dvanhorn @ λ-calcul.us

Photos from TFP 2010

Tuesday, June 8, 2010

Some photos from TFP 2010, Norman, Oklahoma.

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Robin Milner: The Elegant Pragmatist

Tuesday, June 8, 2010

Turing award winner and programming language trailblazer, Robin Milner, who recently passed away, has a cover story in the latest Communications of the ACM.

A man of modest background and quiet brilliance, Milner made ground-breaking contributions to the fields of verification, programming languages, and concurrency. He was born in 1934 near Plymouth, England, and won scholarships to Eton—where he developed an enduring love of math as well as a prodigious work ethic—and King’s College, Cambridge. It was during his time at Cambridge that Milner was introduced to programming, though the subject didn’t interest him initially. “I regarded programming as really rather inelegant,” he recalled in an interview in 2001 with Martin Berger, a professor at the University of Sussex. “So I resolved that I would never go near a computer in my life.”

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What’s the Racket?

Monday, June 7, 2010

Racket, the system formerly known as PLT Scheme, has just been released.

PLT is happy to announce the release of Racket, available from

http://racket-lang.org/

With Racket, you can script command shells and web servers; you can quickly prototype animations and complex GUIs; regexps and threads are here to serve you. To organize your systems, you can mix and match classes, modules or components. Best of all, you start without writing down types. If you later wish to turn your script into a program, equip your Racket modules with explicit type declarations as you wish. And Racket doesn’t just come as a typed variant; you can also write your modules in a purely functional and lazy dialect.

Racket comes in so many flavors because Racket is much more than a standard scripting language or a plain programming language. Racket supports language extensibility to an unequaled degree. A Racket programmer knows that making up a new language is as easy as writing a new library.

To help you start quickly, Racket includes batteries in all shapes and sizes, most importantly, extensive documentation and all kinds of libraries.

Racket occupies a unique position between research and practice. It inherits many major ideas from language research, among them type safety (when the type system says that x is a number, then at runtime it always is a number) and memory safety (when some memory is reclaimed by the garbage collector it is impossible to still have a reference to it). At the same time, user demand governs rigid adherence to purely theoretical principles.

Racket, formerly PLT Scheme, is a product of over 15 years of development. Although Racket starts with a mature software base and an established user community, its new name reflects our view that this is just the beginning of Racket’s evolution.

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Fun with Unicode and delimited continuations

Thursday, June 3, 2010

Doug Orleans’ cute program to compute roots of quadratic equations:

(define (± x y)
  (shift k (values (k (+ x y)) (k (- x y)))))

(define (quadratic-formula-roots a b c)
  (reset (/ (± (- b) (√ (- (² b) (* 4 a c))))
	    (* 2 a))))

Filed in Poetry, Scheme | Comments (0)

Evaluating Call By Need on the Control Stack

Tuesday, May 18, 2010

New paper from Stephen Chang, David Van Horn, and Matthias Felleisen, appearing at Trends in Functional Programming 2010: Evaluating Call By Need on the Control Stack.

Abstract:

Ariola and Felleisen’s call-by-need λ-calculus replaces a variable occurrence with its value at the last possible moment. To support this gradual notion of substitution, function applications—once established—are never discharged. In this paper we show how to translate this notion of reduction into an abstract machine that resolves variable references via the control stack. In particular, the machine uses the static address of a variable occurrence to extract its current value from the dynamic control stack.

PDF

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First you curse…

Wednesday, March 31, 2010

…then you recurse: http://www.google.com/search?q=recursion.

Filed in Paradox, Stupid | Comments (0)

PhD and Postdoc positions: Functional Programming and Automatic Differentiation

Thursday, March 4, 2010

Barak Pearlmutter is looking for PhD students and postdocs to work on functional programming and automatic differentiation.

I’m looking for PhD students and postdocs interested in working on an
elegant combination of functional programming and big-iron style
numeric computing. Blurb below. If you know anyone good who might be
interested, I’d be grateful if you’d pass this along.

Sounds fun!

Functional Programming and Automatic Differentiation

PhD Studentships
Postdoctoral Positions

We are adding exact first-class derivative calculation operators
(Automatic Differentiation or AD) to the lambda calculus, and
embodying the combination into a production-quality optimising
compiler. Our research prototype compiler generates object code
competitive with the fastest current systems, which are based on
FORTRAN. We are seeking PhD students and postdocs with interest and
experience in relevant areas: programming language theory, numeric
computing/numeric linear algebra, or differential geometry; and a
burning drive to help lift big iron numeric computing out of the 1960s
and into a newer higher order. Specific sub-projects include:
compiler and numeric programming environment construction; writing,
simplifying, and generalising numeric algorithms through the use of AD
operators; and associated type/lambda calculus/PLT/real computation
issues.

The project headquarters will be in the Hamilton Institute, NUI
Maynooth, Ireland, http://www.hamilton.ie/.

Applications to:
“Barak A. Pearlmutter”

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NJPLS, NEPLS, TFP, WSFP, ICFP

Sunday, February 28, 2010

This should keep you busy.

NJPLS:

The next NJPLS will be on Friday April 9 at Stevens Institute of
Technology. If you would like to present a cool idea to the NJPLS
community, please send me your talk request by March 17. Please send me
an email with your talk title and abstract. All topics in programming
languages and systems are welcome.

Stevens is located in Hoboken, just across the Hudson river from midtown
Manhattan.

Information about past NJPLS events can be found at http://www.njpls.org/

NEPLS:

This is an early announcement of the upcoming Spring 2010 NEPLS
meeting. It will take place on

April 29, Thursday, 2010

at Yale University. Please mark it in your calendars! For additional
information about NEPLS, please consult the Web page

http://www.nepls.org/

The speaker selection committee welcomes suggestions — you may
propose either yourself, or someone else whom the committee will
contact. To propose speakers, send mail to

talks@nepls.org

We will send another message to solicit talks in early March.

(Replying to this message will work in most cases, but some
mailing lists thwart the simplicity of this plan by masquerading as
your correspondents — please check before sending.)

Additional event information will appear on the Web in due course.

TFP:

TFP 2010: 11th SYMPOSIUM ON TRENDS IN FUNCTIONAL PROGRAMMING
May 17-19, 2010
University of Oklahoma http://www.cs.ou.edu/tfp2010/

TFP 2010 is an international forum for researchers with interests in any aspect of functional programming.

SUBMISSION and REGISTRATION DEADLINES
April 2: Submission deadline
April 16: Early registration deadline ($350, $200 for students)
May 7: Late registration deadline ($425)
May 17-19: TFP Symposium

POST-SYMPOSIUM PROCEEDINGS
Springer series: Lecture Notes in Computer Science

Details about the event schedule, symposium scope, submissions, and registration may be found on the symposium website (web browser key “tfp 2010″). http://www.cs.ou.edu/tfp2010/

Submitted papers and extended abstracts are reviewed for presentation at the symposium, and a formal refereeing process after the symposium selects the best presentations for publication the Springer series, Lecture Notes in Computer Science.

We invite you to participate in TFP 2010.
– Rex Page, University of Oklahoma, Program Chair
– Viktia Zs and Zolt Horvath, Ev Lord University, Symposium Co-Chairs
Sponsors: Erlang Solutions Ltd and The University of Oklahoma

WSFP:

Call for Papers
2010 Workshop on Scheme and Functional Programming
Montréal, Québec, Canada
Saturday and Sunday August 21-22, 2010
http://www.iro.umontreal.ca/~sfp2010
Important Dates
Submission: 11 June 2010
Notification: 2 July 2010
Final papers due: 23 July 2010

All deadlines are at 14:00 UTC.

ICFP:

ICFP 2010: International Conference on Functional Programming

Baltimore, Maryland, 27 — 29 September 2010

http://www.icfpconference.org/icfp2010

Important Dates (at 14:00 UTC)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Submission: 2 April 2010
Author response: 24 — 25 May 2010
Notification: 7 June 2010
Final papers due: 12 July 2010

Filed in Announce | Comments (0)

Oregon PL School: Logic, Languages, Compilation, and Verification

Monday, February 8, 2010

University of Oregon is hosting another Oregon Programming Languages Summer School this June. This year’s topic is Logic, Languages, Compilation, and Verification:

Everyday life and critical aspects of our economy, defense, and government depend on software, and software, in turn, depends on high-level programming languages and their efficient implementations. Ever since Fortran and its automatic compiler in the late 50s, language implementation techniques have been central to computer science, and have relied on well-defined theoretical contributions and central principles. The focus of this summer school is the mix or interplay of theory and practice in language implementation mechanisms, such as compilers or run-time systems. The main aim of this summer school is to enable participants to conduct research in the area, thereby contributing to improved software.

By presenting a range of material, from foundational work on language implementation theory, to advanced techniques based on cutting-edge research, to experience with applying the theory, we will provide a unique opportunity for participants to understand the current research landscape. Lectures will include discussions of core ideas such as abstract interpretation, static program analyses, and intermediate representations (e.g., continuations) and their connection to language semantics. The lectures will explore how these ideas can be adapted to yield efficient and general programming language implementations, at the level of a compiler or a run-time system.

At all times, material will be presented at a tutorial level that will help graduate students and researchers from academia or industry understand the critical issues and open problems confronting the field. We hope that students will be able to apply what they learn at the school in their own research. We believe that by doing so the school will have a broad impact on the next generation of programming language, compiler and software engineering researchers in industry and academia.

The course is open to anyone interested. Prerequisites are knowledge of programming language implementation (at the level usually covered in undergraduate classes on programming languages or compilers) as well as general knowledge of programming languages at the level provided by an undergraduate survey course. Our primary target group is first- or second-year graduate students. We also expect attendance by faculty members who would like to conduct research on this topic or introduce new courses at their universities.

The line-up of speakers looks outstanding. Having been to a couple of these summer schools already, I can say they are a great way to immerse yourself in an area of the field. I highly recommend it for PhD students looking for a topic to work on, but also more senior researchers can use the school to become familiar with a body of work outside of their immediate area.

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CACM: Type Theory Comes of Age

Tuesday, February 2, 2010

The current issue of CACM has an article on type theory:

When the philosopher Bertrand Russell invented type theory at the beginning of the 20th century, he could hardly have imagined that his solution to a simple logic paradox—defining the set of all sets not in themselves—would one day shape the trajectory of 21st century computer science.

It is riddled with misconceptions, errors, and self-aggrandizement. It does us the great disservice of conflating (dynamic) memory safety and (static) type safety, and has whoppers like “A type system ensures the correct behavior of any program routine by enforcing a set of predetermined behaviors,” which is just false. But hey, ra-ra types! No?

Filed in Types | Comments (0)

Photos from TFP 2010

Robin Milner: The Elegant Pragmatist

What’s the Racket?

Fun with Unicode and delimited continuations

Evaluating Call By Need on the Control Stack

First you curse…

PhD and Postdoc positions: Functional Programming and Automatic Differentiation

NJPLS, NEPLS, TFP, WSFP, ICFP

Oregon PL School: Logic, Languages, Compilation, and Verification

CACM: Type Theory Comes of Age

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