languages. Scheme
academic circles.
Scheme itself has umpteen different "implementations", which share most of
their fundamentals, but have slightly different extensions and interact with
-the operating system differently. One major implementation used to be called
-PLT Scheme, and has just in the past few weeks changed their name to Racket.
-This 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.)
+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.
+ (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).)
+
* **Caml** is one of two major dialects of *ML*, which is another large
-family of programming languages. Caml has only one active implementation,
-OCaml, developed by the INRIA academic group in France.
+family of programming languages. Caml has only one active "implementation",
+OCaml, developed by the INRIA academic group in France. Sometimes we may refer to Caml or ML
+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).)
+
* Those of you with some programming background may have encountered a third
prominent functional programming language, **Haskell**. This is also used a
familiar with one of them, it's not difficult to move between it and the
other.
+ (Wikipedia on [Haskell](http://en.wikipedia.org/wiki/Haskell_%28programming_language%29).)
+
+
<a name=installing></a>
[[How to get the programming languages running on your computer]]
+<!--
[[Family tree of functional programming languages]]
+[[Translating between OCaml Scheme and Haskell]]
+
+## What is Functional Programming? ##
+
+Here's a [survey conducted at Microsoft](http://research.microsoft.com/apps/pubs/default.aspx?id=141506) asking programmers what they understand "functional programming" to be. Don't take their responses to be authoritative... this is a just a "man in the street" (seat?) poll.
+
+Read more about the [uptake of Haskell](http://steve-yegge.blogspot.com/2010/12/haskell-researchers-announce-discovery.html) among programmers in the street.
+-->
## Recommended Books ##
-It's not necessary to purchase these for the class. But they are good ways to get a more thorough and solid understanding of some of the more basic conceptual tools we'll be using.
+It's not *mandatory* to purchase these for the class. But they are good ways to get a more thorough and solid understanding of some of the more basic conceptual tools we'll be using. We especially recommend the first three of them.
* *An Introduction to Lambda Calculi for Computer Scientists*, by Chris
-Hankin, currently $17 on
+Hankin, currently $18 paperback on
[Amazon](http://www.amazon.com/dp/0954300653).
-* (Another good book covering the same ground as the Hankin book, but
-more thoroughly, and in a more mathematical style, is *Lambda-Calculus and Combinators:
-an Introduction*, by J. Roger Hindley and Jonathan P. Seldin, currently $52 on [Amazon](http://www.amazon.com/dp/0521898854). If you choose to read
-both the Hankin book and this book, you'll notice the authors made some different
-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 previous two, but also delving much deeper into typed lambda calculi, is *Types and Programming Languages*, by Benjamin Pierce, currently $61 on [Amazon](http://www.amazon.com/dp/0262162091). This book has many examples in OCaml.)
-
* *The Little Schemer, Fourth Edition*, by Daniel P. Friedman and Matthias
-Felleisen, currently $23 on [Amazon](http://www.amazon.com/exec/obidos/ASIN/0262560992).
+Felleisen, currently $29 paperback on [Amazon](http://www.amazon.com/exec/obidos/ASIN/0262560992).
This is a classic text introducing the gentle art of programming, using the
functional programming language Scheme. Many people love this book, but it has
an unusual dialog format that is not to everybody's taste. **Of particular
a free sample chapter [at the MIT Press web page for the
book](http://www.ccs.neu.edu/home/matthias/BTLS/).
-* *The Seasoned Schemer*, also by Daniel P. Friedman and Matthias Felleisen, currently $28
-on [Amazon](http://www.amazon.com/Seasoned-Schemer-Daniel-P-Friedman/dp/026256100X)
+* *The Seasoned Schemer*, also by Daniel P. Friedman and Matthias Felleisen, currently $29 paperback
+on [Amazon](http://www.amazon.com/Seasoned-Schemer-Daniel-P-Friedman/dp/026256100X). This is a sequel to The Little Schemer, and it focuses on mutation and continuations in Scheme. We will be covering those topics in the second half of the course.
-* *The Little MLer*, by Matthias Felleisen and Daniel P. Friedman, currently $27
+* *The Little MLer*, by Matthias Felleisen and Daniel P. Friedman, currently $31 paperback / $29 kindle
on [Amazon](http://www.amazon.com/Little-MLer-Matthias-Felleisen/dp/026256114X).
-This covers some of the same introductory ground as The Little Schemer, but
-this time in ML. It uses another dialect of ML (called SML), instead of OCaml, but there are only
-superficial syntactic differences between these languages. [Here's a translation
-manual between them](http://www.mpi-sws.org/~rossberg/sml-vs-ocaml.html).
+This covers much of the same introductory ground as The Little Schemer, but
+this time in a dialect of ML. It doesn't use OCaml, the dialect we'll be working with, but instead another dialect of ML called SML. The syntactic differences between these languages is slight.
+([Here's a translation manual between them](http://www.mpi-sws.org/~rossberg/sml-vs-ocaml.html).)
+Still, that does add an extra layer of interpretation, and you might as well just use The Little Schemer instead. Those of you who are already more 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.
+
+* Another good book covering the same ground as the Hankin book, but
+more thoroughly, and in a more mathematical style, is *Lambda-Calculus 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).
+This book is substantial and though it doesn't presuppose any specific mathematical background knowledge, it will be a good choice only if you're already comfortable reading advanced math textbooks.
+If you choose to read both the Hankin book and this book, you'll notice the authors made some different
+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.
----