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Float instance of Data.Bits
by Sam Martin 12 Jul '10

12 Jul '10

Hi, Is there a particular reason Float, Double, etc do not have instances of Data.Bits in the standard libraries? I note the Haskell 2010 report doesn't include them either. In fact, I'm not actually sure how you'd implement the instance for floating point types without having some kind of compiler-specific extension, or a c-binding. Could anyone fill in my missing knowledge here? Cheers, Sam

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ANNOUNCE: fgl-5.4.2.3
by Ivan Lazar Miljenovic 12 Jul '10

12 Jul '10

I'm pleased to present the first new release of fgl [1] since Thomas Bereknyei took over maintaining it from Martin Erwig. [1] http://hackage.haskell.org/package/fgl Before people start panicking, rioting, etc., please check the version number: this is just a bug-fix release, and not the complete re-write version which we've been talking about (since we got a little sidetracked, etc.). As such, the API hasn't changed, and this should fit right in to packages already using fgl (sorry to all those people who followed my advice and put "fgl == 5.4.2.2" in the build-depends fields of their packages' .cabal files, but I didn't expect to make another 5.4.y release). The exact change that has been made is to fix a bug pointed out to me by Tristan Allwood, in that Data.Graph.Inductive.PatriciaTree didn't support multiple edges (and furthermore this wasn't specified in the documentation). This has now been rectified. As an indication of what these changes mean, see this sample call graph produced by my SourceGraph program; when using PatriciaTree from fgl-5.4.2.2 the lines were all the same thickness; now there is among other things a loop of width 32 on getExp and a line of width 7 from getExp to maybeEnt. -- Ivan Lazar Miljenovic Ivan.Miljenovic(a)gmail.com IvanMiljenovic.wordpress.com

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Equivalence of two expressions
by Grigory Sarnitskiy 12 Jul '10

12 Jul '10

I'm not very familiar with algebra and I have a question. Imagine we have ring K. We also have two expressions formed by elements from K and binary operations (+) (*) from K. Can we decide weather these two expressions are equivalent? If there is such an algorithm, where can I find something in Haskell about it? If there is no such algorithm for a ring, maybe there is for a field?

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haskell on suse?
by gladstein＠gladstein.com 12 Jul '10

12 Jul '10

I've been spoiled by package managers that download and install everything for you, and I've forgotten how RPM works. In particular, I want to install Haskell on suse, and I read that "RPMs are available from openSUSE. " I followed the link, and found a bunch of folders of folders of RPM files. What exactly should I do to install Haskell? Sorry about the newbicity of this request, but I'm totally stumped. If suse isn't a well-supported platform, I'll switch. Thanks in advance.

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ANNOUCE: graphviz-2999.10.0.0
by Ivan Lazar Miljenovic 12 Jul '10

12 Jul '10

I'm pleased to announce a new version of my graphviz [1] library that provides bindings to the Graphviz [2] suite of tools for visualising graphs. [1]: http://hackage.haskell.org/package/graphviz [2]: http://graphviz.org/ Changes in this release: * I followed my own advice and put in bounds on the version of FGL it used... * Conversion of FGL-style graphs to `DotRepr` values is now achieved using the new `GraphvizParams` configuration type. This allows us to define a single parameter that stores all the conversion functions to pass around rather than having to pass around several functions. This also allows all the non-clustered and clustered functions to be collapsed together, whereas what used to be handled by the primed functions is now achieved by using the `setDirectedness` function. There are three default `GraphvizParams` available: - `defaultParams` provides some sensible defaults (no attributes or clustering). - `nonClusteredParams` is an alias of `defaultParams` where the clustering type is explicitly set to be `()` for cases where you don't want any clustering at all (whereas `defaultParams` allows you to set your own clustering functions). - `blankParams` sets all fields to be `undefined`; this is useful for situations where you have functions that will set some values for you and there is no sensible default you can use (mainly for the clustering function). * Expansion of the `DotRepr` class: - More common functions are now defined as methods (`getID`, etc.). - The ability to get more information about the structure of the `DotRepr` graph, as well as where all the `DotNode`s are, etc. - `graphNodes` now returns `DotNode`s defined only as part of `DotEdge`s, and will also merge duplicate `DotNode`s together. - `graphNodes` and `graphEdges` also return `GlobalAttributes` that apply to them. * The `Point` type now only has one constructor: `Point Double Double`. The `Int`-only constructor was present due to historical purposes and I thought that the `Pos` value for a `DotNode` would always be a pair of `Int`s; this turns out not to be the case (and accounted for some bugs in older versions of my SourceGraph tool; it's taken me this long to remember to fix this...). * `SortV` and `PrismOverlap` now only take `Word16` values rather than `Int`s, as they're not meant to allow negative values (the choice of using `Word16` rather than `Word` was arbitrary, and because it's unlikely those values will be large enough to require the larger values available in `Word`). * `NodeCluster` has been generalised to not have to take an `LNode` for the node type; the type alias `LNodeCluster` is available if you still want this. * Several documentation typos fixed, including one spotted by Kevin Quick. * The test-suite now allows running individual tests. -- Ivan Lazar Miljenovic Ivan.Miljenovic(a)gmail.com IvanMiljenovic.wordpress.com

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ANNOUNCE: SourceGraph-0.6.1.1 and Graphalyze-0.10.0.0
by Ivan Lazar Miljenovic 12 Jul '10

12 Jul '10

I'm pleased to announce updated versions of SourceGraph [1] (my graph-theoretic static analysis tool for Haskell) and Graphalyze [2] (a library for graph-theoretic analysis of relationships in discrete data). [1]: http://hackage.haskell.org/package/SourceGraph [2]: http://hackage.haskell.org/package/Graphalyze This version of SourceGraph now (should) only consider executables listed in .cabal files as being buildable, and both packages have been updated to use the latest versions of fgl (as well as following my own advice in putting an upper bound on the version of fgl being used...), graphviz and haskell-src-exts (SourceGraph only). Please note that SourceGraph-0.6.1.0 was a version I forgot to upload (and just realised this when I wondered why it wasn't appearing on Hackage...). The big change that should be apparent with this version of SourceGraph is that thanks to the changes I just made to the newly-uploaded fgl-5.4.2.3, multiple edges are finally being handled/visualised properly; for example see the nice thick lines in http://code.haskell.org/~ivanm/Sample_SourceGraph/SourceGraph/graphs/codeCo… (which represents among other things 32 recursive calls within getExp and 7 calls from getExp to maybeEnt). I forgot to put this in the TODOs, but here are my future plans for these packages. They're rather ambitious and I have no idea when I'll get around to them, but for all intents the only work I'm going to do on them until I do these splitting up goals is bug-fixes, etc. Graphalyze ---------- Graphalyze is going to fade away: I'm going to integrate its data -> graph conversion utilities into either my new graph library I'm going to work on during AusHack or into the successor for fgl Thomas Bereknyei and are working on (whatever we'll end up calling it), the Data.Graph.Analysis.Algorithms modules into graph-algorithms and fgl-algorithms packages and the reporting stuff into its own reporting library with different backends (pandoc, blaze, etc.). SourceGraph ----------- I want to split out and formalise the whole call-graph definitions and concepts into its own library and have sub-libraries for different languages to be able to have their own code -> call-graph conversions (so it can also be used for language-c, language-python, etc.). SourceGraph itself would then be more flexible in terms of what languages it can deal with (so it might even be possible to integrate C source files in a Haskell package into the call graph!). -- Ivan Lazar Miljenovic Ivan.Miljenovic(a)gmail.com IvanMiljenovic.wordpress.com

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Multidimensional Matrices in Haskell
by Mihai Maruseac 12 Jul '10

12 Jul '10

Hi, A friend of mine wanted to do some Cellular Automata experiments in Haskell and was asking me what packages/libraries are there for multidimensional matrices. I'm interested in both immutable and mutable ones but I don't want them to be trapped inside a monad of any kind. Any hints? -- MM

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EnumMap 0.0.2 and Containers-0.3
by Max Cantor 12 Jul '10

12 Jul '10

Is there a reason that EnumMap specifically requires containers < 0.3 or just a matter of not having been tested? It seems to compile just fine (but with one warning for a deprecated call). Max

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ANNOUNCE: UMM-0.3.0
by Uwe Hollerbach 12 Jul '10

12 Jul '10

Hi, all, I've just uploaded version 0.3.0 of umm, my small money-manager program, to hackage. This version does nicer plotting of data than before (depends on gnuplot). Have a look if you... errr... like money :-) regards, Uwe

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HaskellWiki spam
by Henk-Jan van Tuyl 11 Jul '10

11 Jul '10

L.S., There are hundreds of HaskellWiki users created, their names all start with "Buy" and their user pages contain spam. I suppose the antispam measures were reverted when a backup of the site was loaded. (B.T.W. the site still displays the old logo.) Regards, Henk-Jan van Tuyl -- http://Van.Tuyl.eu/ http://members.chello.nl/hjgtuyl/tourdemonad.html --

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