Registration for Haskell in Leipzig 2017 is open

Haskell in Leipzig 2017 opened its gates for everyone interested in Haskell and generally functional programming. Expect a great day of talks, tutorials, and a performance with a focus on FRP, followed by a Hackathon. Register early and get your ticket at a reduced rate. Looking forward to meeting you in Leipzig.

Haskell in Leipzig 2017 submission deadline ahead

Let me remind you that the submission deadline of Haskell in Leipzig 2017 is this Friday. We seek abstracts of about 2 pages length on anything related to Haskell. Looking forward to your contributions. 😉

Haskell in Leipzig 2017 submission deadline shifted

We have shifted the submission deadline of Haskell in Leipzig 2017 by two weeks. The new deadline is at August 18, 2017. Looking forward to your contributions. 😉

Haskell in Leipzig 2017 seeking contributions

Haskell in Leipzig (HaL) is taking place again from October 26 to October 28, 2017 at HTWK Leipzig. If you have any interesting Haskell-related material to share, please consider submitting an extended abstract.

Generic programming in Haskell

Generic programming is a powerful way to define a function that works in an analogous way for a class of types. In this article, I describe the latest approach to generic programming that is implemented in GHC. This approach goes back to the paper A Generic Deriving Mechanism for Haskell by José Pedro Magalhães, Atze Dijkstra, Johan Jeuring, and Andres Löh.

Constrained monads

There are Haskell types that have an associated monad structure, but cannot be made instances of the Monad class. The reason is typically that the return or the bind operation of such a type m has a constraint on the type parameter of m. As a result, all the nice library support for monads is unusable for such types. This problem is called the constrained-monad problem.

In my article The Constraint kind, I described a solution to this problem, which involved changing the Monad class. In this article, I present a solution that works with the standard Monad class. This solution has been developed by Neil Sculthorpe, Jan Bracker, George Giorgidze, and Andy Gill. It is described in their paper The Constrained-Monad Problem and implemented in the constrained-normal package.

MIU in Curry

More than two years ago, my colleague Denis Firsov and I gave a series of three Theory Lunch talks about the MIU string rewriting system from Douglas Hofstadter’s MU puzzle. The first talk was about a Haskell implementation of MIU, the second talk was an introduction to the functional logic programming language Curry, and the third talk was about a Curry implementation of MIU. The blog articles MIU in Haskell and A taste of Curry are write-ups of the first two talks. However, a write-up of the third talk has never seen the light of day so far. This is changed with this article.

A taste of Curry

Curry is a programming language that integrates functional and logic programming. Last week, Denis Firsov and I had a look at Curry, and Thursday, I gave an introductory talk about Curry in the Theory Lunch. This blog post is mostly a write-up of my talk.

MIU in Haskell

In the Theory Lunch of the last week, James Chapman talked about the MU puzzle from Douglas Hofstadter’s book Gödel, Escher, Bach. This puzzle is about a string rewriting system. James presented a Haskell program that computes derivations of strings. Inspired by this, I wrote my own implementation, with the goal of improving efficiency. This blog post presents this implementation. As usual, it is available as a literate Haskell file, which you can load into GHCi.

The Constraint kind

A recent language extension of the Glasgow Haskell Compiler (GHC) is the Constraint kind. In this blog post, I will show some examples of how this new feature can be used. This is a write-up of my Theory Lunch talk from 7 February 2013. The source of this article is a literate Haskell file, which you can download and load into GHCi.