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Simple haskell problem ! Help please
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Here are some hints to consider: 1. There are two ways to think about this -- pattern matching on a list, or higher-order functions 2. The former will require thinking about several cases, a. What is a "compressed" empty list? b. How many elements do we need to look at at once? c. What happens if the first and the next element are the same?... more »
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Cabal
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I made small improvements in the Small Japi Binding, and asked how to make it available. I received a few private messages advising me to build and package the library using a tool called cabal. Since I have used installation tools for PLT, R and LaTeX libraries, I thought cabal was something similar. However, I noticed that there are a lot of complaints against cabal. Therefore, I decided to install cabal, and try it. It seems that it is easier to install packages by hand than using cabal. Here is a typical cabal session:... more »
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Urgent: Please suggest me for Flow Caml Compiler
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Hello, I undertsand that this is Haskell cafe discussion forum. But I would highly appreciate if anyone can tell me where can I get Compiler and editor for FLow Caml ( it's a ML based language)) as I am not able to find it on net :(. Thanks in Adavnce! Akshay ______________________________ ______________________________ _____... more »
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bit of help with n-ary please...
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Hi, Ok what im trying to do is replace an element in an n-ary and display the completed tree. So this is what ive got so far. data Tree a = Empty |Leaf a|Branch a [Tree a] deriving (Show) replace :: Eq a=>a->a->Tree a -> (Tree a) replace x y Empty = Element x replace x y (Leaf z) | x==z = (Leaf y)... more »
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getting ready to sprint! darcs: 14-15 Nov, Portland/Vienna
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Hi everybody, We're less than one week away from the third Darcs Hacking Sprint, taking place in Portland and in Vienna on 14-15 November. Everybody is welcome (Haskell and Darcs newbies included), but please do let us know if you're thinking of attending! Preflight checklist ------------------- We've got our work cut out for us, so we want to make sure that we can hit the... more »
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call for help: FOSDEM devroom
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Hi, I'm thinking of trying to get a devroom for haskell.org at the next FOSDEM, which is Saturday-Sunday February 6th-7th 2010 in Brussels: [link] The idea would be to try to introduce Haskell to people at FOSDEM who were interested, and thus help build our ties with We'd try to have a few... more »
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Area from [(x,y)] using foldl
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Here's an (Fortran) algorithm for calculating an area, given one dimensional arrays of Xs and Ys. I wrote a recursive Haskell function that works, and one using FOLDL that doesn't. Why would Haskell be "expecting" (t, t) out of ((*) (xold-x) (yold+y))? Michael ==================== AREA = 0.0 XOLD = XVERT(NVERT)... more »
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parse String -> Expression
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Hi, I'm trying to find a way to parseRPN (Reverse Polish Numbers) to expressions rather than to just numbers. e.g. I want the answer to be in the form (Multiply (Val 2) (Val 3)) rather than just the answer. Are these anyway near the steps parseRPN :: String->Expression This is a lot more complicated then I thought.!!!... more »
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Haskell image libraries
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Haskellers, To add image support to fdo-notify, I need an image type. Looking through Hackage, I didn't find any image library with the following features: * Load from a variety of formats (at least PNG and JPG, I'd say) * Efficient per-pixel access, or a way to dump the image into a ByteString as a bitmap (I need to serialise them into the protocol's... more »
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MULTICONF-10 Call for papers
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MULTICONF-10 Call for papers The 2010 multi-conference (MULTICONF-10) (website: [link]) will be held during July 12-14, 2010 in Orlando, Florida, USA. The primary goal of MULTICONF is to promote research and developmental activities in computer science, information technology, control engineering, and related fields. Another goal is to promote the dissemination of research to a multidisciplinary audience and to facilitate communication among researchers, developers, practitioners in different fields. The following conferences are planned to be organized as part of MULTICONF-10.... more »
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