Functional

Implicit parallel functional programming

This discussion over on the Haskell Mailing List might interest those readers following the debates on concurrency issues in the discussion group...

Non-determinism in functional languages

Non-determinism in functional languages. Sondergaard and Sestoft. The Computer Journal, Volume 35, Issue 5, pp. 514-523. 1992

The introduction of a non-deterministic operator in even an very simple functional programming language gives rise to a plethora of semantic questions. These questions are not only concerned with the choice operator itself. A surprisingly large number of different parameter passing mechanisms are made possible by the introduction of bounded non-determinism. The diversity of semantic possibilities is examined systematically...
A very useful paper if you are interested in this sort of thing. Thinking of non-determinism helps calrify muddled thinking about properties such as referential transparency.

The version I found online, alas, is a set of tiff image files, one for each page...

Implementation of FPL

Simon Peyton Jones book on the Implementation of Functional Programming Languages, circa 1987, is available online.

This book is about implementing functional programming languages using lazy graph reduction, and it divides itnto three parts.



The first part describes how to translate a high-level functional language into an intermediate language, called lambda calculus, including detailed coverage of pattern-matching and type checking. The second part begins with a simple implementation of the lambda calculus, based on graph reduction, and then develops a number of refinements and alternatives, such as super-combinators, full laziness and SK combinators. Finally, the third part describes the G-machine, a sophisticated implementation of graph reduction, which provides a dramatic increase in performance...

via the Haskell mailing lists. I've seen lots of references to this work, as it was one of the seminal works in the development of the Haskell programming language. But I can't find where it was directly discussed on LtU before.

Composable memory transactions

Composable memory transactions. Tim Harris, Simon Marlow, Simon Peyton Jones, and Maurice Herlihy. Submitted to PPoPP 2005.

Writing concurrent programs is notoriously difficult, and is of increasing practical importance. A particular source of concern is that even correctly-implemented concurrency abstractions cannot be composed together to form larger abstractions. In this paper we present a new concurrency model, based on transactional memory, that offers far richer composition. All the usual benefits of transactional memory are present (e.g. freedom from deadlock), but in addition we describe new modular forms of blocking and choice that have been inaccessible in earlier work.

The work is in the context of Concurrent Haskell (of course). The authors work from the assumption that a purely functional (they use the term declarative) language is a perfect setting for transactional memory. The reason is that mutable state is rare and explicit.

Use Continuations to Develop Complex Web Applications

An introductory article from IBM developerWorks on Cocoon, continuation-based (sometimes called "modal") web applications, and such.

If you've ever developed a non-trivial Web application, you know that development complexity is increased by the fact that Web browsers allow users to follow arbitrary navigation paths through the application. No matter where the user navigates, the onus is on you, the developer, to keep track of the possible interactions and ensure that your application works correctly. While the traditional MVC approach does allow you to handle these cases, there are other options available to help resolve application complexity. Developer and frequent developerWorks contributor Abhijit Belapurkar walks you through a continuations-based alternative that could simplify your Web application development efforts.

via comp.lang.scheme

Hume Programming Language

Stumbled across the Hume Programming Language while looking for some ML info. Hadn't seen it discussed on LtU before:

Hume is a domain-specific language targeting real-time embedded systems. Hume provides a number of high level features including higher-order functions, polymorphic types, arbitrary but sized user-defined data structures, asynchronous processes, lightweight exception handling, automatic memory management and domain-specific metaprogramming features, whilst seeking to guarantee strong space/time behaviour and maintaining overall determinacy.

A bit too preliminary and research oriented for my tastes, but the main point of interest is the attempt to provide static guarantees of resource usage (time and memory). A binary version for Linux and Mac is available, but the source code is not available for other builds (written in GHC which I notice is now available for a number of target platforms since last i checked).

An Algebraic Theory of Polymorphic Temporal Media

Paul Hudak, An Algebraic Theory of Polymorphic Temporal Media

Temporal media is information that is directly consumed by a user, and that varies with time. Examples include music, digital sound files, computer animations,and video clips. In this paper we present a polymorphic data type that captures a broad range of temporal media. We study its syntactic, temporal, and semantic properties, leading to an algebraic theory of polymorphic temporal media that is valid for underlying media types that satisfy specific constraints. The key technical result is an axiomatic semantics for polymorphic temporal media that is shown to be both sound and complete.

The theoretical incarnation of Haskore.

Completeness is proved by establishing the existence of a normal form for polymorphic temporal media values.

VHS

The main purpose of this project is to provide an extension of Microsoft Visual Studio .NET development environment with support for the Haskell functional programming language, improve user experience and productivity related to implementation tasks.

Download and play, I say.

Erlang REPOS 1.0

REPOS stands for Repository of Erlang-Projects.Org Software selection. It is a collection of major ready-to-work Erlang software. REPOS is distributed as a CDROM image (ISO). You can use every software included in the REPOS environment either directly from CDROM from your hard-drive or from a USB key.

Seems like a nice distribution technique for non-mainstream languages.

The distribution includes several software packages along with erlang, among them Xmerl, Yaws and Wings 3D.

OO Programming Styles in ML

OO Programming Styles in ML, Bernard Berthomieu.

It is shown that the essential OO concepts and idioms, including inheritance and dynamic dispatch, can be encoded in this well understood framework, without requiring any operational or typing extensions of ML...

[The encodings] do not rely on subtyping and subsumption, but on an encoding of inheritance polymorphism into paramteric polymorphism.

This isn't new (it is dated March 2000), but seems interesting.

The ML module language put to good use!

Thanks Henry!

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