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ANN: The Monad.Reader - Issue7
by Wouter Swierstra 30 Apr '07

30 Apr '07

I am pleased to announce that the latest issue of The Monad.Reader is now available: http://www.haskell.org/haskellwiki/The_Monad.Reader Issue 7 consists of the following four articles: * Matthew Naylor A Recipe for controlling Lego using Lava * Yaron Minsky Caml Trading: Experiences in Functional Programming on Wall Street * Duncan Coutts Book Review: “Programming in Haskell” by Graham Hutton * Dimitry Golubovsky, Neil Mitchell, Matthew Naylor Yhc.Core – from Haskell to Core The Monad.Reader is a quarterly magazine about functional programming. It is less-formal than journal, but somehow more enduring than a wiki page or blog post. If you'd like to submit something to the next issue of The Monad.Reader, please get in touch. I haven't fixed the deadline for the next issue just yet; I hope to send out an official call for copy in the coming weeks. Wouter This message has been checked for viruses but the contents of an attachment may still contain software viruses, which could damage your computer system: you are advised to perform your own checks. Email communications with the University of Nottingham may be monitored as permitted by UK legislation.

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COM and Haskell
by Justin Bailey 30 Apr '07

30 Apr '07

All, I'm interested in automating Excel using Haskell. I'm writing a little program for my wife and it'd be nice to fill out an Excel spreadsheet for her (with formatting so I don't think CSV will cut it). A bit of Googling didn't turn up anything interesting. Has any work been done on using Excel (or more generally, COM) from Haskell? Thanks for any pointers! Justin p.s. I'm aware of the article "Spreadsheet for Functional Programmers" article and Neil Mitchell's post about HsExcel - but those go the wrong way :(

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PartitionBy (was: Behavior groupBy)
by Hans van Thiel 29 Apr '07

29 Apr '07

Hello All, As usual, my first attempt could be better.. -- partitions a list according to an equivalence relation import Data.List (partition) partitionBy :: (a -> a -> Bool) -> [a] -> [[a]] partitionBy eq [] = [] partitionBy eq ls = x:(partitionBy eq y) where (x,y) = partition ((head ls) `eq`) ls example> partitionBy (\x y -> (last x) == (last y)) ["abc","bd","bdc","abd"] result> [["abc","bdc"],["bd","abd"]] Of course, any crits would be appreciated, but maybe this will save somebody some time.. Thanks, Hans van Thiel

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Re: [Haskell] Re: Newbie: what are the advantages of Haskell?
by Neil Mitchell 28 Apr '07

28 Apr '07

Moving to haskell-cafe@ ... > Hi Neil, a good debugger ? What is in Google Summer of Code about it ? Updating Hat, www.haskell.org/hat - see http://code.google.com/soc/haskell/about.html > I was studing about debuging techs for haskell to build a nice > debugging enviorment in HIDE or some other IDE. It's my bacharelor > final work. > > I and my teacher are thoughting about trying "observes" in a transparent way. > The user click and point to in a source local... but the observes dont > appear in the code. We will try integrate another technique from HAT > in this imaginary (still)debugging interface. You probably want to check out the GHCi debugger (in GHC head), and GuiHat [http://www-users.cs.york.ac.uk/~ndm/hat/] Thanks Neil

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IDE support
by Philipp Volgger 28 Apr '07

28 Apr '07

What IDE support is available for Haskell (Visuall Haskell, EclipseFP), anything else?

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run-time type testing in haskell?
by Eric 28 Apr '07

28 Apr '07

In imperative languages one can test the type of a variable and downcast if necessary. Here's an example in Pseudojava: T v := ... ; if (v instanceof T') T' v' := (T')v Is it possible to do something like this in Haskell? Eric.

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Parsec beginners problem
by Jim Burton 28 Apr '07

28 Apr '07

I have a couple of questions about my first use of Parsec, which is trying to read morse code symbols from a string. I have a map of symbols: import qualified Data.Map as M morsemap = M.fromList [('A', ".-") ... , ('Z', "--..")] a string to parse, like test = "...---..-....-" and a Parser to read a single morse letter: morse1 :: GenParser Char st String morseletter = try $ M.fold ((<|>) . string) (string "") morsemap which I am hoping would be equivalent to try (string ".-") <|> (string "-.") ...etc <|> string "" but I don't know what the base of the fold should be (string "" is wrong I suppose) - what is the unit of <|>? Is there a readymade combinator for this? It fails anyway: *Main> run morse1 test parse error at (line 1, column 1): unexpected "." expecting ".-" I suppose this is because the strings I'm looking for overlap but I thought the use of try..<|> would avoid this error...? Thanks, -- View this message in context: http://www.nabble.com/Parsec-beginners-problem-tf3657821.html#a10219707 Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com.

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I need help on AVL trees
by iliali16 27 Apr '07

27 Apr '07

Can someone advise me how can I build an AVL tree becouse I have difficulties with the rotations. Since if I add a node I want to be abel to check whether the tree is balanced or not if balanced ok but if not I need to do one of the 4 rotations which is a problem for me and I want to be able to give the nodes from the keyboard. What I mean is that it is possible to build the tree from scratch. Thanks to all! -- View this message in context: http://www.nabble.com/I-need-help-on-AVL-trees-tf3657386.html#a10218190 Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com.

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tiff reader or libtiff bindings
by Andreas Voellmy 27 Apr '07

27 Apr '07

Hi, Does anyone know of a haskell library to read (and write) tiff files? Or has someone written a binding to libtiff? Thanks, Andreas

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New HaskODell user groups
by dons＠cse.unsw.edu.au 27 Apr '07

27 Apr '07

I've created a new wiki page documenting all the new user groups for Haskell that are springing up! http://haskell.org/haskellwiki/User_groups If you're starting a new group, please add it here, and publicise. -- Don P.S. Some obvious user group candidates, in my opinion, would be a Portland group, a Bay Area group and something at Chalmers... ;-)

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