- Beginners - Haskell.org

Simplifying a 'split' function
by Ben Sanders 30 Apr '09

30 Apr '09

In looking through a merge sort implementation example, I came across this code: split :: [a] -> [[a]] split [] = [] split (x:xs) = [x] : split xs I would have written the same code as split :: [a] -> [[a]] split = map (: []) Is there any particular difference here (other than explicit recursion)? And is there any other nicer way to write it? Thanks, Ben Sanders

4 5

List Function
by Nathan Holden 30 Apr '09

30 Apr '09

I don't know what you'd call it. Is there a function in any of the basic functions that does this something like this: Sending two lists, [1,2,3] and [2,3,4] it would return [(1,4),(1,5),(1,6),(2,4),(2,5),(2,6),(3,4),(3,5),(3,6)]. I managed to code my way into returning a list of lists, which works. But it seemed like a very basic list/matrix function, so I honestly believe that the Haskell designers probably would've put it in.

8 10

Parsec tutorial
by Patrick LeBoutillier 30 Apr '09

30 Apr '09

Hi all, I'm looking for a Parsec tutorial that can get me started in writing a simple SQL parser. I can't seem to find a lot using Google. Does anyone have some resources that could be helpful? Thanks a lot, Patrick -- ===================== Patrick LeBoutillier Rosemère, Québec, Canada

3 2

P.S. "Haskell: Craft of Functional Programming"
by Michael P Mossey 29 Apr '09

29 Apr '09

Oh, and I got HCFP at the local Border's. Apparently it's selling well enough to include it in a general bookstore. Look out Stephen King---Simon Thompson is coming!

1 0

putting in a good word for "Haskell: The Craft of Functional Programming"
by Michael P Mossey 29 Apr '09

29 Apr '09

I'm working through "Haskell: the Craft of Functional Programming" (by Simon Thompson) in depth, and I want to put in a good word for it. His exercises are numerous and they seem to lead me from simpler ideas to more complex ideas in a natural way. As part of learning Haskell, I actually started with other books and tutorials and skipped around in them, reading some of the later chapters before the earlier ones. I like that sometimes. But I'm finding that Thompson's book is helpful for getting an intuition for the language, as opposed to just reading about its features, so I'm working it in order. My other books include "Real World Haskell" and "School of Expression." The wonderful thing about RWH is that it's available online (I do own a hardcopy) where people comment on the text and exercises. -Mike

1 0

International Summer School on Advances in Programming Languages
by voigt＠tcs.inf.tu-dresden.de 29 Apr '09

29 Apr '09

International Summer School on Advances in Programming Languages 25th-28th August, 2009 Heriot-Watt University, Edinburgh, Scotland http://www.macs.hw.ac.uk/~greg/ISS-AiPL Overview This four-day residential International Summer School on Advances in Programming Languages has a major theme of Concurrency, Distribution, and Multicore. Intended primarily for postgraduate research students, the School offers lectures and practical sessions on an engaging blend of cutting edge theoretical and practical techniques from international experts. The Summer School is supported by the Scottish Informatics and Computer Science Alliance (http://www.sicsa.ac.uk/) a Scottish Funding Council Research Pool. Participants from SICSA member institutions may attend at no cost. Confirmed Topics/Speakers - Static and dynamic languages, Prof Phillip Wadler, University of Edinburgh - Compiler technology for data-parallel languages, Dr Sven-Bodo Scholz, University of Hertfordshire - New applications of parametricity, Dr Janis Voigtlaender, Technical University of Dresden - Automatic vectorising compilation, Dr Paul Cockshott, University of Glasgow - Foundational aspects of size analysis, Prof Marko van Eekelen/Dr Olha Shakaravska, Radboud University Nijmegen - Context oriented programming, Dr Pascal Costanza, Vrije Universiteit Brussel - Multi-core programming, Dr Phil Trinder, Heriot-Watt University - Multi-core compilation, Dr Alastair Donaldson, Codeplay Software Ltd - Principles and Applications of Refinement Types, Dr Andrew D. Gordon, Microsoft Research, Cambridge - Resource aware programming in Hume, Prof Greg Michaelson, Heriot-Watt University/ Prof Kevin Hammond, University of St Andrews - Haskell concurrency & parallelism, Dr Satnam Singh, Microsoft Research, Cambridge Location The Summer School is based at Heriot-Watt University's Riccarton campus, set in pleasant parkland to the west of Edinburgh, with easy access to the airport, city and central Scotland: http://www.hw.ac.uk/welcome/directions.htm. The Summer School immediately precedes the 2009 International Conference on Functional Programming (http://www.cs.nott.ac.uk/~gmh/icfp09.html) and takes place during the Edinburgh International Festival (http://www.eif.co.uk/) and the associated Edinburgh Festival Fringe (http://www.edfringe.com/) and Edinburgh International Book Festival (http://www.edbookfest.co.uk/) Steering Committee Prof Greg Michaelson, Heriot-Watt University (Convenor) (mailto:G.Michaelson@hw.ac.uk) Prof Kevin Hammond, University of St Andrews Dr Patricia Johann, University of Strathclyde Prof Phillip Wadler, University of Edinburgh

1 0

Need Help
by kaushal Pathak 29 Apr '09

29 Apr '09

Hi There, Here is a very simple haskell program I have written to find whether a number is prime or not, which doesn't give me any compilation error but gives following run-time error : Any help would help me move ahead, I know that the type concepts is what I am lacking, anly pointer to simple/good article/paper would definitely help. Lots of thannx jut even to look at the mail :-) Regards Kaushal *Run Time Error :* kaushal > isPrime1 171 <interactive>:1:0: Ambiguous type variable `t' in the constraints: `Integral t' arising from a use of `isPrime1' at <interactive>:1:0-11 `Floating t' arising from a use of `isPrime1' at <interactive>:1:0-11 `RealFrac t' arising from a use of `isPrime1' at <interactive>:1:0-11 Probable fix: add a type signature that fixes these type variable(s) kaushal > *Program :* isPrime1 x = let canDivide num 0 = 0 canDivide num 1 = 0 canDivide num divisor = if ((mod num divisor) == 0) then 1 else canDivide num (divisor - 1) in if ( x == 1 ) then putStrLn("1 is Neither prime nor composite!!!") else if ((canDivide x first_div) == 1) then putStrLn(show(x) ++ " is not a Prime Number!!!") else putStrLn(show(x) ++ " is a Prime Number!!!") where first_div :: Integral a => a ; first_div = round (sqrt x)

4 5

Working With TVars
by aditya siram 28 Apr '09

28 Apr '09

Hi all, I have a tuple inside a TVar : > type MySTM = TVar (Int,Int) Whenever I want to edit/read 'a' or 'b' I find myself writing : > editFunction mySTM = do (a',b') <- readTVar mySTM dostuff a' ... This is boilerplate stuff, so I decided to write some accessors. So far I have : > getA , getB :: MySTM -> STM Int > getA mySTM = do > (a',b') <- readTVar mySTM > return a' > > getB mySTM = do > (a',b') <- readTVar mySTM > return b' I want to be able to use these accessors like so: > doSomethingWithA mySTM = do > case (getA mySTM) of > 1 -> doStuff > 0 -> doSomethingElse But getA returns an STM Int, so I still have to do a : > doSomethingWithA = do > a' <- (getA mySTM) > case a' of > 1 -> doStuff > 0 -> doSomethingElse This doesn't really save me a lot of boilerplate. What is the best way of writing a function that just returns my values do I can work with them in the STM monad without unpacking them all the time? Thanks , Deech

3 2

Problem install ghc 6.10.2
by aditya siram 28 Apr '09

28 Apr '09

Hi all, I am trying to install the Linux GHC 6.10.2 binary, but when I fire up ghci I get the following error: GHCi, version 6.10.2: http://www.haskell.org/ghc/ :? for help Glasgow Haskell Compiler, Version 6.10.2, for Haskell 98, stage 2 booted by GHC version 6.10.1 Using package config file: /usr/local/lib/ghc-6.10.2/./package.conf wired-in package ghc-prim[""] not found. wired-in package integer[""] not found. wired-in package base[""] not found. wired-in package rts mapped to rts-1.0 wired-in package haskell98[""] not found. wired-in package syb[""] not found. wired-in package template-haskell[""] not found. wired-in package dph-seq[""] not found. wired-in package dph-par[""] not found. package haddock-2.4.2 will be ignored due to missing or recursive dependencies: Cabal-1.6.0.3 array-0.2.0.0 base-4.1.0.0 containers-0.2.0.1 directory-1.0.0.3 filepath-1.1.0.2 ghc-6.10.2 haskell98-1.0.1.0 pretty-1.0.1.0 package ghc-6.10.2 will be ignored due to missing or recursive dependencies: Cabal-1.6.0.3 array-0.2.0.0 base-4.1.0.0 bytestring-0.9.1.4 containers-0.2.0.1 directory-1.0.0.3 editline-0.2.1.0 filepath-1.1.0.2 haskell98-1.0.1.0 hpc-0.5.0.3 old-time-1.0.0.2 process-1.0.1.1 template-haskell-2.3.0.1 unix-2.3.2.0 Hsc static flags: -static *** Deleting temp files: Deleting: *** Deleting temp dirs: Deleting: ghc: panic! (the 'impossible' happened) (GHC version 6.10.2 for i386-unknown-linux): interactiveUI:setBuffering2 Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug Running ghc-pkg check gave me : There are problems in package haddock-2.4.2: dependency Cabal-1.6.0.3 doesn't exist dependency array-0.2.0.0 doesn't exist dependency base-4.1.0.0 doesn't exist dependency containers-0.2.0.1 doesn't exist dependency directory-1.0.0.3 doesn't exist dependency filepath-1.1.0.2 doesn't exist dependency haskell98-1.0.1.0 doesn't exist dependency pretty-1.0.1.0 doesn't exist There are problems in package ghc-6.10.2: dependency Cabal-1.6.0.3 doesn't exist dependency array-0.2.0.0 doesn't exist dependency base-4.1.0.0 doesn't exist dependency bytestring-0.9.1.4 doesn't exist dependency containers-0.2.0.1 doesn't exist dependency directory-1.0.0.3 doesn't exist dependency editline-0.2.1.0 doesn't exist dependency filepath-1.1.0.2 doesn't exist dependency haskell98-1.0.1.0 doesn't exist dependency hpc-0.5.0.3 doesn't exist dependency old-time-1.0.0.2 doesn't exist dependency process-1.0.1.1 doesn't exist dependency template-haskell-2.3.0.1 doesn't exist dependency unix-2.3.2.0 doesn't exist The following packages are broken, either because they have a problem listed above, or because they depend on a broken package. haddock-2.4.2 ghc-6.10.2 Listing user packages ( ghc-pkg list --user ) shows that ghc-pkg is looking for a package.conf in ~/.ghc/i386-linux-6.10.2/package.conf which doesn't exist:. So I created it and copied over the package.conf file from ~/.ghc/i386-linux-6.10.1/ and ran ghc-pkg check again with the following error : There are problems in package CC-delcont-0.2: dependency base-3.0.3.0 doesn't exist dependency mtl-1.1.0.2 doesn't exist There are problems in package terminfo-0.2.2.1: dependency base-3.0.3.0 doesn't exist There are problems in package darcs-2.2.0: dependency array-0.2.0.0 doesn't exist dependency base-3.0.3.0 doesn't exist dependency bytestring-0.9.1.4 doesn't exist dependency containers-0.2.0.0 doesn't exist dependency directory-1.0.0.2 doesn't exist dependency filepath-1.1.0.1 doesn't exist dependency html-1.0.1.2 doesn't exist dependency mtl-1.1.0.2 doesn't exist dependency old-time-1.0.0.1 doesn't exist dependency parsec-2.1.0.1 doesn't exist dependency process-1.0.1.0 doesn't exist dependency random-1.0.0.1 doesn't exist dependency regex-compat-0.71.0.1 doesn't exist dependency unix-2.3.1.0 doesn't exist There are problems in package extensible-exceptions-0.1.1.0: dependency base-4.0.0.0 doesn't exist There are problems in package binary-0.4.4: dependency array-0.2.0.0 doesn't exist dependency base-3.0.3.0 doesn't exist dependency bytestring-0.9.1.4 doesn't exist dependency containers-0.2.0.0 doesn't exist There are problems in package syb-with-class-0.4: dependency array-0.2.0.0 doesn't exist dependency base-3.0.3.0 doesn't exist dependency bytestring-0.9.1.4 doesn't exist dependency template-haskell-2.3.0.0 doesn't exist There are problems in package hspread-0.3.1: dependency base-3.0.3.0 doesn't exist dependency bytestring-0.9.1.4 doesn't exist dependency containers-0.2.0.0 doesn't exist There are problems in package happstack-state-0.1: dependency base-4.0.0.0 doesn't exist dependency bytestring-0.9.1.4 doesn't exist dependency containers-0.2.0.0 doesn't exist dependency directory-1.0.0.2 doesn't exist dependency filepath-1.1.0.1 doesn't exist dependency mtl-1.1.0.2 doesn't exist dependency old-time-1.0.0.1 doesn't exist dependency random-1.0.0.1 doesn't exist dependency stm-2.1.1.2 doesn't exist dependency syb-0.1.0.0 doesn't exist dependency template-haskell-2.3.0.0 doesn't exist dependency unix-2.3.1.0 doesn't exist There are problems in package happstack-ixset-0.1: dependency base-4.0.0.0 doesn't exist dependency containers-0.2.0.0 doesn't exist dependency mtl-1.1.0.2 doesn't exist dependency syb-0.1.0.0 doesn't exist dependency template-haskell-2.3.0.0 doesn't exist There are problems in package happstack-server-0.1: dependency base-4.0.0.0 doesn't exist dependency bytestring-0.9.1.4 doesn't exist dependency containers-0.2.0.0 doesn't exist dependency directory-1.0.0.2 doesn't exist dependency html-1.0.1.2 doesn't exist dependency mtl-1.1.0.2 doesn't exist dependency old-locale-1.0.0.1 doesn't exist dependency old-time-1.0.0.1 doesn't exist dependency parsec-2.1.0.1 doesn't exist dependency process-1.0.1.0 doesn't exist dependency syb-0.1.0.0 doesn't exist dependency template-haskell-2.3.0.0 doesn't exist dependency unix-2.3.1.0 doesn't exist dependency xhtml-3000.2.0.1 doesn't exist There are problems in package happstack-contrib-0.1: dependency base-4.0.0.0 doesn't exist dependency bytestring-0.9.1.4 doesn't exist dependency directory-1.0.0.2 doesn't exist dependency mtl-1.1.0.2 doesn't exist dependency old-time-1.0.0.1 doesn't exist dependency syb-0.1.0.0 doesn't exist dependency unix-2.3.1.0 doesn't exist There are problems in package X11-1.4.5: dependency base-3.0.3.0 doesn't exist There are problems in package xmonad-0.8.1: dependency base-3.0.3.0 doesn't exist dependency containers-0.2.0.0 doesn't exist dependency directory-1.0.0.2 doesn't exist dependency mtl-1.1.0.2 doesn't exist dependency process-1.0.1.0 doesn't exist dependency unix-2.3.1.0 doesn't exist There are problems in package utf8-string-0.3.4: dependency base-3.0.3.0 doesn't exist dependency bytestring-0.9.1.4 doesn't exist There are problems in package X11-xft-0.3: dependency base-3.0.3.0 doesn't exist There are problems in package ghc-paths-0.1.0.5: dependency base-3.0.3.0 doesn't exist There are problems in package haddock-2.4.1: dependency Cabal-1.6.0.1 doesn't exist dependency array-0.2.0.0 doesn't exist dependency base-4.0.0.0 doesn't exist dependency containers-0.2.0.0 doesn't exist dependency directory-1.0.0.2 doesn't exist dependency filepath-1.1.0.1 doesn't exist dependency ghc-6.10.1 doesn't exist dependency pretty-1.0.1.0 doesn't exist There are problems in package regex-base-0.93.1: dependency array-0.2.0.0 doesn't exist dependency base-3.0.3.0 doesn't exist dependency bytestring-0.9.1.4 doesn't exist dependency containers-0.2.0.0 doesn't exist dependency mtl-1.1.0.2 doesn't exist There are problems in package regex-posix-0.94.1: dependency array-0.2.0.0 doesn't exist dependency base-3.0.3.0 doesn't exist dependency bytestring-0.9.1.4 doesn't exist dependency containers-0.2.0.0 doesn't exist There are problems in package regex-compat-0.92: dependency array-0.2.0.0 doesn't exist dependency base-3.0.3.0 doesn't exist There are problems in package syb-with-class-0.5.1: dependency array-0.2.0.0 doesn't exist dependency base-3.0.3.0 doesn't exist dependency bytestring-0.9.1.4 doesn't exist dependency containers-0.2.0.0 doesn't exist dependency template-haskell-2.3.0.0 doesn't exist There are problems in package terminfo-0.3: dependency base-3.0.3.0 doesn't exist There are problems in package time-1.1.2.3: dependency base-3.0.3.0 doesn't exist dependency old-locale-1.0.0.1 doesn't exist There are problems in package xmonad-contrib-0.8.1: dependency base-3.0.3.0 doesn't exist dependency containers-0.2.0.0 doesn't exist dependency directory-1.0.0.2 doesn't exist dependency mtl-1.1.0.2 doesn't exist dependency old-locale-1.0.0.1 doesn't exist dependency old-time-1.0.0.1 doesn't exist dependency process-1.0.1.0 doesn't exist dependency random-1.0.0.1 doesn't exist dependency unix-2.3.1.0 doesn't exist There are problems in package wxcore-0.11.0: dependency base-4.0.0.0 doesn't exist dependency containers-0.2.0.0 doesn't exist dependency bytestring-0.9.1.4 doesn't exist dependency stm-2.1.1.2 doesn't exist There are problems in package process-1.0.1.1: dependency base-4.0.0.0 doesn't exist dependency directory-1.0.0.2 doesn't exist dependency filepath-1.1.0.1 doesn't exist dependency unix-2.3.1.0 doesn't exist There are problems in package darcs-2.2.1: dependency array-0.2.0.0 doesn't exist dependency base-3.0.3.0 doesn't exist dependency bytestring-0.9.1.4 doesn't exist dependency containers-0.2.0.0 doesn't exist dependency directory-1.0.0.2 doesn't exist dependency filepath-1.1.0.1 doesn't exist dependency html-1.0.1.2 doesn't exist dependency mtl-1.1.0.2 doesn't exist dependency old-time-1.0.0.1 doesn't exist dependency parsec-2.1.0.1 doesn't exist dependency random-1.0.0.1 doesn't exist dependency unix-2.3.1.0 doesn't exist There are problems in package haskell98-1.0.1.0: dependency array-0.2.0.0 doesn't exist dependency base-4.0.0.0 doesn't exist dependency directory-1.0.0.2 doesn't exist dependency old-locale-1.0.0.1 doesn't exist dependency old-time-1.0.0.1 doesn't exist dependency random-1.0.0.1 doesn't exist There are problems in package HaXml-1.13.3: dependency base-3.0.3.0 doesn't exist dependency containers-0.2.0.0 doesn't exist dependency pretty-1.0.1.0 doesn't exist There are problems in package terminfo-0.3.0.1: dependency base-3.0.3.0 doesn't exist There are problems in package hslogger-1.0.7: dependency base-3.0.3.0 doesn't exist dependency containers-0.2.0.0 doesn't exist dependency directory-1.0.0.2 doesn't exist dependency mtl-1.1.0.2 doesn't exist dependency old-locale-1.0.0.1 doesn't exist dependency unix-2.3.1.0 doesn't exist There are problems in package happstack-util-0.1: dependency HUnit-1.2.0.3 doesn't exist dependency QuickCheck-1.2.0.0 doesn't exist dependency array-0.2.0.0 doesn't exist dependency base-4.0.0.0 doesn't exist dependency bytestring-0.9.1.4 doesn't exist dependency directory-1.0.0.2 doesn't exist dependency mtl-1.1.0.2 doesn't exist dependency old-time-1.0.0.1 doesn't exist dependency random-1.0.0.1 doesn't exist dependency template-haskell-2.3.0.0 doesn't exist There are problems in package happstack-data-0.1: dependency base-4.0.0.0 doesn't exist dependency bytestring-0.9.1.4 doesn't exist dependency containers-0.2.0.0 doesn't exist dependency mtl-1.1.0.2 doesn't exist dependency pretty-1.0.1.0 doesn't exist dependency syb-0.1.0.0 doesn't exist dependency template-haskell-2.3.0.0 doesn't exist There are problems in package happstack-util-0.1.9: dependency HUnit-1.2.0.3 doesn't exist dependency QuickCheck-1.2.0.0 doesn't exist dependency array-0.2.0.0 doesn't exist dependency base-4.0.0.0 doesn't exist dependency bytestring-0.9.1.4 doesn't exist dependency directory-1.0.0.2 doesn't exist dependency mtl-1.1.0.2 doesn't exist dependency old-time-1.0.0.1 doesn't exist dependency random-1.0.0.1 doesn't exist dependency template-haskell-2.3.0.0 doesn't exist There are problems in package happstack-data-0.1.9: dependency HUnit-1.2.0.3 doesn't exist dependency base-4.0.0.0 doesn't exist dependency bytestring-0.9.1.4 doesn't exist dependency containers-0.2.0.0 doesn't exist dependency mtl-1.1.0.2 doesn't exist dependency pretty-1.0.1.0 doesn't exist dependency syb-0.1.0.0 doesn't exist dependency template-haskell-2.3.0.0 doesn't exist There are problems in package happstack-state-0.1.9: dependency HUnit-1.2.0.3 doesn't exist dependency base-4.0.0.0 doesn't exist dependency bytestring-0.9.1.4 doesn't exist dependency containers-0.2.0.0 doesn't exist dependency directory-1.0.0.2 doesn't exist dependency filepath-1.1.0.1 doesn't exist dependency mtl-1.1.0.2 doesn't exist dependency old-time-1.0.0.1 doesn't exist dependency random-1.0.0.1 doesn't exist dependency stm-2.1.1.2 doesn't exist dependency syb-0.1.0.0 doesn't exist dependency template-haskell-2.3.0.0 doesn't exist dependency unix-2.3.1.0 doesn't exist There are problems in package happstack-ixset-0.1.9: dependency HUnit-1.2.0.3 doesn't exist dependency base-4.0.0.0 doesn't exist dependency containers-0.2.0.0 doesn't exist dependency mtl-1.1.0.2 doesn't exist dependency syb-0.1.0.0 doesn't exist dependency template-haskell-2.3.0.0 doesn't exist There are problems in package MaybeT-0.1.2: dependency base-3.0.3.0 doesn't exist dependency mtl-1.1.0.2 doesn't exist There are problems in package zlib-0.5.0.0: dependency base-3.0.3.0 doesn't exist dependency bytestring-0.9.1.4 doesn't exist There are problems in package happstack-server-0.1.9: dependency HUnit-1.2.0.3 doesn't exist dependency base-4.0.0.0 doesn't exist dependency bytestring-0.9.1.4 doesn't exist dependency containers-0.2.0.0 doesn't exist dependency directory-1.0.0.2 doesn't exist dependency html-1.0.1.2 doesn't exist dependency mtl-1.1.0.2 doesn't exist dependency old-locale-1.0.0.1 doesn't exist dependency old-time-1.0.0.1 doesn't exist dependency parsec-2.1.0.1 doesn't exist dependency syb-0.1.0.0 doesn't exist dependency template-haskell-2.3.0.0 doesn't exist dependency unix-2.3.1.0 doesn't exist dependency xhtml-3000.2.0.1 doesn't exist There are problems in package happstack-contrib-0.1.9: dependency HUnit-1.2.0.3 doesn't exist dependency base-4.0.0.0 doesn't exist dependency bytestring-0.9.1.4 doesn't exist dependency directory-1.0.0.2 doesn't exist dependency mtl-1.1.0.2 doesn't exist dependency old-time-1.0.0.1 doesn't exist dependency syb-0.1.0.0 doesn't exist dependency unix-2.3.1.0 doesn't exist There are problems in package HJavaScript-0.4.4: dependency base-3.0.3.0 doesn't exist There are problems in package cpphs-1.6: dependency base-3.0.3.0 doesn't exist There are problems in package harp-0.4: dependency base-3.0.3.0 doesn't exist There are problems in package haskell-src-exts-0.4.8: dependency array-0.2.0.0 doesn't exist dependency base-4.0.0.0 doesn't exist dependency pretty-1.0.1.0 doesn't exist There are problems in package hsx-0.4.8: dependency base-3.0.3.0 doesn't exist dependency mtl-1.1.0.2 doesn't exist There are problems in package HJScript-0.4.4: dependency base-3.0.3.0 doesn't exist dependency mtl-1.1.0.2 doesn't exist There are problems in package hsp-0.4.5: dependency base-3.0.3.0 doesn't exist dependency mtl-1.1.0.2 doesn't exist There are problems in package happstack-0.1.9: dependency base-4.0.0.0 doesn't exist dependency bytestring-0.9.1.4 doesn't exist dependency directory-1.0.0.2 doesn't exist dependency filepath-1.1.0.1 doesn't exist dependency mtl-1.1.0.2 doesn't exist dependency old-time-1.0.0.1 doesn't exist dependency syb-0.1.0.0 doesn't exist There are problems in package Xauth-0.1: dependency base-3.0.3.0 doesn't exist There are problems in package byteorder-1.0.0: dependency base-3.0.3.0 doesn't exist There are problems in package xhb-0.2.2009.2.21: dependency base-3.0.3.0 doesn't exist dependency bytestring-0.9.1.4 doesn't exist dependency containers-0.2.0.0 doesn't exist dependency parsec-2.1.0.1 doesn't exist dependency stm-2.1.1.2 doesn't exist There are problems in package HStringTemplate-0.4.3: dependency array-0.2.0.0 doesn't exist dependency base-3.0.3.0 doesn't exist dependency bytestring-0.9.1.4 doesn't exist dependency containers-0.2.0.0 doesn't exist dependency directory-1.0.0.2 doesn't exist dependency filepath-1.1.0.1 doesn't exist dependency old-locale-1.0.0.1 doesn't exist dependency old-time-1.0.0.1 doesn't exist dependency parsec-2.1.0.1 doesn't exist dependency pretty-1.0.1.0 doesn't exist There are problems in package happstack-util-0.2.1: dependency HUnit-1.2.0.3 doesn't exist dependency QuickCheck-1.2.0.0 doesn't exist dependency array-0.2.0.0 doesn't exist dependency base-4.0.0.0 doesn't exist dependency bytestring-0.9.1.4 doesn't exist dependency directory-1.0.0.2 doesn't exist dependency mtl-1.1.0.2 doesn't exist dependency old-locale-1.0.0.1 doesn't exist dependency old-time-1.0.0.1 doesn't exist dependency parsec-2.1.0.1 doesn't exist dependency random-1.0.0.1 doesn't exist dependency template-haskell-2.3.0.0 doesn't exist There are problems in package happstack-data-0.2.1: dependency HUnit-1.2.0.3 doesn't exist dependency base-4.0.0.0 doesn't exist dependency bytestring-0.9.1.4 doesn't exist dependency containers-0.2.0.0 doesn't exist dependency mtl-1.1.0.2 doesn't exist dependency pretty-1.0.1.0 doesn't exist dependency syb-0.1.0.0 doesn't exist dependency template-haskell-2.3.0.0 doesn't exist There are problems in package happstack-ixset-0.2.1: dependency HUnit-1.2.0.3 doesn't exist dependency base-4.0.0.0 doesn't exist dependency containers-0.2.0.0 doesn't exist dependency mtl-1.1.0.2 doesn't exist dependency syb-0.1.0.0 doesn't exist dependency template-haskell-2.3.0.0 doesn't exist There are problems in package happstack-server-0.2.1: dependency HUnit-1.2.0.3 doesn't exist dependency base-4.0.0.0 doesn't exist dependency bytestring-0.9.1.4 doesn't exist dependency containers-0.2.0.0 doesn't exist dependency directory-1.0.0.2 doesn't exist dependency html-1.0.1.2 doesn't exist dependency mtl-1.1.0.2 doesn't exist dependency old-locale-1.0.0.1 doesn't exist dependency old-time-1.0.0.1 doesn't exist dependency parsec-2.1.0.1 doesn't exist dependency syb-0.1.0.0 doesn't exist dependency template-haskell-2.3.0.0 doesn't exist dependency unix-2.3.1.0 doesn't exist dependency xhtml-3000.2.0.1 doesn't exist There are problems in package happstack-state-0.2.1: dependency HUnit-1.2.0.3 doesn't exist dependency base-4.0.0.0 doesn't exist dependency bytestring-0.9.1.4 doesn't exist dependency containers-0.2.0.0 doesn't exist dependency directory-1.0.0.2 doesn't exist dependency filepath-1.1.0.1 doesn't exist dependency mtl-1.1.0.2 doesn't exist dependency old-time-1.0.0.1 doesn't exist dependency random-1.0.0.1 doesn't exist dependency stm-2.1.1.2 doesn't exist dependency syb-0.1.0.0 doesn't exist dependency template-haskell-2.3.0.0 doesn't exist dependency unix-2.3.1.0 doesn't exist There are problems in package happstack-0.2.1: dependency HUnit-1.2.0.3 doesn't exist dependency base-4.0.0.0 doesn't exist dependency bytestring-0.9.1.4 doesn't exist dependency directory-1.0.0.2 doesn't exist dependency filepath-1.1.0.1 doesn't exist dependency mtl-1.1.0.2 doesn't exist dependency old-time-1.0.0.1 doesn't exist dependency syb-0.1.0.0 doesn't exist There are problems in package uniplate-1.2.0.3: dependency base-4.0.0.0 doesn't exist dependency containers-0.2.0.0 doesn't exist dependency mtl-1.1.0.2 doesn't exist dependency syb-0.1.0.0 doesn't exist There are problems in package wx-0.11.0: dependency base-4.0.0.0 doesn't exist dependency stm-2.1.1.2 doesn't exist There are problems in package wx-0.11.1.2: dependency base-4.0.0.0 doesn't exist dependency stm-2.1.1.2 doesn't exist dependency wxcore-0.11.1.2 doesn't exist There are problems in package bimap-0.2.4: dependency base-3.0.3.0 doesn't exist dependency containers-0.2.0.0 doesn't exist There are problems in package encoding-0.5.1: dependency array-0.2.0.0 doesn't exist dependency base-3.0.3.0 doesn't exist dependency bytestring-0.9.1.4 doesn't exist dependency containers-0.2.0.0 doesn't exist dependency mtl-1.1.0.2 doesn't exist dependency template-haskell-2.3.0.0 doesn't exist There are problems in package fclabels-0.1: dependency base-3.0.3.0 doesn't exist dependency mtl-1.1.0.2 doesn't exist dependency template-haskell-2.3.0.0 doesn't exist There are problems in package hscolour-1.11: dependency base-3.0.3.0 doesn't exist There are problems in package parsec-3.0.0: dependency base-3.0.3.0 doesn't exist dependency bytestring-0.9.1.4 doesn't exist dependency mtl-1.1.0.2 doesn't exist There are problems in package pureMD5-0.2.4: dependency base-3.0.3.0 doesn't exist dependency bytestring-0.9.1.4 doesn't exist There are problems in package salvia-0.1.1: dependency base-3.0.3.0 doesn't exist dependency bytestring-0.9.1.4 doesn't exist dependency containers-0.2.0.0 doesn't exist dependency directory-1.0.0.2 doesn't exist dependency filepath-1.1.0.1 doesn't exist dependency mtl-1.1.0.2 doesn't exist dependency old-locale-1.0.0.1 doesn't exist dependency random-1.0.0.1 doesn't exist dependency stm-2.1.1.2 doesn't exist There are problems in package salvia-extras-0.1.1: dependency base-3.0.3.0 doesn't exist There are problems in package Diff-0.1.2: dependency array-0.2.0.0 doesn't exist dependency base-3.0.3.0 doesn't exist There are problems in package clevercss-0.1.1: dependency base-3.0.3.0 doesn't exist dependency containers-0.2.0.0 doesn't exist dependency mtl-1.1.0.2 doesn't exist dependency parsec-2.1.0.1 doesn't exist There are problems in package datetime-0.1: dependency QuickCheck-1.2.0.0 doesn't exist dependency base-3.0.3.0 doesn't exist dependency old-locale-1.0.0.1 doesn't exist dependency old-time-1.0.0.1 doesn't exist There are problems in package nano-md5-0.1.2: dependency base-3.0.3.0 doesn't exist dependency bytestring-0.9.1.4 doesn't exist There are problems in package network-2.2.0.1: dependency base-4.0.0.0 doesn't exist dependency parsec-2.1.0.1 doesn't exist There are problems in package split-0.1.1: dependency base-3.0.3.0 doesn't exist There are problems in package xml-1.3.4: dependency base-3.0.3.0 doesn't exist There are problems in package filestore-0.2: dependency base-4.0.0.0 doesn't exist dependency bytestring-0.9.1.4 doesn't exist dependency directory-1.0.0.2 doesn't exist dependency filepath-1.1.0.1 doesn't exist dependency parsec-2.1.0.1 doesn't exist There are problems in package hsemail-1.3: dependency base-3.0.3.0 doesn't exist dependency mtl-1.1.0.2 doesn't exist dependency old-time-1.0.0.1 doesn't exist dependency parsec-2.1.0.1 doesn't exist There are problems in package SMTPClient-1.0.1: dependency base-3.0.3.0 doesn't exist dependency containers-0.2.0.0 doesn't exist dependency old-locale-1.0.0.1 doesn't exist dependency old-time-1.0.0.1 doesn't exist There are problems in package HTTP-4000.0.4: dependency array-0.2.0.0 doesn't exist dependency base-3.0.3.0 doesn't exist dependency bytestring-0.9.1.4 doesn't exist dependency mtl-1.1.0.2 doesn't exist dependency old-time-1.0.0.1 doesn't exist dependency parsec-2.1.0.1 doesn't exist There are problems in package happstack-util-0.3: dependency HUnit-1.2.0.3 doesn't exist dependency QuickCheck-1.2.0.0 doesn't exist dependency array-0.2.0.0 doesn't exist dependency base-4.0.0.0 doesn't exist dependency bytestring-0.9.1.4 doesn't exist dependency directory-1.0.0.2 doesn't exist dependency mtl-1.1.0.2 doesn't exist dependency old-locale-1.0.0.1 doesn't exist dependency old-time-1.0.0.1 doesn't exist dependency parsec-2.1.0.1 doesn't exist dependency random-1.0.0.1 doesn't exist dependency template-haskell-2.3.0.0 doesn't exist There are problems in package happstack-data-0.3: dependency HUnit-1.2.0.3 doesn't exist dependency base-4.0.0.0 doesn't exist dependency bytestring-0.9.1.4 doesn't exist dependency containers-0.2.0.0 doesn't exist dependency mtl-1.1.0.2 doesn't exist dependency pretty-1.0.1.0 doesn't exist dependency syb-0.1.0.0 doesn't exist dependency template-haskell-2.3.0.0 doesn't exist There are problems in package happstack-state-0.3: dependency HUnit-1.2.0.3 doesn't exist dependency base-4.0.0.0 doesn't exist dependency bytestring-0.9.1.4 doesn't exist dependency containers-0.2.0.0 doesn't exist dependency directory-1.0.0.2 doesn't exist dependency filepath-1.1.0.1 doesn't exist dependency mtl-1.1.0.2 doesn't exist dependency old-time-1.0.0.1 doesn't exist dependency random-1.0.0.1 doesn't exist dependency stm-2.1.1.2 doesn't exist dependency syb-0.1.0.0 doesn't exist dependency template-haskell-2.3.0.0 doesn't exist dependency unix-2.3.1.0 doesn't exist There are problems in package happstack-ixset-0.3: dependency HUnit-1.2.0.3 doesn't exist dependency base-4.0.0.0 doesn't exist dependency containers-0.2.0.0 doesn't exist dependency mtl-1.1.0.2 doesn't exist dependency syb-0.1.0.0 doesn't exist dependency template-haskell-2.3.0.0 doesn't exist There are problems in package happstack-server-0.3: dependency HUnit-1.2.0.3 doesn't exist dependency base-4.0.0.0 doesn't exist dependency bytestring-0.9.1.4 doesn't exist dependency containers-0.2.0.0 doesn't exist dependency directory-1.0.0.2 doesn't exist dependency html-1.0.1.2 doesn't exist dependency mtl-1.1.0.2 doesn't exist dependency old-locale-1.0.0.1 doesn't exist dependency old-time-1.0.0.1 doesn't exist dependency parsec-2.1.0.1 doesn't exist dependency syb-0.1.0.0 doesn't exist dependency template-haskell-2.3.0.0 doesn't exist dependency unix-2.3.1.0 doesn't exist dependency xhtml-3000.2.0.1 doesn't exist There are problems in package happstack-contrib-0.3: dependency HUnit-1.2.0.3 doesn't exist dependency base-4.0.0.0 doesn't exist dependency bytestring-0.9.1.4 doesn't exist dependency directory-1.0.0.2 doesn't exist dependency mtl-1.1.0.2 doesn't exist dependency old-time-1.0.0.1 doesn't exist dependency syb-0.1.0.0 doesn't exist dependency unix-2.3.1.0 doesn't exist There are problems in package FileManip-0.3.2: dependency base-3.0.3.0 doesn't exist dependency bytestring-0.9.1.4 doesn't exist dependency directory-1.0.0.2 doesn't exist dependency filepath-1.1.0.1 doesn't exist dependency mtl-1.1.0.2 doesn't exist dependency unix-2.3.1.0 doesn't exist There are problems in package happstack-0.3: dependency HUnit-1.2.0.3 doesn't exist dependency base-4.0.0.0 doesn't exist dependency bytestring-0.9.1.4 doesn't exist dependency directory-1.0.0.2 doesn't exist dependency filepath-1.1.0.1 doesn't exist dependency mtl-1.1.0.2 doesn't exist dependency old-time-1.0.0.1 doesn't exist dependency syb-0.1.0.0 doesn't exist There are problems in package HTTP-4000.0.5: dependency array-0.2.0.0 doesn't exist dependency base-3.0.3.0 doesn't exist dependency bytestring-0.9.1.4 doesn't exist dependency mtl-1.1.0.2 doesn't exist dependency old-time-1.0.0.1 doesn't exist dependency parsec-2.1.0.1 doesn't exist There are problems in package haddock-2.4.2: dependency Cabal-1.6.0.3 doesn't exist dependency array-0.2.0.0 doesn't exist dependency base-4.1.0.0 doesn't exist dependency containers-0.2.0.1 doesn't exist dependency directory-1.0.0.3 doesn't exist dependency filepath-1.1.0.2 doesn't exist dependency pretty-1.0.1.0 doesn't exist There are problems in package ghc-6.10.2: dependency Cabal-1.6.0.3 doesn't exist dependency array-0.2.0.0 doesn't exist dependency base-4.1.0.0 doesn't exist dependency bytestring-0.9.1.4 doesn't exist dependency containers-0.2.0.1 doesn't exist dependency directory-1.0.0.3 doesn't exist dependency editline-0.2.1.0 doesn't exist dependency filepath-1.1.0.2 doesn't exist dependency hpc-0.5.0.3 doesn't exist dependency old-time-1.0.0.2 doesn't exist dependency template-haskell-2.3.0.1 doesn't exist dependency unix-2.3.2.0 doesn't exist The following packages are broken, either because they have a problem listed above, or because they depend on a broken package. CC-delcont-0.2 terminfo-0.2.2.1 darcs-2.2.0 extensible-exceptions-0.1.1.0 binary-0.4.4 syb-with-class-0.4 hspread-0.3.1 happstack-state-0.1 happstack-ixset-0.1 happstack-server-0.1 happstack-contrib-0.1 X11-1.4.5 xmonad-0.8.1 utf8-string-0.3.4 X11-xft-0.3 ghc-paths-0.1.0.5 haddock-2.4.1 regex-base-0.93.1 regex-posix-0.94.1 regex-compat-0.92 syb-with-class-0.5.1 terminfo-0.3 time-1.1.2.3 xmonad-contrib-0.8.1 wxcore-0.11.0 process-1.0.1.1 darcs-2.2.1 haskell98-1.0.1.0 HaXml-1.13.3 terminfo-0.3.0.1 hslogger-1.0.7 happstack-util-0.1 happstack-data-0.1 happstack-util-0.1.9 happstack-data-0.1.9 happstack-state-0.1.9 happstack-ixset-0.1.9 MaybeT-0.1.2 zlib-0.5.0.0 happstack-server-0.1.9 happstack-contrib-0.1.9 HJavaScript-0.4.4 cpphs-1.6 harp-0.4 haskell-src-exts-0.4.8 hsx-0.4.8 HJScript-0.4.4 hsp-0.4.5 happstack-0.1.9 Xauth-0.1 byteorder-1.0.0 xhb-0.2.2009.2.21 HStringTemplate-0.4.3 happstack-util-0.2.1 happstack-data-0.2.1 happstack-ixset-0.2.1 happstack-server-0.2.1 happstack-state-0.2.1 happstack-0.2.1 uniplate-1.2.0.3 wx-0.11.0 wx-0.11.1.2 bimap-0.2.4 encoding-0.5.1 fclabels-0.1 hscolour-1.11 parsec-3.0.0 pureMD5-0.2.4 salvia-0.1.1 salvia-extras-0.1.1 Diff-0.1.2 clevercss-0.1.1 datetime-0.1 nano-md5-0.1.2 network-2.2.0.1 split-0.1.1 xml-1.3.4 filestore-0.2 hsemail-1.3 SMTPClient-1.0.1 HTTP-4000.0.4 happstack-util-0.3 happstack-data-0.3 happstack-state-0.3 happstack-ixset-0.3 happstack-server-0.3 happstack-contrib-0.3 FileManip-0.3.2 happstack-0.3 HTTP-4000.0.5 haddock-2.4.2 ghc-6.10.2 Did I do something wrong in the installation step? thanks ... -deech

1 0

Re: [Haskell-beginners] generating the set of all finite-valued ...
by Erik Quaeghebeur 28 Apr '09

28 Apr '09

> On Thu, Apr 23, 2009 at 03:45:27PM +0200, Erik Quaeghebeur wrote: >> >> I'd like to lazily generate the set of all {-1,0,1}-valued functions on >> {'a','b','c'}? How should I best approach this. I was thinking about >> generalizing the power set definition On Thu, 23 Apr 2009, Jan Jakubuv wrote: > > Try to start with this: > > mapM (\x -> [(x,-1),(x,0),(x,1)]) ['a','b','c'] Aha. Great. Thanks, Jan. And now I realized that I don't really care about the domain, so I said: Prelude> let m = mapM (\x -> [(x,-1),(x,0),(x,1)]) ['a','b','c'] Prelude> map (\x -> snd $ unzip x) m [[-1,-1,-1],[-1,-1,0],[-1,-1,1],[-1,0,-1],[-1,0,0],[-1,0,1],[-1,1,-1],[-1,1,0],[-1,1,1],[0,-1,-1],[0,-1,0],[0,-1,1],[0,0,-1],[0,0,0],[0,0,1],[0,1,-1],[0,1,0],[0,1,1],[1,-1,-1],[1,-1,0],[1,-1,1],[1,0,-1],[1,0,0],[1,0,1],[1,1,-1],[1,1,0],[1,1,1]] Any more direct way of doing this? (Still trying to understand how the mapM works... I've found it's sequence.map, but that doesn't really help.) The next step will be to choose a good data format for what I'm trying to achieve. The functions (now represented as lists) would more naturally be represented as column matrices, e.g., from Numeric.LinearAlgebra of hmatrix, as I'll be needing some linear system solver. I can do the transition from lists to that, but I'm afraid they don't give me the necessary flexibility; I'd need to filter them based on (maximum/minimum) component values and sum them and such. Any thoughts on that? Erik

4 4