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Published on 2010-04-04T22:27:32Z
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mifun s = foldr op 0 s
where op x r = head x + r
Is there a way to make ghci tell me?
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Trying to learn Haskell. I am trying to write a simple function to remove a number from a list without using built-in function (delete...I think). For the sake of simplicity, let's assume that the input parameter is an Integer and the list is an Integer list. Here is the code I have, Please tell me…
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I'm trying to use Haskells Data.Heap module, but I'm incapable of even using it with integers. The only heap I've been capable of using is "empty", which does not take any arguments.
Later on I'll figure out how to instance for my needs, but for now I'd be glad if I was even able to test it with…
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There has been some intermingling of Scala and Haskell communities, and I have noticed now and then people commenting on stuff that's supposed to be easy in Haskell and hard and Scala. Less often (maybe because I read Scala questions, not Haskell ones), I see someone mentioning that something in Scala…
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I have problems installing ghc-mod on my linux machine. cabal worries about "happy" not being available in versione = 1.17:
$ cabal install ghc-mod
Resolving dependencies...
[1 of 1] Compiling Main ( /tmp/haskell-src-exts-1.14.0-1357/haskell-src-exts-1.14.0/Setup.hs, /tmp/haskell-src-exts-1…
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fibs :: [Int]
fibs = 0 : 1 : [ a + b | (a, b) <- zip fibs (tail fibs)]
This generates the Fibonacci sequence.
I understand the behaviour of the guards, of :, zip and tail, but I don't understand <-. What is it doing here?
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For a tool I'm writing ( http://hackage.haskell.org/package/explore ) I need a way to read haskell function definitions at run-time, apply them to values from my tool and retrieve the results of their application.
Can anyone give me a very basic example using GHC (6.10.4 or 6.12.1) API?
example…
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I recently installed GHC 6.12 and the Haskell Platform 2010.1.0.1 on my Intel MacBook running OS X 10.5.8, and initially, everything worked fine. However, I discovered that if I use cabal install to install a package which depends on a MacPorts library (e.g., cabal install --extra-lib-dirs=/opt/local/lib…
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I was just curious about some exact implementation details of lists in Haskell (GHC-specific answers are fine)--are they naive linked lists, or do they have any special optimizations? More specifically:
Do length and (!!) (for instance) have to iterate through the list?
If so, are their values…
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In relation to how packages are created, installed and used in Haskell, what are the differences between ghc-pkg and cabal? When would you use one or the other or both?
Are they complementary tools, competitive tools, or simply tools that do different jobs?
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I've installed the latest GHC package (6.12.1) on OS X, but I can't get Cabal to work. I've removed the version I had previously that worked with GHC 6.10 and tried to re-install from scratch. The latest Cabal version available for download is 1.6.0.2. However, when I try to build this I get the…
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