Re: [Haskell-cafe] Poll plea: State of GUI graphics libraries in Haskell
What does the following mean? About three years ago, I built a modern replacement of my old Pan and Vertigo systems (optimized high-level functional graphics in 2D and 3D), generating screamingly fast GPU rendering code. I'd love to share it with the community, but I'm unable to use it even myself. Casey On Thu, Sep 26, 2013 at 8:32 PM, Conal Elliott co...@conal.net wrote: I'm polling to see whether there are will and expertise to reboot graphics and GUIs work in Haskell. I miss working on functional graphics and GUIs in Haskell, as I've been blocked for several years (eight?) due to the absence of low-level foundation libraries having the following properties: * cross-platform, * easily buildable, * GHCi-friendly, and * OpenGL-compatible. The last several times I tried Gtk2hs, I was unable to compile it on my Mac. Years ago when I was able to compile, the GUIs looked and interacted like a Linux app, which made them awkward and upleasant to use. wxHaskell (whose API and visual appearance I prefered) has for years been incompatible with GHCi, in that the second time I open a top-level window, the host process (GHCi) dies abruptly. Since my GUI graphics programs are often one-liners, and I tend to experiment a lot, using a full compilation greatly thwarts my flow. For many years, I've thought that the situation would eventually improve, since I'm far from the only person who wants GUIs or graphics from Haskell. About three years ago, I built a modern replacement of my old Pan and Vertigo systems (optimized high-level functional graphics in 2D and 3D), generating screamingly fast GPU rendering code. I'd love to share it with the community, but I'm unable to use it even myself. Two questions: * Am I mistaken about the current status? I.e., is there a solution for Haskell GUI graphics programming that satisfies the properties I'm looking for (cross-platform, easily buildable, GHCi-friendly, and OpenGL-compatible)? * Are there people willing and able to fix this situation? My own contributions would be to test and to share high-level composable and efficient GUI and graphics libraries on top of a working foundation. Looking forward to replies. Thanks, -- Conal ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Alternative name for return
I thought a pure value was being returned from the monad. :) On Mon, Aug 5, 2013 at 10:32 PM, Christian Sternagel c.sterna...@gmail.comwrote: Dear Jurriën. personally, I like lift (which is of course already occupied in Haskell), since an arbitrary value is lifted into a monad. (The literature sometimes uses unit.) cheers chris On 08/06/2013 02:14 PM, J. Stutterheim wrote: Dear Cafe, Suppose we now have the opportunity to change the name of the `return` function in Monad, what would be a better name for it? (for some definition of better) N.B. I am _not_ proposing that we actually change the name of `return`. I do currently have the opportunity to pick names for common functions in a non-Haskell related project, so I was wondering if there perhaps is a better name for `return`. - Jurriën __**_ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/**mailman/listinfo/haskell-cafehttp://www.haskell.org/mailman/listinfo/haskell-cafe __**_ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/**mailman/listinfo/haskell-cafehttp://www.haskell.org/mailman/listinfo/haskell-cafe -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] memoization
Have you tried the compiler? On Sun, Jul 21, 2013 at 11:59 PM, Christopher Howard christopher.how...@frigidcode.com wrote: When I previously asked about memoization, I got the impression that memoization is not something that just happens magically in Haskell. Yet, on a Haskell wiki page about Memoizationhttp://www.haskell.org/haskellwiki/Memoization#Memoization_with_recursion, an example given is memoized_fib :: Int - Integer memoized_fib = (map fib [0 ..] !!) where fib 0 = 0 fib 1 = 1 fib n = memoized_fib (n-2) + memoized_fib (n-1) I guess this works because, for example, I tried memoized_fib 1 and the interpreter took three or four seconds to calculate. But every subsequent call to memoized_fib 1 returns instantaneously (as does memoized_fib 10001). Could someone explain the technical details of why this works? Why is map fib [0 ..] not recalculated every time I call memoized_fib? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] There was someone here going to use REPA and a functional way to find eigenvalues :)
Have you succeeded? In general, is there a functional way to do matrix manipulations? Linear algebra? Linear programming? Integer Programming? Numerical Analysis? Casey -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Do combinatorial algorithms have a matroid strucutre XOR non-matroid structure?
I ask this on this mailing list because there are quite a few mathematically oriented people here. Casey -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Is the following implemented by a sparse matrix representation? type Graph n w = Array (n, n) (Maybe w)
Thank you :) On Wed, Jul 10, 2013 at 8:33 AM, Twan van Laarhoven twa...@gmail.comwrote: The standard array types, such as Array (n,n) (Maybe w) will be implemented as a dense array. If you want to use a sparse matrix, you will explicitly have to ask for it. For instance by using something like IntMap (IntMap w) or Map (n,n) w or Array n (IntMap w). Each of these representations is slightly different, and there will be different trade-offs. Twan On 09/07/13 23:26, KC wrote: Is the following implemented by a sparse matrix representation? type Graph n w = Array (n,n) (Maybe w) -- -- Regards, KC __**_ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/**mailman/listinfo/haskell-cafehttp://www.haskell.org/mailman/listinfo/haskell-cafe -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Is the following implemented by a sparse matrix representation? type Graph n w = Array (n, n) (Maybe w)
type Graph n w = Array (n,n) (Maybe w) -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Will Haskell Platform 2012.4.0.0 uninstall cleanly for the installation of 2013.2.0.0
:) -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Mobile app development?
You would need native compilers for all the platforms and/or virtual machine technology. Might be easier to have the browser connect to a Haskell app. On Sat, Jan 19, 2013 at 10:42 AM, Andrew Pennebaker andrew.penneba...@gmail.com wrote: There are currently very few options, especially free and open source options, when it comes to developing cross-platform mobile applications. It's basically web apps with JavaScript, or C++. If Haskell supported app development on Android, iOS, and Windows RT, that alone would bring in more developers. Similarly, there are very few languages for mobile development that take advantage of multiple cores and multiple CPUs. Haskell's `parmap` is an amazing selling point. Can we please prioritize mobile support? I'd much rather write everything in ML than PhoneGap. -- Cheers, Andrew Pennebaker www.yellosoft.us ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Mobile app development?
Then it looks as if the easier implementation would be small Haskell VM's for the various platforms with a byte code compiler. I do not believe the JVM supports all the optimizations GHC can do. Oh wait! Can the LLVM be easily ported to do this? On Sat, Jan 19, 2013 at 11:40 AM, Andrew Pennebaker andrew.penneba...@gmail.com wrote: Might be easier to have the browser connect to a Haskell app. Not all apps can be run as thin clients. 3D video games and other intensive programs aren't easily done as thin clients. Mobile Haskell would be very powerful, because concurrency and parallelism aren't something the C-family languages are supporting that well. On Sat, Jan 19, 2013 at 10:42 AM, Andrew Pennebaker andrew.penneba...@gmail.com wrote: There are currently very few options, especially free and open source options, when it comes to developing cross-platform mobile applications. It's basically web apps with JavaScript, or C++. If Haskell supported app development on Android, iOS, and Windows RT, that alone would bring in more developers. Similarly, there are very few languages for mobile development that take advantage of multiple cores and multiple CPUs. Haskell's `parmap` is an amazing selling point. Can we please prioritize mobile support? I'd much rather write everything in ML than PhoneGap. -- Cheers, Andrew Pennebaker www.yellosoft.us ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- -- Regards, KC -- Cheers, Andrew Pennebaker www.yellosoft.us -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Is http://hackage.haskell.org/packages/hackage.html having a challenging serving up archive.tar?
:) -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Are there REPA linear algebra routines? e.g. Eigenvalues?
:) -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Why is boxed mutable array so slow?
Boxed arrays have a wrapper (extra layer of indirection) to allow for
a fully evaluated value, an unevaluated thunk, or the special value
bottom (a value that can contain bottom is referred to as lifted).
Unboxed arrays always have some value; that is, they cannot represent
a thunk nor bottom.
On Sat, Dec 1, 2012 at 8:09 AM, Branimir Maksimovic bm...@hotmail.com wrote:
I have made benchmark test inspired by
http://lemire.me/blog/archives/2012/07/23/is-cc-worth-it/
What surprised me is that unboxed array is much faster than boxed array.
Actually boxed array performance is on par with standard Haskell list
which is very slow.
All in all even unboxed array is about 10 times slower than Java version.
I don't understand why is even unboxed array so slow.
But! unboxed array consumes least amount of RAM.
(warning, program consumes more than 3gb of ram)
bmaxa@maxa:~/examples$ time ./Cumul
boxed array
last 262486571 seconds 4.972
unboxed array
last 262486571 seconds 0.776
list
last 262486571 seconds 6.812
real0m13.086s
user0m11.996s
sys 0m1.080s
-
{-# LANGUAGE CPP, BangPatterns #-}
import System.CPUTime
import Text.Printf
import Data.Array.IO
import Data.Array.Base
import Data.Int
import Control.DeepSeq
import System.Mem
main :: IO()
main = do
(newArray_ (0,n'-1) :: IO(A)) = test boxed array
performGC
(newArray_ (0,n'-1) :: IO(B)) = test unboxed array
performGC
begin - getCPUTime
printf list\nlast %d $ last $ force $ take n' $ sum' data'
end - getCPUTime
let diff = (fromIntegral (end - begin)) / (10^12)
printf seconds %.3f\n (diff::Double)
test s a = do
putStrLn s
begin - getCPUTime
init' a
partial_sum a
end - getCPUTime
let diff = (fromIntegral (end - begin)) / (10^12)
last - readArray a (n'-1)
printf last %d seconds %.3f\n last (diff::Double)
n' :: Int
n' = 50 * 1000 * 1000
type A = IOArray Int Int32
type B = IOUArray Int Int32
init' a = do
(_,n) - getBounds a
init a 0 n
where
init a k n
| k n = return ()
| otherwise = do
let !x = fromIntegral $ k + k `div` 3
unsafeWrite a k x
init a (k+1) n
partial_sum a = do
(_,n) - getBounds a
k - unsafeRead a 0
ps a 1 n k
where
ps a i n s
| i n = return ()
| otherwise = do
k - unsafeRead a i
let !l = fromIntegral $ s + k
unsafeWrite a i l
ps a (i+1) n l
data' :: [Int32]
data' = [k + k `div` 3 | k - [0..] ]
sum' = scanl1 (+)
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--
--
Regards,
KC
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Re: [Haskell-cafe] How to incrementally update list
Why do you want to incrementally update this list a lot of times? The question would affect the answer you get; i.e. some context (non-monadically speaking). :D On Wed, Nov 28, 2012 at 3:43 AM, Branimir Maksimovic bm...@hotmail.com wrote: Problem is following short program: list = [1,2,3,4,5] advance l = map (\x - x+1) l run 0 s = s run n s = run (n-1) $ advance s main = do let s = run 5000 list putStrLn $ show s I want to incrementally update list lot of times, but don't know how to do this. Since Haskell does not have loops I have to use recursion, but problem is that recursive calls keep previous/state parameter leading to excessive stack.and memory usage. I don't know how to tell Haskell not to keep previous state rather to release so memory consumption becomes managable. Is there some solution to this problem as I think it is rather common? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Compilers: Why do we need a core language?
I believe the question you are asking is why do large software systems need to be designed in terms of levels or some other software engineering construct(s). To manage their complexity as opposed to getting mangled in their complexity. :D -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] To cabal install cabal-install on Windows ...
- completely remove the earlier Haskell Platform - reboot - defragment the partition/hard drive - reboot - install the newer Haskell Platform - reboot - defragment the partition/hard drive (recommended) - reboot - cabal update - cabal install cabal-install It seems like what is slowing down the install process (or hanging it) is the thrashing of your hard drive to find all the little file fragments it needs during the install Casey -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] code length in Haskell, a comparison
I am leery of code comparisons (but not Timothy Leary of them). Clojure being a JVM language has the advantage of the massive Java class libraries. If Haskell could tie in fairly seamlessly to the Java class libraries ... If more developers learned the need for finer grained abstraction ... On Mon, Nov 19, 2012 at 7:55 PM, Gregory Guthrie guth...@mum.edu wrote: There is some interesting data in the article at: Code Length Measured in 14 Languages http://blog.wolfram.com/2012/11/14/code-length-measured-in-14-languages/ basically comparing program lengths in various languages, and some ensuing discussion of how this relates to language expressiveness, etc. (He does all of his analysis in Mathematica, which is the goal of the article.) It is interesting to see how well Haskell showed in the data; and it would also be interesting to see how well it could replicate the analysis example which was a nice example of web data scraping! The data is the length of a series of programs written in a number of languages (data from: http://rosettacode.org/wiki/Rosetta_Code). (The columns don't map well to text only, Haskell column marked with (Why doesn't this list support HTML?)). See nicer version at: http://pastehtml.com/view/ciy7woohv.rtxt The average for Haskell of 1.89 means that on the average the same program in Haskell takes ~2x in the other languages. Given the correlation of size to clarity, complexity, effort, and errors, this is a good thing! :-) Massive Snip! Overall Ranking: Clojure 0.41 Haskell 0.83 R0.85 MATLAB 1.14 JavaScript 1.27 Ruby 1.36 Common Lisp 1.56 Python 1.61 C++ 1.68 C# 1.85 Pascal 1.86 Fortran 2.33 C++ 2.58 C4.09 --- ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Instead of Haskell running on the JVM is there a way for Haskell to call a JVM language ...
Instead of Haskell running on the JVM is there a way for Haskell to call a JVM language (or generate bytecode) to access the Java class libraries when needed? Or Is there a way for a JVM language or bytecode to call Haskell when needed? -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Tutorial: Haskell for the Evil Genius
The latest Haskell Platform is 2012.2.0.0 You are apparently running a much older version. #!c:/Program Files/Haskell Platform/2010.2.0.0/bin/ runhaskell -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] What is a functional approach to linear algebra routines? I see REPA warns that one must use fusion or risk slow routines.
Apparently using STUarrays in an imperative fashion is fraught with peril (and the performance of molasses). Casey -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] One of the new buzz phrases is Event-Sourcing; is Haskell suitable for this?
http://martinfowler.com/eaaDev/EventSourcing.html http://martinfowler.com/articles/lmax.html -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] If I want to make a pure Haskell eigenvalue, etc. package without calling to LAPACK, etc ...
What are some good basis (pun intended) to start from? e.g. REPA? or ? -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Monads
From: http://www.haskell.org/haskellwiki/Monad The computation doesn't have to be impure and can be pure itself as well. Then monads serve to provide the benefits of separation of concerns, and automatic creation of a computational pipeline. On Sat, Sep 29, 2012 at 6:57 PM, Vasili I. Galchin vigalc...@gmail.com wrote: Hello, I would an examples of monads that are pure, i.e. no side-effects. Thank you, Vasili ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Haskell seems setup for iterative numerics; i.e. a standard example is Newton's method where lazy evaluation ...
separates control from computation. It seems as if Haskell would be better for iterative matrix methods rather than direct calculation. -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskell seems setup for iterative numerics; i.e. a standard example is Newton's method where lazy evaluation ...
The REPA package/library doesn't have LU factorization, eigenvalues, etc. On Wed, Sep 5, 2012 at 12:59 PM, Carter Schonwald carter.schonw...@gmail.com wrote: Hello KC, you should check out the Repa library then and see how it works for you. Cheers -Carter On Wed, Sep 5, 2012 at 12:46 PM, KC kc1...@gmail.com wrote: separates control from computation. It seems as if Haskell would be better for iterative matrix methods rather than direct calculation. -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] hstats median algorithm
Is there any special structure in your data that could be exploited? On Sat, Sep 1, 2012 at 6:17 PM, Gershom Bazerman gersh...@gmail.com wrote: In my experience, doing much better than the naive algorithm for median is surprisingly hard, and involves a choice from a range of trade-offs. Did you have a particular better algorithm in mind? If you did, you could write it, and contact the package author with a patch. You also may be able to find something of use in Edward Kmett's order-statistics package: http://hackage.haskell.org/package/order-statistics Cheers, Gershom On 9/1/12 3:26 PM, David Feuer wrote: The median function in the hstats package uses a naive O(n log n) algorithm. Is there another package providing an O(n) option? If not, what would it take to get the package upgraded? -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Is it worth adding Gaussian elimination and eigenvalues to REPA?
I realize if one wants speed you probably want to use the hMatrix interface to GSL, BLAS and LAPACK. Worth it in the sense of have a purely functional implementation. -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Does someone have a compiled binary of the LLVM for Windows 7 or must one compile the source?
Thank you It involves going to - path\cabal\packages\hackage.haskell.org\repa-algorithms\3.2.1.1\repa-algorithms-3.2.1.1 - making the cabal file changes - re-tar-ing - re-gzip-ing On Wed, Aug 15, 2012 at 6:29 PM, Ivan Lazar Miljenovic ivan.miljeno...@gmail.com wrote: On 16 August 2012 11:21, KC kc1...@gmail.com wrote: I just want to get started on some matrix operations with REPA. Or is there a library (package?) like REPA without using the LLVM? If you're referring to your recent problems with repa-algorithms, you can try this: cabal unpack repa-algorithms # Not sure of the syntax for changing directories in the cmd.exe terminal cd repa-algorithms-version # Use a text editor to remove the line -fllvm from the .cabal file cabal install -- -- Regards, KC -- Ivan Lazar Miljenovic ivan.miljeno...@gmail.com http://IvanMiljenovic.wordpress.com -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Does someone have a compiled binary of the LLVM for Windows 7 or must one compile the source?
I just want to get started on some matrix operations with REPA. Or is there a library (package?) like REPA without using the LLVM? -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] For consistency; it would be better if the import statement matched the cabal install statement or :m form.
:m +Data.Array.Repa.Algorithms.Randomish cabal install repa.algrothms would be more consistent. -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] I use cabal install repa but then WinGHCi says module Data.Array.Rep.Algorithms.Ramdomish not found.
The install of repa-algorithms fails saying it can't cannot find an llvm. In any case why can't the install syntax be cabal install repa.algorithms then it would be more consistent with the import statement. On Sun, Aug 12, 2012 at 4:00 PM, Ivan Lazar Miljenovic ivan.miljeno...@gmail.com wrote: I think you need to install repa-algorithms. On 13 August 2012 04:18, KC kc1...@gmail.com wrote: -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- Ivan Lazar Miljenovic ivan.miljeno...@gmail.com http://IvanMiljenovic.wordpress.com -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] I use cabal install repa but then WinGHCi says module Data.Array.Rep.Algorithms.Ramdomish not found.
-- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] [Haskell-beginners] vector indexing time
Thank you for that insight. :) On Fri, Aug 3, 2012 at 4:50 AM, Heinrich Apfelmus apfel...@quantentunnel.de wrote: Creating the vector still takes time proportional to the length of the vector. In fact, it appears that in your example, the vector packages optimizes the creation time to create only up to the element that you actually demand. The linear time you're seeing is not the result of an inefficiency of vector indexing, but the result of an efficiency in vector creation. Best regards, Heinrich Apfelmus -- http://apfelmus.nfshost.com -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Why is the the transpose function in Data.List more complicated?
Transpose in Data.List is the following: transpose :: [[a]] - [[a]] transpose [] = [] transpose ([] : xss) = transpose xss transpose ((x:xs) : xss) = (x : [h | (h:_) - xss]) : transpose (xs : [ t | (_:t) - xss]) Yet this seems to work. transp :: [[b]] - [[b]] transp ([]:_) = [] transp rows = map head rows : transp (map tail rows) Why is the the transpose function in Data.List more complicated? -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] The following is supposed to be initializing a 2D array but it doesn't seem to work.
newArr :: (Ix i) = i - i - e - Array i e newArr n m x = listArray (n,m) (repeat http://haskell.org/ghc/docs/latest/html/libraries/base/Prelude.html#v:repeat x) - Prelude http://haskell.org/ghc/docs/latest/html/libraries/base/Prelude.html Data.Array newArr 0 10 0 array (0,10) [(0,0),(1,0),(2,0),(3,0),(4,0),(5,0),(6,0),(7,0),(8,0),(9,0),(10,0)] Prelude http://haskell.org/ghc/docs/latest/html/libraries/base/Prelude.html Data.Array newArr (0,0) (5,5) 0 array ((0,0),(5,5)) [((0,0),0),((0,1),0),((0,2),0),((0,3),0),((0,4),0),((0,5),0),((1,0),0),((1,1),0),((1,2),0),((1,3),0),((1,4),0),((1,5),0),((2,0),0),((2,1),0),((2,2),0),((2,3),0),((2,4),0),((2,5),0),((3,0),0),((3,1),0),((3,2),0),((3,3),0),((3,4),0),((3,5),0),((4,0),0),((4,1),0),((4,2),0),((4,3),0),((4,4),0),((4,5),0),((5,0),0),((5,1),0),((5,2),0),((5,3),0),((5,4),0),((5,5),0)] All I am getting is this: array ((1,5),(1,5)) [((1,5),1.0)] Maybe the behaviour of ghc was changed since the article was written. -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] The following is supposed to be initializing a 2D array but it doesn't seem to work.
That was it! On Tue, Jul 31, 2012 at 3:34 PM, Jan-Willem Maessen jmaes...@alum.mit.eduwrote: On Tue, Jul 31, 2012 at 5:52 PM, KC kc1...@gmail.com wrote: All I am getting is this: array ((1,5),(1,5)) [((1,5),1.0)] Maybe the behaviour of ghc was changed since the article was written. I think you've made a common mistake here. Array bounds are (lower in all dimensions, upper in all dimensions). So perhaps you intended to use the bounds ((1,1), (5,5)) in your code? I make this mistake frequently. -Jan-Willem Maessen -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] I can see lists working for matrix algorithms if the access patterns are mostly from the start or end of rows and columns.
Are there any such matrix algorithms that operate mainly from the start or end or rows and columns? Note: If the access pattern starts from the end of a row then one stores the row in reverse order in a list. -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] [Haskell-beginners] Graph Coloring Library?
On Hackage there is the Graphalyze package but it doesn't seem to do vertex coloring. Are you talking about undirected graphs? On Sat, Jul 14, 2012 at 12:23 PM, Alec Story av...@cornell.edu wrote: I'd prefer an exact solution, but it doesn't have to be particularly performant (this is research code). The graphs are pretty small in general, all my test cases will have 10 nodes, but have high connectivity. They don't have any special properties. On Jul 14, 2012 2:50 PM, KC kc1...@gmail.com wrote: Are you looking for an exact or approximate solution. How many nodes and edges? Any special properties that the graph has? On Fri, Jul 13, 2012 at 1:43 PM, Alec Story av...@cornell.edu wrote: I have a problem where I need to find the smallest k-coloring for a graph that represents conflicts between objects. Is there a Haskell library that will do this for me? I'm not particularly concerned about speed, and it's unlikely that I'll generate really bad edge cases, but I'd prefer to do something other than write the really bad try-every-case algorithm. -- Alec Story Cornell University Biological Sciences, Computer Science 2012 ___ Beginners mailing list beginn...@haskell.org http://www.haskell.org/mailman/listinfo/beginners -- -- Regards, KC -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] [Haskell-beginners] Graph Coloring Library?
This may help: - use hMatrix to find the eigenvalues of the adjacency matrix Then by the following theorems: An upper bound on the chromatic number in terms of eigenvalues was discovered by Wilf(1967). Chromatic Number(G) = 1 + lambda_1(G) Hoffman (1977) discovered a lower bound on the chromatic number in terms of the smallest and largest eigenvalue. Chromatic Number(G) = 1 - (lambda_1/lambda_n) for n=2. From The Mutually Beneficial Relationship of Graphs and Matrices, Richard A. Brualdi,CBMS Series,Number 115, 2011. On Fri, Jul 13, 2012 at 1:43 PM, Alec Story av...@cornell.edu wrote: I have a problem where I need to find the smallest k-coloring for a graph that represents conflicts between objects. Is there a Haskell library that will do this for me? I'm not particularly concerned about speed, and it's unlikely that I'll generate really bad edge cases, but I'd prefer to do something other than write the really bad try-every-case algorithm. -- Alec Story Cornell University Biological Sciences, Computer Science 2012 ___ Beginners mailing list beginn...@haskell.org http://www.haskell.org/mailman/listinfo/beginners -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] There is some article mentioning that FP is mainly good for mathematical and list programming.
There is some article mentioning that functional programming is mainly good for mathematical programming and list programming because otherwise it is to cryptic for business and database applications. Being semi-intelligent, I thought I could reduce what others think of as cryptic but maybe instead of 18 wheels I have only 17 wheels. :D -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Best way to build a GHC backend?
As to your porting of Haskell to the JVM question; the JVM would be unable to perform all the optimizations that GHC can do. There is really not much point in running slow code. JavaScript is interesting since the JIT compiler gets better all the time. On Sat, Jul 7, 2012 at 10:02 PM, Jonathan Geddes geddes.jonat...@gmail.comwrote: Venerable Haskell Hackers, I love Haskell and think it should run everywhere. Now supposing I would like to build another backend for GHC, perhaps for Java Bytecode, .Net CIL, or JavaScript, What would be the best way to approach that? I can think of a few options: 1. Produce External Core with -fext-core and compile that with a completely separate compiler 2. Use the GHC apis to build a compiler that reuses a load of GHC's code, but has it's own backend 3. Add a new backend directly into GHC Any other options? While I'm on the subject, why has Haskell not been ported to the likes of the JVM, .NET CLR, or JavaScript? Are Haskell's non-strict semantics just too different from the semantics of these other platforms? SPJ is known for saying that Haskell's plan for world domination is support for many parallelism/concurrency idioms. I believe running on many platforms is just as important. From my point of view, languages that cannot run on one of the 3 aforementioned platforms will become irrelevant. (with the exception of C, of course). Thoughts? --J Arthur ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Is there a GHC flag that will allow mutable top level state while you are debugging and then ...
you can turn the flag off when you are ready to do the computational heavy lifting so that you don't have to modify your code base? That is, GHC can then apply its algebraic transformation optimizations to the code algebra of the pure functions. -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] [Haskell-beginners] Function application versus function composition performance
A good functional programming language has a good code algebra after parsing to which algebraic transformations can be applied for optimization. For example, reducing the need for generating intermediate data structures. See: fusion. On Tue, Jun 19, 2012 at 3:01 PM, Matt Ford m...@dancingfrog.co.uk wrote: Hi All, My last question got me thinking (always dangerous): an expression that doubles a list and takes the 2nd element (index 1), I assume, goes through the following steps. double (double [1,2,3,4]) !! 1 double ( 1*2 : double [2,3,4]) !! 1 1*2*2 : double ( double [2,3,4] ) !! 1 1*2*2 : double ( 2*2 : double [3,4] ) !! 1 1*2*2 : 2*2*2 : double ( double [3,4] ) !! 1 2*2*2 8 Up until the element requested all the proceeding elements have to have the expression formed as Haskell process the calculation. Now, I want to compare this to using function composition ( double . double ) [ 1 ,2, 3, 4 ] !! 1 This is the bit I'm unsure of - what does the composition look like. It is easy to see that it could be simplified to something like: ( double . double) (x:xs) = x*4 : (double . double) xs This would mean the steps could be written (double . double) [ 1,2,3,4 ] !! 1 (1*4 : (double.double) [2,3,4]) !! 1 (1*4 : 2*4 : (double.double) [ 3,4 ]) !! 1 2*4 8 Ignoring the start and end steps, it will be half the number of steps compared to the application version. Significant then, over long lists. So is this true, are composite functions simplified in Haskell in general so that they may have improved performance over function application? I've seen posts on the internet that say it's a matter of style only: http://stackoverflow.com/questions/3030675/haskell-function-composition-and-function-application-idioms-correct-us . But my reasoning suggests it could be more than that. Perhaps, function application is similarly optimised - maybe by replacing all functions applications with composition and then simplifying? Or maybe the simplifying/optimisation step never happens? As you can see I'm just guessing at things :-) But it's nice to wonder. Many thanks for any pointers, Matt. ___ Beginners mailing list beginn...@haskell.org http://www.haskell.org/mailman/listinfo/beginners -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] How to select n random words from a file ...
An interesting related problem is if you are only allowed one pass through the data how would you randomly choose one word. -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Found quote: One of the ineradicable illusions about C++ is that the compiler should be able to see through ...
all the abstractions and obfuscations an “advanced” C++ program contains. First and foremost, C++ should be seen as a language that enables complexity management. The features one has grown fond of in this concept, like operator overloading, object orientation, automatic construction/destruction, etc., are however mostly unsuitable for efficient low-level code. From Introduction to High Performance Computing for Scientists and Engineers CRC Press, 2011. So if one avoids such C++ complexity management features and a Haskell compiler can see through most of the complexity management features of Haskell; they should be comparable. :) Casey -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Most C++ compilers will not optimize x^2.0 as x*x but instead will do an expensive ...
exponentiation and logarithm. So, I believe this C++ versus Haskell versus (your language of choice) is a Penn Teller misdirection. Whereas, another level of indirection solves everything. -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] From some High-Performance Computing book; It is hard to eradicate from C++'ers the need for objects, classes, etc. ...
For high-performance computing you want to avoid such software engineering abstractions as classes, objects, etc Therefore, I would say, since Haskell makes possible many fine-levels of abstraction, if the compiler can strip most of these away, then it would come close to the speed of C (i.e. C++ without most of the software engineering abstractions). Still, I remember that quote that, Another level of indirection solves everything. Or If you're Penn Teller, Another level of misdirection solves everything. Casey -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] I am having trouble with the type declaration for creating an identity matrix.
initIdentityMat :: Int - ST s (STUArray s (Int,Int) ((Int, Int), Double)) initIdentityMat m = newListArray ((1,m),(1,m)) ([((i,j), if i == j then 1.0 else 0.0) | i - [1..m], j - [1..m]] :: [((Int,Int), Double)]) Doesn't seem to compile, nor do minor variations of the type declaration. -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] I am having trouble with the type declaration for creating an identity matrix.
Thank you. One is ONLY supposed to supply the list elements for newListArray which fill the array in increasing order. On Tue, Apr 24, 2012 at 3:21 PM, Kevin Charter kchar...@gmail.com wrote: On Tue, Apr 24, 2012 at 3:20 PM, KC kc1...@gmail.com wrote: initIdentityMat :: Int - ST s (STUArray s (Int,Int) ((Int, Int), Double)) initIdentityMat m = newListArray ((1,m),(1,m)) ([((i,j), if i == j then 1.0 else 0.0) | i - [1..m], j - [1..m]] :: [((Int,Int), Double)]) Doesn't seem to compile, nor do minor variations of the type declaration. If you use Hoogle to find the type and API docs for 'newListArray', I believe you'll be able to figure out what's wrong, but I'll give you a hint. The list you're giving to 'newListArray' contains too much; and the pair you give it is only half correct. Kevin -- Kevin Charter kevin.char...@acm.org -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Is it only one data structure per ST monad?
Is it only one data structure per ST monad? -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] (no subject)
buildPair = do arr - newArray ((1,1),(1,10)) 37 :: ST s (STArray s (Int,Int) Int) a - readArray arr (1,1) writeArray arr (1,1) 64 b - readArray arr (1,1) return (a,b) main = print $ runST buildPair -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] The last statement in a 'do' construct must be an expression: a - readArray arr (1, 1)
I'm getting the above error message and I cannot figure out why? buildPair = do arr - newArray ((1,1),(1,10)) 37 :: ST s (STArray s (Int,Int) Int) a - readArray arr (1,1) writeArray arr (1,1) 64 b - readArray arr (1,1) return (a,b) main = print $ runST buildPair -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] The last statement in a 'do' construct must be an expression: a - readArray arr (1, 1)
Thank you, that was it. I was mixing up and tabs and spaces. I expected new versions of NotePad++ to keep my old settings. On Mon, Apr 23, 2012 at 1:54 PM, Ryan Yates fryguy...@gmail.com wrote: Perhaps you are mixing tabs and spaces? On Mon, Apr 23, 2012 at 4:52 PM, KC kc1...@gmail.com wrote: I'm getting the above error message and I cannot figure out why? buildPair = do arr - newArray ((1,1),(1,10)) 37 :: ST s (STArray s (Int,Int) Int) a - readArray arr (1,1) writeArray arr (1,1) 64 b - readArray arr (1,1) return (a,b) main = print $ runST buildPair -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] why are applicative functors (often) faster than monads? (WAS Google Summer of Code - Lock-free data structures)
Think of the differences (and similarities) of Applicative Functors and Monads and the extra context that monads carry around. -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] why are applicative functors (often) faster than monads? (WAS Google Summer of Code - Lock-free data structures)
Sorry, I thought you or someone was asking why are Applicative Functors faster in general than Monads. Functional programming is structured function calling to achieve a result where the functions can be evaluated in an unspecified order; I thought Applicative Functors had the same unspecified evaluation order; whereas, Monads could carry some sequencing of computations which has the extra overhead of continuation passing. Do I have that correct? On Fri, Apr 20, 2012 at 4:05 PM, Ben midfi...@gmail.com wrote: i'm not sure what your email is pointing at. if it is unclear, i understand the difference between applicative and monadic. i suppose the easy answer to why applicative can be faster than monadic is that you can give a more specialized instance declaration. i was just wondering if there was a way to make a monad recognize when it is being used applicatively, but that is probably hard in general. b On Apr 20, 2012, at 2:54 PM, KC wrote: Think of the differences (and similarities) of Applicative Functors and Monads and the extra context that monads carry around. -- -- Regards, KC -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] I Need a Better Functional Language!
On Thu, Apr 5, 2012 at 11:59 AM, Tillmann Rendel ren...@informatik.uni-marburg.de wrote: Paul R wrote: I am curious what are interesting use-cases for that? Symbolic analysis? self-compilers? Optimization. For example, imagine the following definition of function composition: map f . map g = map (f . g) f . g = \x - f (g x) In Haskell, we cannot write this, because we cannot pattern match on function calls. Tillmann So, we're not talking about optimization as in Mathematical Programming but optimization in language constructs. You might want to take a look at MIN by Stephen Tse. -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Theoretical question: are side effects necessary?
Apparently on such solid ground that you hinder their critical thinking skills by answering for them. On Fri, Mar 16, 2012 at 9:24 PM, Donn Cave d...@avvanta.com wrote: Quoth KC kc1...@gmail.com, On Fri, Mar 16, 2012 at 7:44 PM, Jerzy Karczmarczuk jerzy.karczmarc...@unicaen.fr wrote: ... but the question of purity of a program - in my opinion - concerns the program, and nothing else. You might be thinking of software engineering purity. Or software engineers might be thinking of purity in the same way. I personally hope I think of purity in a way that's of some practical use in terms of Haskell programs, and I would hope software engineers in general would do likewise. From that perspective, it seems to me that M. Karczmarczuk is on pretty solid ground. Donn -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] In Haskell, because of the fine layers of abstraction that are possible, it pays to hone one's critical thinking skills.
-- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] In an imperative language, commands fulling memory cells is easy, but gives the false impression that S/W engineering is easy.
-- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Are side effects necessary is a non question; you compute so as to change the state of the world.
Casey -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] The Theoretical Question would be; are side effects necessary for computational heavy lifting.
Casey -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Theoretical question: are side effects necessary?
On Fri, Mar 16, 2012 at 7:44 PM, Jerzy Karczmarczuk jerzy.karczmarc...@unicaen.fr wrote: ... but the question of purity of a program - in my opinion - concerns the program, and nothing else. You might be thinking of software engineering purity. The networking is not expected to break the referential transparency, or does it? Jerzy Karczmarczuk What does referential transparency mean to you? -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] I've just heard of a neat security measure that when you compile the code it generates different object code...
... with the same functionality. Thus, your program would be a moving target to hackers. Would this be challenging with ghc? -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Quicksort in Haskell
What is your question? On Mon, Nov 7, 2011 at 9:45 AM, yrazes yra...@gmail.com wrote: module Main (main) where quicksort [] = [] quicksort (s:xs) = quicksort [x|x - xs,x s] ++ [s] ++ quicksort [x|x - xs,x = s] main = putStr Ingrese la lista\n [xs] - getLine ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Best bit LIST data structure
Must it be a list? What about a Bloom Filter? On Sun, Oct 9, 2011 at 9:11 AM, Roman Beslik ber...@ukr.net wrote: Yes, if you do not use high-level concepts and optimize everything by hand, it requires a lot of testing. :) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Project Euler: request for comments
You might like this zipping folding version. Explicit recursion has the disadvantage that one has to read the entire function in order to figure out what's going on; whereas using the higher order functions makes things much easier to grasp. listof4tuples xs = (zip4 xs (tail xs) (tail (tail xs)) (tail (tail (tail xs prods xs = map prods4 (listof4tuples xs) prods4 (t,u,v,w) = t*u*v*w maxprods4 xs = maximum $ prods xs On Mon, Aug 29, 2011 at 9:40 AM, Oscar Picasso oscarpica...@gmail.com wrote: Got it. f :: [Int] - Int f (t:u:v:xs) = helper t u v xs helper :: Int - Int - Int - [Int] - Int helper t u v (w:ws) | ws == [] = t*u*v*w | otherwise = max (t*u*v*w) (f (u:v:w:ws)) I tend to overlook mutual recursion in my toolbox. Thanks for the nnlightenment. On Sun, Aug 28, 2011 at 4:54 PM, KC kc1...@gmail.com wrote: Try something like the following: -- Project Euler 11 -- In the 20×20 grid below, four numbers along a diagonal line have been marked in red. -- snip -- The product of these numbers is 26 × 63 × 78 × 14 = 1788696. -- What is the greatest product of four adjacent numbers in any direction (up, down, left, right, or diagonally) in the 20×20 grid? import Data.List -- Doing the one dimensional case. f011 :: [Int] - Int f011 (t:u:v:xs) = f011helper t u v xs f011helper :: Int - Int - Int - [Int] - Int f011helper t u v (w:ws) | ws == [] = t*u*v*w | otherwise = yada nada mada -- What are yada nada mada? -- The 20x20 grid case will become: f0112D :: [[Int]] - Int -- where [[Int]] is a list of lists of rows, columns, major diagonals, minor diagonals. On Sun, Aug 28, 2011 at 5:10 AM, Oscar Picasso oscarpica...@gmail.com wrote: No. The answer I posted is not good. It worked, by chance, on a couple of small examples I tried but it could end up comparing sequence of 4 numbers that where not initially adjacent. On Sun, Aug 28, 2011 at 12:32 AM, Oscar Picasso oscarpica...@gmail.com wrote: Maybe this? f x@(a:b:c:d:[]) = x f (a:b:c:d:e:ys) = if e = a then f (b:c:d:e:ys) else f (a:b:c:d:ys) On Sat, Aug 27, 2011 at 8:26 PM, KC kc1...@gmail.com wrote: Think of the simplest version of the problem that isn't totally trivial. e.g. A one dimensional list of numbers. What would you do? Note: you only want to touch each element once. The 2 dimensional case could be handled by putting into lists: rows, columns, major diagonals, and minor diagonals. This isn't the fastest way of doing the problem but it has the advantage of avoiding indexitis. On Fri, Aug 26, 2011 at 6:15 PM, Oscar Picasso oscarpica...@gmail.com wrote: Like: 20*19*21*18 is bigger than 100*100*3*2 ? If so I need to think about how to formalize it. Thanks for the hint. On Fri, Aug 26, 2011 at 8:55 PM, KC kc1...@gmail.com wrote: Is Problem 11 the 4 consecutive #'s problem? If so what must be true for 4 #'s to have a large product? Hint: x * y * z * 2 is that going to be larger? -- -- Regards, KC -- -- Regards, KC -- -- Regards, KC -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Off-topic: Mathematics and modesty
He said Trying to distinguish first between knowledgeable, wise, guru, wizard, etc. before asking the actual mathematics related question. Beware: the expert X is an unknown quantity spert is a drip under pressure :D On Tue, Aug 30, 2011 at 12:16 PM, Chris Smith cdsm...@gmail.com wrote: On Tue, 2011-08-30 at 20:58 +0200, Jerzy Karczmarczuk wrote: With all my respect: I think I know several mathematicians who learning that a person asking for help begins with trying to distinguish between knowledgeable, and those who just think they are, will simply - to say it politely - refuse to engage. I don't agree with this. It's the most natural thing in the world to listen to an answer and then try to figure out whether the speaker knows what they are talking about or not. Those who expect us to forego that step aren't really engaged in mathematics any more. -- Chris Smith ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Project Euler: request for comments
You also don't need mutual recursion for this explicit recursion since I imagine it would use up more stack space. -- Doing the one dimensional case. f011 :: [Int] - Int f011 (t:u:v:xs) = f011helper t u v xs f011helper :: Int - Int - Int - [Int] - Int f011helper t u v (w:ws) | ws == [] = t*u*v*w | otherwise = max (t*u*v*w) (f011helper u v w ws) -- Note: f011helper does not call f011. On Mon, Aug 29, 2011 at 9:40 AM, Oscar Picasso oscarpica...@gmail.com wrote: Got it. f :: [Int] - Int f (t:u:v:xs) = helper t u v xs helper :: Int - Int - Int - [Int] - Int helper t u v (w:ws) | ws == [] = t*u*v*w | otherwise = max (t*u*v*w) (f (u:v:w:ws)) I tend to overlook mutual recursion in my toolbox. Good going! :) Thanks for the enlightenment. On Sun, Aug 28, 2011 at 4:54 PM, KC kc1...@gmail.com wrote: Try something like the following: -- Project Euler 11 -- In the 20×20 grid below, four numbers along a diagonal line have been marked in red. -- snip -- The product of these numbers is 26 × 63 × 78 × 14 = 1788696. -- What is the greatest product of four adjacent numbers in any direction (up, down, left, right, or diagonally) in the 20×20 grid? import Data.List -- Doing the one dimensional case. f011 :: [Int] - Int f011 (t:u:v:xs) = f011helper t u v xs f011helper :: Int - Int - Int - [Int] - Int f011helper t u v (w:ws) | ws == [] = t*u*v*w | otherwise = yada nada mada -- What are yada nada mada? -- The 20x20 grid case will become: f0112D :: [[Int]] - Int -- where [[Int]] is a list of lists of rows, columns, major diagonals, minor diagonals. -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Project Euler: request for comments
Try something like the following: -- Project Euler 11 -- In the 20×20 grid below, four numbers along a diagonal line have been marked in red. -- snip -- The product of these numbers is 26 × 63 × 78 × 14 = 1788696. -- What is the greatest product of four adjacent numbers in any direction (up, down, left, right, or diagonally) in the 20×20 grid? import Data.List -- Doing the one dimensional case. f011 :: [Int] - Int f011 (t:u:v:xs) = f011helper t u v xs f011helper :: Int - Int - Int - [Int] - Int f011helper t u v (w:ws) | ws == [] = t*u*v*w | otherwise = yada nada mada -- What are yada nada mada? -- The 20x20 grid case will become: f0112D :: [[Int]] - Int -- where [[Int]] is a list of lists of rows, columns, major diagonals, minor diagonals. On Sun, Aug 28, 2011 at 5:10 AM, Oscar Picasso oscarpica...@gmail.com wrote: No. The answer I posted is not good. It worked, by chance, on a couple of small examples I tried but it could end up comparing sequence of 4 numbers that where not initially adjacent. On Sun, Aug 28, 2011 at 12:32 AM, Oscar Picasso oscarpica...@gmail.com wrote: Maybe this? f x@(a:b:c:d:[]) = x f (a:b:c:d:e:ys) = if e = a then f (b:c:d:e:ys) else f (a:b:c:d:ys) On Sat, Aug 27, 2011 at 8:26 PM, KC kc1...@gmail.com wrote: Think of the simplest version of the problem that isn't totally trivial. e.g. A one dimensional list of numbers. What would you do? Note: you only want to touch each element once. The 2 dimensional case could be handled by putting into lists: rows, columns, major diagonals, and minor diagonals. This isn't the fastest way of doing the problem but it has the advantage of avoiding indexitis. -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Project Euler: request for comments
I just noticed that the 20x20 grid has some 00 entries; thus, time could be saved by not touching any of the grid entries 3 cells away. Same for the 01 entries. The challenge, of course, is in finding these entries in the first place. :) On Sun, Aug 28, 2011 at 1:58 PM, KC kc1...@gmail.com wrote: Try something like the following: -- Project Euler 11 -- In the 20×20 grid below, four numbers along a diagonal line have been marked in red. -- snip -- The product of these numbers is 26 × 63 × 78 × 14 = 1788696. -- What is the greatest product of four adjacent numbers in any direction (up, down, left, right, or diagonally) in the 20×20 grid? import Data.List -- Doing the one dimensional case. f011 :: [Int] - Int f011 (t:u:v:xs) = f011helper t u v xs f011helper :: Int - Int - Int - [Int] - Int f011helper t u v (w:ws) | ws == [] = t*u*v*w | otherwise = yada nada mada -- What are yada nada mada? -- The 20x20 grid case will become: f0112D :: [[Int]] - Int -- where [[Int]] is a list of lists of rows, columns, major diagonals, minor diagonals. On Sun, Aug 28, 2011 at 5:10 AM, Oscar Picasso oscarpica...@gmail.com wrote: No. The answer I posted is not good. It worked, by chance, on a couple of small examples I tried but it could end up comparing sequence of 4 numbers that where not initially adjacent. On Sun, Aug 28, 2011 at 12:32 AM, Oscar Picasso oscarpica...@gmail.com wrote: Maybe this? f x@(a:b:c:d:[]) = x f (a:b:c:d:e:ys) = if e = a then f (b:c:d:e:ys) else f (a:b:c:d:ys) On Sat, Aug 27, 2011 at 8:26 PM, KC kc1...@gmail.com wrote: Think of the simplest version of the problem that isn't totally trivial. e.g. A one dimensional list of numbers. What would you do? Note: you only want to touch each element once. The 2 dimensional case could be handled by putting into lists: rows, columns, major diagonals, and minor diagonals. This isn't the fastest way of doing the problem but it has the advantage of avoiding indexitis. -- -- Regards, KC -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Project Euler: request for comments
Think of the simplest version of the problem that isn't totally trivial. e.g. A one dimensional list of numbers. What would you do? Note: you only want to touch each element once. The 2 dimensional case could be handled by putting into lists: rows, columns, major diagonals, and minor diagonals. This isn't the fastest way of doing the problem but it has the advantage of avoiding indexitis. On Fri, Aug 26, 2011 at 6:15 PM, Oscar Picasso oscarpica...@gmail.com wrote: Like: 20*19*21*18 is bigger than 100*100*3*2 ? If so I need to think about how to formalize it. Thanks for the hint. On Fri, Aug 26, 2011 at 8:55 PM, KC kc1...@gmail.com wrote: Is Problem 11 the 4 consecutive #'s problem? If so what must be true for 4 #'s to have a large product? Hint: x * y * z * 2 is that going to be larger? -- -- Regards, KC -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Project Euler: request for comments
Is Problem 11 the 4 consecutive #'s problem? If so what must be true for 4 #'s to have a large product? Hint: x * y * z * 2 is that going to be larger? -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] why the name lambda calculus?
See Serge Lang's Algebra. 2011/8/23 Rajesh S R srrajesh1...@gmail.com: Slight digression. Why not Lambda Algebra? In particular, what is the criteria for a system to be calculus and how's it different from algebra? -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] why the name lambda calculus?
Definition of calculus a : a method of computation or calculation in a special notation (as of logic or symbolic logic) b : the mathematical methods comprising differential and integral calculus —often used with the So a calculus means more than differentiation and integration it can also mean a system of symbols that can be mechanistically modified; algorithmically modified if you prefer. Lambda abstraction was probably chosen in case someone found better abstractions; e.g. epsilon, delta, gamma, beta, alpha, ... :) Or Joel Spolsky's leaky abstractions. :D On Sun, Aug 21, 2011 at 9:37 AM, C K Kashyap ckkash...@gmail.com wrote: Hi, Can someone please tell me what is the root of the name lambda calculus? Is it just because of the symbol lambda that is used? Why not alpha or beta calculus? Regards, Kashyap ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] why the name lambda calculus?
I had thyroid cancer a few years ago; now I've lost my sense of tumour. :) -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] [Haskell-beginners] Conciseness question
Sorry, I haven't read all the replies so I don't know if you have completely described the problem you're trying to solve; however, it might be better for people in future to say they want O(1) for insertions, O(lg n) for searching, etc. If they don't want to completely describe what their problem is. -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] For class Monoid; better names than mempty mappend might have been: mid (mident) mbinop
As pointed out earlier in this list, the name of the class and the methods are inconsistent. Monoid refers to a general algebraic structure, whereas mempty and mappend refer to certain instances like lists. Thank you for articulating what I was trying to get at. -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Is there a program to check if a matrix is totally unimodular?
-- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] A language that runs on the JVM or .NET has the advantage of Oracle Microsoft making those layers more parallelizable.
Are there plans a foot (or under fingers) to make a version of Haskell that runs on the JVM? -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] For class Monoid; better names than mempty mappend might have been: mid (mident) mbinop
I like the following but again + denotes addition and not a general binary operation. I personally often define the alias: (+) = mappend A lot of math books use + or x enclosed in a circle to indicate that the usual meaning of + nor x is intended for the meaning of the binary operation. I can't figure out if this would compile, the inside () representing a circle. ((+)) = mappend It would be easier for beginners to grok. I don't think so... but while we're at it, what's with that weird name Monoid anyway, let alone Functor, Monad, etc.? ;-) Ivan: I had thought those were words expressing valid mathematical concepts. In order to find similarities between apparently different operations data one wants to reason abstractly; similar to mathematics. -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] For class Monoid; better names than mempty mappend might have been: mid (mident) mbinop
It would be easier for beginners to grok. -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Call for GUI examples - Functional Reactive Programming
Can one do FRP with Haskell connected to Javascript in the browser? I believe there is a standalone version of Javascript. On 7/8/11, Heinrich Apfelmus apfel...@quantentunnel.de wrote: Chris Smith wrote: Heinrich Apfelmus wrote: Do you know any *small GUI programs* that you would *like* to see *implemented with Functional Reactive Programming?* This isn't really a specific application, but what I'd like to see most from FRP is an example of something that involves moving between windows and dialog boxes. All of the GUI-based FRP examples I've seen so far involve interactions in a specific GUI layout. It's unclear to me how FRP extends into a situation like: - There's a starting window showing several options for what to do - When the user chooses an option, that window closes, and a new one opens with that activity. - In response to some actions, dialog boxes appear with their own interactions. It's not clear to me if anyone in FRP has an idea of how stuff like this fits in. Is there some FRP trick to handle this declaratively? Or would you just say each move to a new window ends or pauses one network of events and behaviors, and starts a new one? That's a very good example. Unfortunately, I am one of those who don't have any idea of how stuff like this fits in. :) I think it's possible to get something like this with pausing and resuming event networks, but a general and elegant formulation would probably rely on dynamic event switching, which I haven't attempted to implement yet. I'm trying to pick the low hanging fruit first. Best regards, Heinrich Apfelmus -- http://apfelmus.nfshost.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Can one drop GHC 7.0.4 into the Haskell Platform or does the platform need to be updated?
-- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Haskell: The Craft of Functional Programming 3rd ed is out.
http://www.haskellcraft.com/craft3e/Home.html -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Dead else branch does influence runtime?
How is the compiler to know the else branch is never executed at run-time? If you do, then why is it there in your source code? On Tue, Jun 14, 2011 at 7:35 AM, Johannes Waldmann waldm...@imn.htwk-leipzig.de wrote: Thanks for the analysis. So is this a problem that should be fixed in GHC? And what can I do to circumvent the problem? (Perhaps write some RULES magic?) Thanks - J.W. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Dead else branch does influence runtime?
Superb; on how to avoid boxing. On Tue, Jun 14, 2011 at 7:51 AM, Daniel Fischer daniel.is.fisc...@googlemail.com wrote: On Tuesday 14 June 2011, 15:51:57, Daniel Fischer wrote: On Tuesday 14 June 2011, 14:35:19, Johannes Waldmann wrote: With id, main1 jumps to foldb_cap, which contains a lot of code for the (cap 1)-branch, and - that's what causes the slowdown - a worker loop $s$wfoldlM'_loop_s3EE [Occ=LoopBreaker] :: GHC.Prim.Int# - (GHC.Types.Int, GHC.Types.Int) - (# GHC.Types.Int, GHC.Types.Int #) which uses the passed functions (thus you have no inlining of eff and h1, and a boxed tuple of boxed Int's in your worker). I am sure GHC headquarters will look at this when they find the time but perhaps there's some additional knowledge on this mailing list that might help. Note that you get good behaviour when you help GHC a bit, in particular a static argument transformation for the function parameters of foldb_cap allows them to be inlined and (in this case) you get the nice loop on unboxed Int#s again: foldb_cap :: ( V.Unbox a, V.Unbox b ) = Int - b - ( a - b ) - ( b - b - b ) - Vector a - b foldb_cap cp strt f g xs = work cp strt xs where work cap e s = if cap = 1 then V.foldl' g e $ V.map f s -- replace id by undefined in the following, -- and notice a drastic decrease in runtime - -- although this branch is never executed: else id $ case V.length s of 0 - e 1 - f $! V.head s n - let splitAt k v = ( V.take k v, V.drop k v ) ( s1, s2 ) = splitAt ( div n 2 ) s cap' = div cap 2 v1 = work cap' e s1 v2 = work cap' e s2 v = g v1 v2 in par v1 $ pseq v2 $ v ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] In ML books; functors only consume produce structures; whereas, functions CP values.
I've never seen such an easy description in Haskell books. Is there more going on with Haskell functors? -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Can it be proven there are no intermediate useful type classes between Applicative Functors Monads?
On Mon, Jun 6, 2011 at 9:19 AM, Brent Yorgey byor...@seas.upenn.edu wrote: On Sun, Jun 05, 2011 at 12:51:47PM -0700, KC wrote: If new intermediate classes crop up then there would be no point in fixing class (Applicative m) = Monad m where since it would have to be changed if new intermediate classes are found. There actually is at least one intermediate class that I know of, class Applicative m = Branching m where branch :: m Bool - m a - m a - m a subject to the laws branch (m * pure True) t f == m * t branch (m * pure False) t f == m * f or something like that. The idea is that Applicative computations have a fixed structure which is independent of intermediate results; Monad computations correspond to (potentially) infinitely branching trees, since intermediate results (which could be of an infinite-sized type) can be used to compute the next action; but Branching computations correspond to *finitely* branching trees, since future computation can depend on intermediate results, but only one binary choice at a time. However, I doubt this qualifies as useful no matter how you define it, although I would not be sad to be proven wrong. In any case, I think it is ethically indefensible to procrastinate in doing something good just in case you might miss an opportunity to do something perfect later. -Brent I take it you would prefer the following signature class (Applicative m) = Monad m where -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Can it be proven there are no intermediate useful type classes between Applicative Functors Monads?
If new intermediate classes crop up then there would be no point in fixing class (Applicative m) = Monad m where since it would have to be changed if new intermediate classes are found. I realize non-existence proofs are hard. -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] I'm trying to install the Haskell Platform on a Mac and ...
I'm trying to install the Haskell Platform on a Mac and I've already installed Xcode 3.2.6 but the platform says that the tools are not installed. Do I need to reboot? -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] I'm trying to install the Haskell Platform on a Mac and ...
Never mind. I didn't realize there were two steps: - clicking on the dmg file - then actualling installing the software On Sun, Jun 5, 2011 at 1:20 PM, KC kc1...@gmail.com wrote: I'm trying to install the Haskell Platform on a Mac and I've already installed Xcode 3.2.6 but the platform says that the tools are not installed. Do I need to reboot? -- -- Regards, KC -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] OK! I have a Mac with Snow Leopard 10.6.7?, Xcode 3.2.6, Haskell Platform 2011.2.0.1; What are 2or 3 ways so far to get a GUI graphics?
-- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] The Lisp Curse
Librarians have been struggling for years with classifying topics; I don't imagine classifying coding libraries as any easier. :) -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Is there an efficient way to generate Euler's totient function for [2, 3..n]?
It's declarative and may help to verify more efficient implementations. WOW! Good insight. :) On Sun, May 22, 2011 at 9:27 AM, Henning Thielemann schlepp...@henning-thielemann.de wrote: Daniel Fischer schrieb: On Saturday 14 May 2011 19:38:03, KC wrote: Instead of finding the totient of one number, is there a quicker way when processing a sequence? For some sequences. You may find alternative ways of computation in the Online Encyclopedia of Integer Sequences. http://oeis.org/A10 -- From: http://www.haskell.org/haskellwiki/99_questions/Solutions/34 totient :: Int - Int totient n = length [x | x - [1..n], coprime x n] where coprime a b = gcd a b == 1 NEVER do that! It's awfully slow. It's declarative and may help to verify more efficient implementations. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Is there a place where we can have a discussion on the merits of various GUI's various graphics? And then vote?
:) -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Is there a place where we can have a discussion on the merits of various GUI's various graphics? And then vote?
So we can get this show on the road. Pun intended. :D On Fri, May 20, 2011 at 12:20 PM, KC kc1...@gmail.com wrote: :) -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] In several chapters there is a penetrating conceptual analysis of the matter at hand, on which a superstructure of code is erected.
Interesting comment on the book The Fun of Programming in JOOP. In several chapters there is a penetrating conceptual analysis of the matter at hand, on which a superstructure of code is erected. -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Extension for Pearls of Functional Algorithm Design by Richard Bird, 2010, page 25 #Haskell
Extension for Pearls of Functional Algorithm Design by Richard Bird, 2010, page 25 #Haskell --- --- module SelectionProblem where import Data.Array import Data.List --- --- -- Question: is there a way to get the type signature as the following: -- smallest :: (Ord a) = Int - [Array Int a] - a --- --- -- Works on 2 finite ordered disjoint sets represented as sorted arrays. smallest :: (Ord a) = Int - (Array Int a, Array Int a) - a smallest k (xa,ya) = search k (xa,ya) (0,m+1) (0,n+1) where (0,m) = bounds xa (0,n) = bounds ya -- Removed some of the indexitis at the cost of calling another function. search :: (Ord a) = Int - (Array Int a, Array Int a) - (Int,Int) - (Int,Int) - a search k (xa,ya) (lx,rx) (ly,ry) | lx == rx = ya ! (k+ly) | ly == ry = xa ! (k+lx) | otherwise = case (xa ! mx ya ! my) of (True)- smallest2h k (xa,ya) ((lx,mx,rx),(ly,my,ry)) (False) - smallest2h k (ya,xa) ((ly,my,ry),(lx,mx,rx)) where mx = (lx+rx) `div` 2 my = (ly+ry) `div` 2 -- Here the sorted arrays are in order by their middle elements. -- Only cutting the leading or trailing array by half. -- Here xa is the first array and ya the second array by their middle elements. smallest2h :: (Ord a) = Int - (Array Int a, Array Int a) - ((Int,Int,Int),(Int,Int,Int)) - a smallest2h k (xa,ya) ((lx,mx,rx),(ly,my,ry)) = case (k=mx-lx+my-ly) of (True)- search k (xa,ya) (lx,rx) (ly,my) (False) - search (k-(mx-lx)-1) (xa,ya) (mx+1,rx) (ly,ry) --- --- -- Works on 3 finite ordered disjoint sets represented as sorted arrays. smallest3 :: (Ord a) = Int - (Array Int a, Array Int a, Array Int a) - a smallest3 k (xa,ya,za) = -- On each recursive call the order of the arrays can switch. search3 k (xa,ya,za) (0,bx+1) (0,by+1) (0,bz+1) where (0,bx) = bounds xa (0,by) = bounds ya (0,bz) = bounds za -- Removed some of the indexitis at the cost of calling another function. search3 :: (Ord a) = Int - (Array Int a, Array Int a, Array Int a) - (Int,Int) - (Int,Int) - (Int,Int) - a search3 k (xa,ya,za) (lx,rx) (ly,ry) (lz,rz) | lx == rx ly == ry = za ! (k+lz) | ly == ry lz == rz = xa ! (k+lx) | lx == rx lz == rz = ya ! (k+ly) | lx == rx = search k (ya,za) (ly,ry) (lz,rz) | ly == ry = search k (xa,za) (lx,rx) (lz,rz) | lz == rz = search k (xa,ya) (lx,rx) (ly,ry) | otherwise = case (xa ! mx ya ! my, xa ! mx za ! mz, ya ! my za ! mz) of (True, True, True)- smallest3h k (xa,ya,za) ((lx,mx,rx),(ly,my,ry),(lz,mz,rz)) -- abc (True, True, False) - smallest3h k (xa,za,ya) ((lx,mx,rx),(lz,mz,rz),(ly,my,ry)) -- acb (False, True, True) - smallest3h k (ya,xa,za) ((ly,my,ry),(lx,mx,rx),(lz,mz,rz)) -- bac (False, False, True) - smallest3h k (ya,za,xa) ((ly,my,ry),(lz,mz,rz),(lx,mx,rx)) -- bca (True, False, False) - smallest3h k (za,xa,ya) ((lz,mz,rz),(lx,mx,rx),(ly,my,ry)) -- cab (False, False, False) - smallest3h k (za,ya,xa) ((lz,mz,rz),(ly,my,ry),(lx,mx,rx)) -- cba where mx = (lx+rx) `div` 2 my = (ly+ry) `div` 2 mz = (lz+rz) `div` 2 -- Here the sorted arrays are in order by their middle elements. -- Only cutting the leading or trailing array by half. -- Here xa is the first array, ya the second array, and za the third array by their middle elements. smallest3h :: (Ord a) = Int - (Array Int a, Array Int a, Array Int a) - ((Int,Int,Int),(Int,Int,Int),(Int,Int,Int)) - a smallest3h k (xa,ya,za) ((lx,mx,rx),(ly,my,ry),(lz,mz,rz)) = case (k=mx-lx+my-ly+mz-lz) of (True)- search3 k (xa,ya,za) (lx,rx) (ly,ry) (lz,mz) (False) - search3 (k-(mx-lx)-1) (xa,ya,za) (mx+1,rx) (ly,ry) (lz,rz) -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] For Euler 25; What is the first term in the Fibonacci sequence to contain 1000 digits?; the following seems to work.
For Euler 25; What is the first term in the Fibonacci sequence to contain 1000 digits?; the following seems to work. -- For number of digits being 5 or more. fibNdigits :: Int - Int fibNdigits nDigits = floor (((fromIntegral nDigits) - 1.0) / (logBase 10 phi)) + 2 where sq5 = sqrt 5 :: Double phi = (1 + sq5) / 2 -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Status of Haskell + Mac + GUIs graphics
Do GUIs or interactive graphics in Haskell work a lot better on Windows and/or various Linux distro's? On Tue, May 17, 2011 at 4:24 PM, Conal Elliott co...@conal.net wrote: I still haven't found any way to do GUIs or interactive graphics in Haskell on a Mac that isn't plagued one or more of the following serious problems: * Incompatible with ghci, e.g., fails to make a window frame or kills the process the second time one opens a top-level window, * Goes through the X server, and so doesn't look or act like a Mac app, * Doesn't support OpenGL. A year or two ago, I put my Haskell GUI graphics work on hold while waiting hoping for a functioning pathway to open. So far I haven't heard of one. If anyone has found a solution, I'd love to hear! - Conal ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- -- Regards, KC ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
