1 # Seminar in Semantics / Philosophy of Language #
3 or: **What Philosophers and Linguists Can Learn From Theoretical Computer Science But Didn't Know To Ask**
5 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" and Philosophy calls it "G83.2296"
6 The seminar meets in spring 2015 on Thursdays from 4-7, in
7 the Linguistics building at 10 Washington Place, in room 104 (back of the first floor).
10 One student session will be held every Wednesday from 3-4 on the
11 fourth floor at 10 Washington Place.
20 The goal of this seminar is to introduce concepts and techniques from
21 theoretical computer science and show how they can provide insight
22 into established philosophical and linguistic problems.
24 This is not a seminar about any particular technology or software.
26 Rather, it's about a variety of conceptual/logical ideas that have been
27 developed in computer science and that linguists and philosophers ought to
28 know, or may already be unknowingly trying to reinvent.
30 Philosphers and linguists tend to reuse the same familiar tools in
31 ever more (sometime spectacularly) creative ways. But when your only
32 hammer is classical logic, every problem looks like modus ponens. In
33 contrast, computer scientists have invested considerable ingenuity in
34 studying tool design, and have made remarkable progress.
36 "Why shouldn't I reinvent some idea X for myself? It's intellectually
37 rewarding!" Yes it is, but it also takes time you might have better
38 spent elsewhere. After all, you can get anywhere you want to go by walking, but you can
39 accomplish more with a combination of walking and strategic subway
42 More importantly, the idiosyncrasies of your particular
43 implementation may obscure what's fundamental to the idea you're
44 working with. Your implementation may be buggy in corner cases you
45 didn't think of; it may be incomplete and not trivial to generalize; its
46 connection to existing literature and neighboring issues may go
47 unnoticed. For all these reasons you're better off understanding the
50 The theoretical tools we'll be introducing aren't very familiar to
51 everyday programmers, but they are prominent in academic computer science,
52 especially in the fields of functional programming and type theory.
54 Of necessity, this course will lay a lot of logical groundwork. But throughout
55 we'll be aiming to mix that groundwork with real cases
56 in our home subjects where these tools play central roles.
59 course is to enable you to make these tools your own; to have enough
60 understanding of them to recognize them in use, use them yourself at least
61 in simple ways, and to be able to read more about them when appropriate.
64 Once we get up and running, the central focii of the course will be
65 **continuations**, **types**, and **monads**. One of the on-going themes will
66 concern evaluation order and issues about how computations (inferences,
67 derivations) unfold in (for instance) time. The key analytic technique is to
68 form a static, order-independent model of a dynamic process. We'll be
69 discussing this in much more detail as the course proceeds.
71 The logical systems we'll be looking at include:
73 * the pure/untyped lambda calculus
75 * the simply-typed lambda calculus
76 * polymorphic types with System F
77 * some discussion of dependent types
78 * if time permits, "indeterministic" or "preemptively parallel" computation and linear logic
82 recursion using the Y-combinator
83 evaluation-order stratgies
84 normalizing properties
85 the Curry-Howard isomorphism(s)
86 monads in category theory and computation
89 ## Who Can Participate? ##
91 The course will not presume previous experience with programming. We
92 will, however, discuss concepts embodied in specific programming
93 languages, and we will encourage experimentation with running,
94 modifying, and writing computer programs.
96 The course will not presume lots of mathematical or logical background, either.
97 However, it will demand a certain amount of comfort working with such material; as a result,
98 it will not be especially well-suited to be a first graduate-level course
99 in formal semantics or philosophy of language. If you have concerns about your
100 background, come discuss them with us.
103 This class will count as satisfying the logic requirement for Philosophy
104 PhD students; however if this would be your first or only serious
105 engagement with graduate-level formal work you should consider
106 carefully, and must discuss with us, (1) whether you'll be adequately
107 prepared for this course, and (2) whether you'd be better served by
108 taking a logic course (at a neighboring department, or at NYU next year)
109 with a more canonical syllabus.
112 Faculty and students from outside of NYU Linguistics and Philosophy are welcome
113 to audit, to the extent that this coheres well with the needs of our local
117 ## Recommended Software ##
119 During the course, we'll be encouraging you to try out various things in Scheme
120 and Caml, which are prominent *functional programming languages*. We'll explain
121 what that means during the course.
123 * **Scheme** is one of two major dialects of *Lisp*, which is a large family
124 of programming languages. Scheme
125 is the more clean and minimalistic dialect, and is what's mostly used in
127 Scheme itself has umpteen different "implementations", which share most of
128 their fundamentals, but have slightly different extensions and interact with
129 the operating system differently. One major implementation used to be called
130 PLT Scheme, and has just in the past few weeks changed their name to Racket.
131 This is what we recommend you use. (If you're already using or comfortable with
132 another Scheme implementation, though, there's no compelling reason to switch.)
134 Racket stands to Scheme in something like the relation Firefox stands to HTML.
136 * **Caml** is one of two major dialects of *ML*, which is another large
137 family of programming languages. Caml has only one active implementation,
138 OCaml, developed by the INRIA academic group in France.
140 * Those of you with some programming background may have encountered a third
141 prominent functional programming language, **Haskell**. This is also used a
142 lot in the academic contexts we'll be working through. Its surface syntax
143 differs from Caml, and there are various important things one can do in
144 each of Haskell and Caml that one can't (or can't as easily) do in the
145 other. But these languages also have a lot in common, and if you're
146 familiar with one of them, it's not difficult to move between it and the
150 <a name=installing></a>
151 [[How to get the programming languages running on your computer]]
153 [[Family tree of functional programming languages]]
155 [[Translating between OCaml Scheme and Haskell]]
157 ## What is Functional Programming? ##
159 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.
161 Read more about the [uptake of Haskell](http://steve-yegge.blogspot.com/2010/12/haskell-researchers-announce-discovery.html) among programmers in the street.
164 ## Recommended Books ##
166 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.
168 * *An Introduction to Lambda Calculi for Computer Scientists*, by Chris
169 Hankin, currently $17 on
170 [Amazon](http://www.amazon.com/dp/0954300653).
172 * (Another good book covering the same ground as the Hankin book, but
173 more thoroughly, and in a more mathematical style, is *Lambda-Calculus and Combinators:
174 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
175 both the Hankin book and this book, you'll notice the authors made some different
176 terminological/notational choices. At first, this makes comprehension slightly slower,
177 but in the long run it's helpful because it makes the arbitrariness of those choices more salient.)
179 * (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.)
181 * *The Little Schemer, Fourth Edition*, by Daniel P. Friedman and Matthias
182 Felleisen, currently $23 on [Amazon](http://www.amazon.com/exec/obidos/ASIN/0262560992).
183 This is a classic text introducing the gentle art of programming, using the
184 functional programming language Scheme. Many people love this book, but it has
185 an unusual dialog format that is not to everybody's taste. **Of particular
186 interest for this course** is the explanation of the Y combinator, available as
187 a free sample chapter [at the MIT Press web page for the
188 book](http://www.ccs.neu.edu/home/matthias/BTLS/).
190 * *The Seasoned Schemer*, also by Daniel P. Friedman and Matthias Felleisen, currently $28
191 on [Amazon](http://www.amazon.com/Seasoned-Schemer-Daniel-P-Friedman/dp/026256100X)
193 * *The Little MLer*, by Matthias Felleisen and Daniel P. Friedman, currently $27
194 on [Amazon](http://www.amazon.com/Little-MLer-Matthias-Felleisen/dp/026256114X).
195 This covers some of the same introductory ground as The Little Schemer, but
196 this time in ML. It uses another dialect of ML (called SML), instead of OCaml, but there are only
197 superficial syntactic differences between these languages. [Here's a translation
198 manual between them](http://www.mpi-sws.org/~rossberg/sml-vs-ocaml.html).
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