http://www-ps.informatik.uni-kiel.de/~sebf Department of Computing Science, Christian-Albrechts-University of Kiel, Germany Fri, 10 Jul 2009 09:19:54 +0000 http://backend.userland.com/rss092 en I have finished a first draft of an [overview on declarative programming][pdf]. The section on functional programming is almost identical to the version published [previously][fp] but I have added a section on logic programming features: unbound variables, non-determinism, search, and constraints. The LP section contains a surprisingly concise solution for the ... http://www-ps.informatik.uni-kiel.de/~sebf/haskell/dp-overview.html I have finished a first draft of a [brief overview on functional programming][pdf] featuring type polymorphism, higher-order functions, lazy evaluation, class-based overloading, and equational reasoning. [comments][comments] appreciated! [pdf]: /~sebf/haskell/fp-overview.pdf [comments]: http://www.reddit.com/r/haskell/comments/8xzsx/sebastian_fischer_a_brief_overview_on_functional/ http://www-ps.informatik.uni-kiel.de/~sebf/haskell/fp-overview.html I have revised [my submission][pdf] to [ATPS'09][ATPS09] -- a german workshop on programming. The most important changes are: * a simplified implementation of iterative deepening depth-first search and * an additional section with experimental results. There is also an extended [one page abstract][abstract] summarising the work. [pdf]: /~sebf/data/pub/atps09.pdf [abstract]: /~sebf/data/pub/atps09-abstract.pdf [ATPS09]: http://www-ps.informatik.uni-kiel.de/atps09/ ## Abstract Almost ... http://www-ps.informatik.uni-kiel.de/~sebf/pub/atps09.html The paper on [Purely Functional Lazy Non-deterministic Programming](http://www-ps.informatik.uni-kiel.de/~sebf/pub/icfp09.html) describes an approach to model lazy functional logic programming in Haskell via explicit sharing of monadic effects. The corresponding [project page](http://sebfisch.github.com/explicit-sharing) explains how to install and use our code. http://www-ps.informatik.uni-kiel.de/~sebf/haskell/explicit-sharing.html [This](http://www-ps.informatik.uni-kiel.de/~sebf/data/pub/icfp09.pdf) is joint work with [Oleg Kiselyov](http://okmij.org/ftp/) and [Chung-chieh Shan](http://www.cs.rutgers.edu/~ccshan/) accepted for [ICFP'09](http://www.cs.nott.ac.uk/~gmh/icfp09.html). Functional logic programming and probabilistic programming have demonstrated the broad benefits of combining laziness (non-strict evaluation with sharing of the results) with non-determinism. Yet these benefits are seldom enjoyed in functional programming, because the existing features for non-strictness, sharing, and non-determinism in functional ... http://www-ps.informatik.uni-kiel.de/~sebf/pub/icfp09.html I had an insightful [discussion on haskell-cafe](http://www.mail-archive.com/haskell-cafe@haskell.org/msg57697.html) on how to steal the implementation of monadic bind from a continuation monad transformer. I did it twice, first re-inventing the two-continuation model for depth-first search, then discovering an implementation of breadth-first search that I didn't know before. On the go, I used higher-rank infix ... http://www-ps.informatik.uni-kiel.de/~sebf/haskell/stealing-bind.html What does this chart mean?  [find out!](http://www-ps.informatik.uni-kiel.de/~sebf/haskell/speedup-search-with-parallelism.lhs.html) http://www-ps.informatik.uni-kiel.de/~sebf/haskell/par-search.html How can you write a Haskell predicate that detects (without diverging) that both of these two infinite trees are unsorted? The [fair-predicates](http://sebfisch.github.com/fair-predicates) library gives an answer. There are [comments on reddit](http://www.reddit.com/r/haskell/comments/87enw/sebastian_fischer_fair_conjunction_and_disjunction/). http://www-ps.informatik.uni-kiel.de/~sebf/projects/fair-predicates.html Today I played with SmallCheck. Interested in what happened when I tried to find a small unsatisfiable boolean formula that is not easily detected as such? Watch [my attempts](/~sebf/haskell/unsatisfiable-formula-that-needs-guessing-to-fail.lhs.html)! (strip `.html` suffix for executable Haskell file) Update ------ After realising that the crucial step to enable SmallCheck to find the formula was *not* ... http://www-ps.informatik.uni-kiel.de/~sebf/haskell/smallcheck-experience.html I just wrote a [tiny little Haskell program](http://www-ps.informatik.uni-kiel.de/~sebf/haskell/tabulated-binomial-coefficients.lhs.html) that demonstrates a small trick: how to use an infinite global constant to speed up tree-recursive functions. Remove `.html` from it's URL to download an executable Haskell file. [comments on reddit](http://www.reddit.com/r/programming/comments/7shes/sebastian_fischer_fun_with_infinite_global/) more comments ------------- My code shows how to speed up naive recursive algorithms without changing ... http://www-ps.informatik.uni-kiel.de/~sebf/haskell/infinite-constants.html