Lambda the Ultimate

Some here will find this discussion on language choice for building an industrial strength poker server to be of interest.

This paper was mentioned here before, but not on the home page.

It deserves to get more attention, since it is quite cool.

Warning: This one isn't for the faint of heart, and uses scary terms like polynomial functors, initial algebras and terminal coalgebras, constructive set theory and more...

I do think that professional tools can help dynamic languages consolidate the ground they've been gaining. And to that end, conventional capabilities -- such as suport for testing, debugging, and version control -- will be prerequisites. But dynamic languages really are different in important ways, and their tools should be as well. It's time for some fresh thinking on this topic, and for some new approaches.

Jon also mentions DSLs, stratified design and Patrick Logan (who used to post here more often, and will be welcomed back should he choose to return...)

Based on the progress I’ve made with FORTRAN, I decided to start another effort at the Computer History Museum to track down source code and documents for the original M.I.T. LISP I/1.5 project. I have made some progress, and am assembling a LISP web site at the Museum to organize and present the materials I’ve collected so far, including:

• LISP 1.5: Assembly listing for IBM 709/7090 standalone system, and another for the CTSS port. Information about various other ports and reimplementations including Univac M-460, Q-32, and Univac 1108.
• PDP-1 Lisp: links to the documentation, source code and simulators
• MacLisp (PDP-6, PDP-10): links to documentatation and source code
• BBN-LISP: the manual for the original PDP-1 version and the Tenex version (coming soon: preliminary specifications for the 940 version)
• etc.

My hope for this project is to provide open online access to as much information as possible for students, historians, and other interested people.

Your comments are welcome (here, at my blog Dusty Decks, or by email. What am I missing? What facts have I gotten wrong? Please help fill in the gaps.

Many people are accustomed to imperative languagues, which include C, C++, Java, Python, and Pascal....For [beginning] computer science students,...Haskell is weird and obtuse....This tutorial assumes that the reader is familiar [only] with C/C++, Python, Java, or Pascal. I am writing for you because it seems that no other tutorial was written to help students overcome the difficulty of moving from C/C++, Java, and the like to Haskell.

I write this assuming that you have checked out...the Gentle Introduction to Haskell, but...still don't understand what's going on....

Haskell is not 'a little different,' and will not 'take a little time.' It is very different and you cannot simply pick it up, although I hope that this tutorial will help.

If you play around with Haskell, do not merely write toy programs. Simple problems will not take advantage of Haskell's power. Its power shines mostly clearly when you...attack difficult tasks....Haskell's tools...dramatically simplify your code....

I am going to put many pauses in this tutorial because learning Haskell hurt a lot, at least for me. I needed breaks, and my brain hurt while I was trying to understand....

Now I'm working on a video game in Haskell...and we've written a short tutorial...on HOpenGL....

Haskell has both more flexibility and more control than most languages. Nothing that I know of beats C's control, but Haskell has everything C does unless you need to control specific bytes in memory. So I call Haskell powerful, rather than just 'good.'

I wrote this tutorial because Haskell was very hard for me to learn, but now I love it...."Haskell is hard!" "You can't write code the way I know how!" "My brain hurts!" "There aren't any good references!" That's what I said when I was in college. There were good references, but they didn't cover the real problem: coders know C.

New explorers might enjoy Eclipse IDE support (version 3.1M7 or later only). Old hands might help improve it.

Haskell compiles to C (cf. JHC) and machine code.

Parameterized Unit Tests. Nikolai Tillmann; Wolfram Schulte; Wolfgang Grieskamp

Parameterized unit tests extend the current industry practice of using closed unit tests defined as parameterless methods. Parameterized unit tests separate two concerns: 1) They specify the external behavior of the involved methods for all possible test arguments. 2) Test cases can be re-obtained as traditional closed unit tests by instantiating the parameterized unit tests. Symbolic execution and constraint solving can be used to automatically choose a minimal set of inputs that exercise a parameterized unit test with respect to possible code paths of the implementation. In addition, parameterized unit tests can be used as symbolic summaries which allows symbolic execution to scale for arbitrary abstraction levels. We have developed a prototype tool which computes test cases from parameterized unit tests; it is integrated into the forthcoming Visual Studio Team System product. We report on its first use to test parts of the .NET base class library.

By adding parameters the authors turn a closed unit test into a universally quantified conditional axiom that must hold for all inputs under specified assumptions. Adding parameters improves the expressiveness of unit cases, at the expense of not providing concrete test cases. Symbolic execution is used to automatically find the set of parameters that have to be tested.

This seems like an interesting approach to unifying unit testing and algebraic specifications.

Having just got back from the Reynoldsfest at MFPS, where part of the emphasis was on encouraging folk to look at Reynolds work, let me write down some of what was recommended.

My personal favorites:
Definitional Interpreters (this one changed my life when I was a graduate student)
Gedanken
Towards a Theory of Type Structure
Types, Abstraction and Parametric Polymorphism
The Essence of Algol
Syntactic Control of Interference
Three Approaches to Type Structure (tutorial)
The Discoveries of Continuations (history)

Some papers recommended by others:
The Craft of Programming (recommended by Cliff Jones)
Relating direct and continuation semantics (Filinski's favorite -- this one is tough going)
Separation Logic: A Logic for Shared Mutable Data Structures

Also, while I'm at it, let me recommend
You and Your Research, by Richard Hamming. Want to do Nobel-class research? It's not just a matter of luck. Here is a nuts and bolts guide, from the third winner of the Turing Award.

For FractaSketch. My kids love it!

For "Logic programming in the context of multiparadigm programming: the Oz experience". I always knew Oz was interesting. But, without a lot of time to sit down and write programs, how does one come to grips with a new paradigm? This paper does the trick.

Thanks, Peter!

Hi All,

This is a quick note to say that LLVM 1.5 is out, with many new features above and beyond LLVM 1.4. Perhaps the biggest feature of interest to this community is full support for proper tail calls, as described in the release notes. More details about the release can be found in the release notes and in the two status updates [1,2] since 1.4.

For those not familiar with LLVM, it is a compiler system that can be used to build a wide variety of compiler and language systems. It provides language- and target-independent tools for building static compilers, interprocedural optimizers, JITs, etc. If you are working on a new language and need a code generator, you should check it out. LLVM can be used in two ways: 1) link to the libraries we provide for direct access to the APIs. or 2) emit the LLVM IR as a text file. People have even written (toy) languages in perl using the second technique.

-Chris

This article points out how open source scripting languages are in vogue in the corporate world:

Scripting languages have been used to build millions of applications on the Web, but in general have not been adopted widely by corporate developers. But more and more businesses and IT professionals are looking to these languages as a way to simplify and speed the creation of custom in-house programs, thus avoiding the now all-too-common logjam of late or overbudget applications.

Personally, I think the rise of these scripting languages as well as languages like Java demonstrates that the use of new programming languages is more fluid than most are willing to admit. Of course, it also demonstrates that building new scripting languages is becoming easier and easier.

(via PLNews)