Factor: an extensible interactive language

A special Galois tech talk next week, with Slava Pestov talking aboutthe Factor programming language, environment, and implementation.

Logistics

• Thursday Oct 30, 2008, 10.30 - 11.30

Abstract

Factor is a programming language which has been in development for a little over 5 years. Factor is influenced by Forth, Lisp, Smalltalk. Factor takes the best ideas from Forth -- simplicity, short, succint, code, emphasis on interactive testing, and meta-programming. Factor also brings modern high-level language features such as garbage collection, object orientation and functional programming familiar to users of languages such as Lisp, Smalltalk and Python. Finally, recognizing that no programming language is an island, Factor is portable, ships with a full-featured standard library, deploys stand-alone binaries, and interoperates with C and Objective-C.In this talk, I will give the rationale for Factor's creation, present an overview of the language, and show how Factor can be used to solve real-world problems with a minimum of fuss. At the same time, I will emphasize Factor's extensible syntax, meta-programming and reflection capabilities, and show that these features, which are unheard of in the world of mainstream programming languages, make programs easier to write, more robust, and fun.

Galois has been holding weekly technical seminars for several years on topics from functional programming, formal methods, compiler and language design, to cryptography, and operating system construction, with talks by many figures from the programming language and formal methods communities.

Click to read more ...

Type Correct Changes: A Safe Approach to Version Control Implementation

Tuesday's tech talk was a special treat, with Jason Dagit dropping by to talk about using GADTs to clean up the darcs patch theory implementation. (.pdf slides).Logistics

• Tuesday, Oct 14, 2008, 10.30 - 11.30

Abstract

Darcs is based on a data model, known as Patch Theory, that sets it apart from other version control systems. The power of this data model is that it allows Darcs to manage significant complexity with a relatively straightforward user interface.We show that Generalized Algebraic Data Types (GADTs) can be used to express several fundamental invariants and properties derived from Patch Theory. This gives our compiler, GHC, a way to statically enforce our adherence to the essential rules of our data model.Finally, we examine how these techniques can improve the quality of the darcs codebase in practice.

Galois has been holding weekly technical seminars for several years on topics from functional programming, formal methods, compiler and language design, to cryptography, and operating system construction, with talks by many figures from the programming language and formal methods communities.

Click to read more ...

Tech Talk: The Future of Cabal

Duncan Coutts, from Well-Typed, gave a tech talk on Tuesday, 7th Oct, 10.30am, at Galois, about the technical direction of Cabal, Haskell package infrastructure, and the problems of managing large volumes of Haskell code. (.pdf slides).

This will be an informal talk and discussion on two topics:AbstractA language for build systemsBuild systems are easy to start but hard to get right. We'll take the view of a language designer and look at where our current tools fall down in terms of safety/correctness and expressiveness.We'll then consider some very early ideas about what a build system language should look like and what properties it should have. Currently this takes the form of a design for a build DSL embedded in Haskell.Constraint solving problems in package deploymentWe are all familiar, at least peripherally, with package systems. Every Linux distribution has a notion of packages and most have high level tools to automate the installation of packages and all their dependencies. What is not immediately obvious is that the problem of resolving a consistent set of dependencies is hard, indeed it is NP-complete. It is possible to encode 3-SAT or Sudoku as a query on a specially crafted package repository.We will look at this problem in a bit more detail and ask if the right approach might be to apply our knowledge about constraint solving rather than the current ad-hoc solvers that most real systems use. My hope is to provoke a discussion about the problem.

Click to read more ...

Bluespec SystemVerilog

Rishiyur Nikhil, CTO of Bluespec, Inc. will be giving a tech talk on Thursday, October 2nd, at 10.30am, about Bluespec SystemVerilog.Abstract

Over the past few years, several projects in major companies have been adopting BSV (Bluespec SystemVerilog) as their next-generation tool of choice for IP design, modeling (for both architecture exploration and early software development), and verification enviroments.The reason for choosing BSV is its unique combination of:

1. excellent computation model for expressing complex concurrency and communication, based on atomic transactions and atomic transactional inter-module methods
2. very high level of abstraction and parameterization (principally inspired by Haskell)
3. full synthesizability, enabling execution on FPGAs, obtaining better performance (3 to 4 orders of magnitude) and scalability than software simulation at comparable levels of detail.

In this presentation, I will provide a brief technical overview of BSV (points 1-3 above), and describe several customer projects using BSV. I will also briefly contrast BSV with other approaches to High Level Synthesis (particularly those based on C/C++/SystemC).

Click to read more ...

Nice interview with Simon Peyton-Jones in Australian Computerworld

Here's a nice interview with Simon Peyton-Jones in the Australian version of Computerworld. It's got some nice history, interesting insights (I enjoyed hearing how eye-opening Conal Elliot's Functional Reactive Animation work was), and Simon's usual wit and wisdom.

Click to read more ...