Re: [Haskell-cafe] Building all possible element combinations from N lists.
On Fri, Oct 26, 2012 at 2:34 AM, Jake McArthur jake.mcart...@gmail.comwrote: I golfed a bit. :) sequence = filterM (const [False ..]) What is golfed and = ? Please, explain. Thanks, Dmitri ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Building all possible element combinations from N lists.
Hi all,
I am looking for the algorithm and code better then the one I wrote (please
see below) to solve the problem given in the subject.
Unfortunately I finally need to implement this algorithm in Java. That's
why I am not only interested in beautiful Haskell algorithms, but also in
the one that I can without much pain implement in procedural PL like Java
:(
{--
Build all possible element combinations from N lists.
Valid combination consists of k = N elements.
Where each element of a single combination is taken from one of the N
lists.
When building combination any list can give only one element for this
combination.
In other words you can not take more then one element from one and the same
list when building current combination. Thus combinations between elements
from the same input list are not allowed.
Yet when building next combination you can use any of the lists again.
Order of elements in combinaton does not matter.
For example:
input = [
[[a],[b]],
[[1],[2]],
[[],[]]
]
output =
[
[a],[b],[1],[2],
[a,1],[a,2],[b,1],[b,2],
[],[],
[a,],[a,],[b,],[b,],
[1,],[1,],[2,],[2,],
[a,1,],[a,1,],[a,2,],[a,2,],
[b,1,],[b,1,],[b,2,],[b,2,]
]
(see bigger example at the end of the code)
Current implementation is based on the idea of using combinations
accumulator.
After first run accumulator contains:
1) All elements from the first two lists. These two lists are taken from
the input list of lists.
The elements of these first two lists are put in accumulator as is.
For example: [a],[b],[1],[2]
2) All combinations of these elements:
[a,1],[a,2],[b,1],[b,2]
Note: Combinations between elements from the same input list are not allowed
Next, on each run we add combinations built from accumulator elements
together with next list taken from the input list of list.
--}
input = [
[[a],[b]],
[[1],[2]],
[[],[]],
[[X],[Y]]
]
addAll :: [[[a]]] - [[a]]
addAll [] = []
addAll (x:[]) = x
addAll (x:y:[]) = accum x [y]
addAll inp = accum (initLst inp) (restLst inp)
initLst inp = fstLst ++ sndLst ++ (addLst fstLst sndLst) where
fstLst = inp !! 0
sndLst = inp !! 1
restLst inp = (tail . tail) inp
accum :: [[a]] - [[[a]]] - [[a]]
accum xs (r:rs) = accum (xs ++ r ++ addLst xs r) rs
accum xs _ = xs
addLst :: [[a]] - [[a]] - [[a]]
addLst (x:xs) ys = addOne x ys ++ addLst xs ys
addLst _ [] = []
addLst [] _ = []
addOne :: [a] - [[a]] - [[a]]
addOne x (y:ys) = [x ++ y] ++ addOne x ys
addOne x [] = []
{--
For example:
input = [
[[a],[b]],
[[1],[2]],
[[],[]],
[[X],[Y]]
]
output =
[
[],[],
[a],[b],[1],[2],
[a,1],[a,2],[b,1],[b,2],
[a,],[a,],[b,],[b,],
[1,],[1,],[2,],[2,],
[a,1,],[a,1,],[a,2,],[a,2,],
[b,1,],[b,1,],[b,2,],[b,2,],
[X],[Y],
[a,X],[a,Y],[b,X],[b,Y],
[1,X],[1,Y],[2,X],[2,Y],
[a,1,X],[a,1,Y],[a,2,X],[a,2,Y],
[b,1,X],[b,1,Y],[b,2,X],[b,2,Y],
[,X],[,Y],[,X],[,Y],
[a,,X],[a,,Y],[a,,X],[a,,Y],
[b,,X],[b,,Y],[b,,X],[b,,Y],
[1,,X],[1,,Y],[1,,X],[1,,Y],
[2,,X],[2,,Y],[2,,X],[2,,Y],
[a,1,,X],[a,1,,Y],[a,1,,X],[a,1,,Y],
[a,2,,X],[a,2,,Y],[a,2,,X],[a,2,,Y],
[b,1,,X],[b,1,,Y],[b,1,,X],[b,1,,Y],
[b,2,,X],[b,2,,Y],[b,2,,X],[b,2,,Y]
]
--}
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Re: [Haskell-cafe] Building all possible element combinations from N lists.
On Fri, Oct 26, 2012 Alex Stangl wrote: * * combos [] = [[]] combos ([]:ls) = combos ls combos ((h:t):ls) = map (h:) (combos ls) ++ combos (t:ls) Excellent, thanks! ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Debian 6.0.5: 'cabal install curl' problem
Please help to solve a problem installing curl package ( http://hackage.haskell.org/package/curl/) on Debian 6.0.5. I am running the most recent Debian Haskell platform with GHC 6.12.1. I did: - cabal update - cabal install cabal-install It is interesting that in case you do again 'cabal update you again get a suggestion from cabal to upgrade cabal-install, and this process never ends: - cabal update Downloading the latest package list from hackage.haskell.org Note: there is a new version of cabal-install available. To upgrade, run: cabal install cabal-install Anyway, then I did: - apt-get install curl - cabal install curl Cabal fails to install 'curl' because it can not find curl library. Please see detailed cabal output at the end of this message. So my questions: 1) What is missing to install curl package? 2) Should I upgrade Debian GHC 6.12.1 to the latest GHC 7.4.2? Maybe this should solve the problem with 'cabal install'? Thanks! -- cabal install output -- - cabal install curl Resolving dependencies... Configuring curl-1.3.7... checking for gcc... gcc checking for C compiler default output file name... a.out checking whether the C compiler works... yes checking whether we are cross compiling... no checking for suffix of executables... checking for suffix of object files... o checking whether we are using the GNU C compiler... yes checking whether gcc accepts -g... yes checking for gcc option to accept ANSI C... none needed checking how to run the C preprocessor... gcc -E configure: error: curl libraries not found, so curl package cannot be built See `config.log' for more details. cabal: Error: some packages failed to install: curl-1.3.7 failed during the configure step. The exception was: ExitFailure 1 ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Debian 6.0.5: 'cabal install curl' problem
Marcot, Thanks for the detailed info! Looks like aptitude install libcurl4-gnutls-dev solved the problem. cheers, Dmitri On Tue, Aug 14, 2012 at 6:29 PM, Marco Túlio Pimenta Gontijo marcotmar...@gmail.com wrote: Hi dokondr. On Tue, Aug 14, 2012 at 11:23 AM, dokondr doko...@gmail.com wrote: (...) Cabal fails to install 'curl' because it can not find curl library. Please see detailed cabal output at the end of this message. Cabal means the curl C library, which must be installed by either the packages libcurl4-openssl-dev or libcurl4-gnutls-dev. If a situation like this happens again, you can search for candidate packages with: $ apt-cache search lib curl dev collectd-core - statistics collection and monitoring daemon (core system) libcurl4-gnutls-dev - Development files and documentation for libcurl (GnuTLS) libcurl4-openssl-dev - Development files and documentation for libcurl (OpenSSL) devscripts - scripts to make the life of a Debian Package maintainer easier libflickcurl-dev - C library for accessing the Flickr API - development files libghc6-curl-dev - GHC 6 libraries for the libcurl Haskell bindings liblua5.1-curl-dev - libcURL development files for the Lua language version 5.1 liblua5.1-curl0 - libcURL bindings for the Lua language version 5.1 libwww-curl-perl - Perl bindings to libcurl libcurl-ocaml-dev - OCaml libcurl bindings (Development package) python-pycurl-dbg - Python bindings to libcurl (debug extension) python-pycurl - Python bindings to libcurl tclcurl - Tcl bindings to libcurl php5-curl - CURL module for php5 Or, even better, use the aptitude interface and search (with /) for lib curl dev, which will lead you directly to the right package in this case. Greetings. (...) -- marcot http://marcot.eti.br/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Simple GUI library to view JSON?
Please advise on a simple GUI library to display JSON data. A library that
is easy to build both on Win, Linux and OsX. I need a scrollable view to
show a list of JSON objects. Every object may contain other objects
(recursively). List may have thousands of objects. Fields may have very
long text values, so the view must also be scrollable in horizontal
dimension.
JSON object view should be click-able and look like on this example:
{
hey: guy,
anumber: 243,
- anobject: {
whoa: nuts,
- anarray: [
1,
2,
thrh1ee
],
more: stuff
},
awesome: true,
bogus: false,
meaning: null,
link: http://jsonview.com;,
}
Where '-' before the field object indicates that object was expanded and
'+' means collapsed object.
Clicking on expanded fields should collapse them and vice verse. So for
this example, clicking on 'anobject' should result in:
{
hey: guy,
anumber: 243,
anobject: {... }
awesome: true,
bogus: false,
meaning: null,
link: http://jsonview.com;,
}
In short I need a view similar to the one provided by JSONView plugin for
Firefox:
https://addons.mozilla.org/en-US/firefox/addon/jsonview/
Thanks a lot for any info, comments and ideas about this project!
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Re: [Haskell-cafe] Simple GUI library to view JSON?
Thanks, it is a good idea to use JSONView. Yet I also want to reuse this
code to view lists of objects in MongoDB collection. MongoDB objects are in
fact JSON, so the same code should work. I am not sure though that saving
MongoDB objects in intermediate JSON and then displaying them in JSONView
would be the best way to go.
On Mon, Feb 20, 2012 at 10:24 PM, Clark Gaebel
cgae...@csclub.uwaterloo.cawrote:
You could set up a simple web server (with, for example, Yesod [1])
serving up your JSON data, and then just connect to it with Firefox and use
JSONView.
[1] http://www.yesodweb.com/
On Mon, Feb 20, 2012 at 2:01 PM, dokondr doko...@gmail.com wrote:
Please advise on a simple GUI library to display JSON data. A library
that is easy to build both on Win, Linux and OsX. I need a scrollable view
to show a list of JSON objects. Every object may contain other objects
(recursively). List may have thousands of objects. Fields may have very
long text values, so the view must also be scrollable in horizontal
dimension.
JSON object view should be click-able and look like on this example:
{
hey: guy,
anumber: 243,
- anobject: {
whoa: nuts,
- anarray: [
1,
2,
thrh1ee
],
more: stuff
},
awesome: true,
bogus: false,
meaning: null,
link: http://jsonview.com;,
}
Where '-' before the field object indicates that object was expanded and
'+' means collapsed object.
Clicking on expanded fields should collapse them and vice verse. So for
this example, clicking on 'anobject' should result in:
{
hey: guy,
anumber: 243,
anobject: {... }
awesome: true,
bogus: false,
meaning: null,
link: http://jsonview.com;,
}
In short I need a view similar to the one provided by JSONView plugin for
Firefox:
https://addons.mozilla.org/en-US/firefox/addon/jsonview/
Thanks a lot for any info, comments and ideas about this project!
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[Haskell-cafe] ANN: NubFinder : Mining Opinions on the Web
Hello, I am pleased to announce NubFinder research project. Goal: develop technology to search and analyze user opinions on the Web. NubFinder and NubTrend are research prototypes trying first to accomplish a more 'simple' task - classification of emotions in Twitter messages, and then approach opinion mining. NubFinder project site: https://sites.google.com/site/nubfinder NubFinder discussion group: http://groups.google.com/group/nubfinder Thanks for your interest in NubFinder Research! -- All the best, Dmitri O. Kondratiev This is what keeps me going: discovery doko...@gmail.com http://sites.google.com/site/dokondr/welcome ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANN: NubFinder : Mining Opinions on the Web
On Thu, Feb 2, 2012 at 5:24 AM, Edward Amsden eca7...@cs.rit.edu wrote: Since this is an announcement on the Haskell mailing list, could you clarify the relevance to Haskell? It's not immediately obvious. Very true, sorry for missing this out. All server-side code including Twitter crawler and Sparse Vector Space Model classifier is written in Haskell http://www.haskell.org/ and compiled with The Glasgow Haskell Compiler http://www.haskell.org/ghc/. In case of interest in NubFinder project I will refactor the Haskell source into reusable library ready for Hackage. -- Edward Amsden On Wed, Feb 1, 2012 at 5:04 PM, dokondr doko...@gmail.com wrote: Hello, I am pleased to announce NubFinder research project. Goal: develop technology to search and analyze user opinions on the Web. NubFinder and NubTrend are research prototypes trying first to accomplish a more 'simple' task - classification of emotions in Twitter messages, and then approach opinion mining. NubFinder project site: https://sites.google.com/site/nubfinder NubFinder discussion group: http://groups.google.com/group/nubfinder Thanks for your interest in NubFinder Research! -- All the best, Dmitri O. Kondratiev This is what keeps me going: discovery doko...@gmail.com http://sites.google.com/site/dokondr/welcome ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Need advice: Haskell in Web Client
**Bardur Arantsson wrote: On 01/26/2012 11:16 AM, dokondr wrote: Ideally, I would be happy to be able to write in Haskell a complete front-end / GUI, so it could be compiled to different back-ends: Javascript to run in the Browser and also a standalone app. In Python world this is already done with Pyjamas (http://pyjs.org/) - a Rich Internet Application (RIA) Development Platform for both Web and Desktop. Also from Pyjamas site: Pyjamas ... contains a Python-to-Javascript compiler, an AJAX framework and a Widget Set API. Pyjamas Desktop is the Desktop version of Pyjamas Pyjamas Desktop allows the exact same python web application source code to be executed as a standalone desktop application (running under Python) instead of being stuck in a Web browser. Architecture diagram http://pyjs.org/wiki/pyjamasandpyjamasdesktop/ I wonder if somebody works on similar Haskell Rich Internet Application (RIA) Development Platform ? Any ideas, comments on implementation of such system in Haskell? What existing Haskell GUI libraries can be used for a desktop GUI, etc.? Well, it's basically just proof-of-concept at the moment, and it's not really usable for real applications at the moment, but there is http://hackage.haskell.org/package/dingo-core-0.1.0 http://hackage.haskell.org/package/dingo-widgets-0.1.0 http://hackage.haskell.org/package/dingo-example-0.1.0 The basic client-server communication, server-side state handling, etc. is there, but it's missing a couple of things before it could be used for real apps: There's no real security, and there are *very* few widgets. The few widgets that exist at the moment are also probably lacking a few operations. On the plus side, it's should be pretty easy to create new widgets. You can get a feel for how the thing looks from an application programmer's perspective by looking at the source for the example. Looks neat, thanks! If I got this write, in dingo all web page content is created by running Haskell on the server side in run-time and then sending generated html + js to the client (browser). I am looking for the opposite - when client does more work running Javascript generated by Haskell in advance, the approach that Pyjamas use ( http://pyjs.org/) with Python to Javascript compilation. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Need advice: Haskell in Web Client
On Thu, Jan 19, 2012 at 1:37 AM, Dag Odenhall dag.odenh...@gmail.comwrote: On Tue, 2012-01-17 at 22:05 +0300, dokondr wrote: I prefer using Turing complete PL to program web client, like the one used in GWT (Java) or Cappuccino (Objective-J). http://cappuccino.org/learn/ In this case you /almost/ don't need to know HTML, CSS, DOM, Ajax, etc. to develop WebUI and good PL lets you concentrate on problem domain instead of bothering about browser support. It is a real pity that Haskell still has no such tools to generate Web GUI in Javascript. ((( Have you seen Chris Done's posts on the subject? http://chrisdone.com/tags/javascript.html Thanks for the link! (Never seen this before) Ideally, I would be happy to be able to write in Haskell a complete front-end / GUI, so it could be compiled to different back-ends: Javascript to run in the Browser and also a standalone app. In Python world this is already done with Pyjamas (http://pyjs.org/) - a Rich Internet Application (RIA) Development Platform for both Web and Desktop. Also from Pyjamas site: Pyjamas ... contains a Python-to-Javascript compiler, an AJAX framework and a Widget Set API. Pyjamas Desktop is the Desktop version of Pyjamas Pyjamas Desktop allows the exact same python web application source code to be executed as a standalone desktop application (running under Python) instead of being stuck in a Web browser. Architecture diagram http://pyjs.org/wiki/pyjamasandpyjamasdesktop/ I wonder if somebody works on similar Haskell Rich Internet Application (RIA) Development Platform ? Any ideas, comments on implementation of such system in Haskell? What existing Haskell GUI libraries can be used for a desktop GUI, etc.? Thanks! ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Need advice: Haskell in Web Client
On Wed, Jan 18, 2012 at 10:47 AM, John Lenz l...@math.uic.edu wrote: I don't see a great need of developing something like GWT for haskell, since we already have good support for all sorts of existing tools that span more than just haskell, like extjs, yui, and jqueryui. Haskell makes my work doable in many areas where other PLs will take enormous efforts and time to achieve the same result. It would be great if I could write Web client code in pure Haskell (no HTML, no DOM, no Ajax, ..) compile it to Javascript and just run it in the browser and do all GUI and backend communication work. Simple as that. Regards, Dmitri. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Need advice: Haskell in Web Client
Hi all, I hope to use Haskell for graphics (charts) programming in Web client. My current implementation in brief: Server side, Haskell modules: 1) collecting various statistics from Twitter 2) generating text data for Gnuplot (http://www.gnuplot.info/) 3) Gnuplot creates png files with charts Web client: GWT (Google Web Toolkit) web UI that allows user to enter queries and see resulting charts in Web browser. Charts are png files generated by Gnuplot on the server side. Ideally, on the server side instead of using Gnuplot I would like Haskell to generate Javascript to be downloaded to Web client and draw charts in the browser. Something, very approximately, similar to what GWT does :) This code will be specific of course to plotting Javascript framework, no problem. Looking at Haskell in web browser - HaskellWiki: http://www.haskell.org/haskellwiki/Haskell_in_web_browser#Haskell_web_toolkit I feel a little confused about current state of the available Haskell tools for this task. Any ideas? Thanks! Dmitri ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Need advice: Haskell in Web Client
On Tue, Jan 17, 2012 at 6:42 PM, John Lenz l...@math.uic.edu wrote:
HTML5 Canvas is great for charts. If you go this route you might as well
use a library which draws charts for you instead of writing all this code
yourself.
Personally, I use extjs version 4 which has some amazing charts, but there
are other libraries out there.
http://www.sencha.com/**products/extjs/examples/#**sample-3http://www.sencha.com/products/extjs/examples/#sample-3
Essentially the server provides the data in JSON or XML some other format,
and the extjs code draws the charts on the client side.
If you go with extjs, then the server side I would suggest a small, simple
yesod or snap server. You could probably get the server under a hundred
lines of code with yesod; see some of the examples in the yesod book.
yesod or snap would serve JSON of the statistics on request, and also
serve the javascript files which draw the charts.
Yes, I was thinking about using Haskell to generate everything that
specific Javascript library needs to display charts in browser. Naturally
charts are to be displayed by this library itself. I also would like to
have Haskell tools to generate Web GUI in Javascript.
As for yesod, I am not sure that I like approach which mixes HTML with
code, or even worse - creates a new weird HTML-like language like 'whamlet
quasi-quotation', for example:
!-- a href=@{Page1R}Go to page 1! --
I prefer using Turing complete PL to program web client, like the one used
in GWT (Java) or Cappuccino (Objective-J). http://cappuccino.org/learn/
In this case you /almost/ don't need to know HTML, CSS, DOM, Ajax, etc. to
develop WebUI and good PL lets you concentrate on problem domain instead of
bothering about browser support.
It is a real pity that Haskell still has no such tools to generate Web GUI
in Javascript. (((
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[Haskell-cafe] Tracing Prelude.read exceptions
Hi, I got quite used to a sequence providing simple data persistence : 1) Store my data to a file: writeFile fileName (show someData) 2) Some time later read this data back: line - readFile fileName let someData = read line :: SomeDataType Having this done hundreds of times I now got stuck with step 2) trying to read moderately complex structure back. I get read exception in run-time: fromList *** Exception: Prelude.read: no parse I have checked and rechecked my types, data files, etc. - and still no idea. So my question: Is there any way to trace Prelude.read exceptions to see exactly on what data element read fails in run-time? Thanks! ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] No instance for (Read POSIXTime)
Yitz, thanks for the detailed answer! May be I should have formulated my question differently. All I actually need is some way to get *seconds* since epoch from the system, so I could manipulate them as integers. Correct me if I am wrong, but UTCTime does not help here. The only way I found to get seconds form epoch using existing today GHC libraries is that: utcStr = Wed, 07 Dec 2011 10:10:05 + posixSecondsIntg = read posixSecondsStr :: Integer posixSecondsStr = init $ show (cvtUTCtoSec utcStr) -- throw away 's' from posix seconds string, s\ uch as 1235657s cvtUTCtoSec utcTimeStr = utcTimeToPOSIXSeconds utcTime where utcTime = fromJust $ tryParseTime utcTimeStr timeFormat1 = %a, %d %b %Y %T %z timeFormat2 = %m/%e/%Y %l:%M:%S %p tryParseTime :: String - Maybe UTCTime tryParseTime timeStr = tryFormat (parseTime defaultTimeLocale timeFormat1 timeStr :: Maybe UTCTime) where tryFormat time | time == Nothing = parseTime defaultTimeLocale timeFormat2 timeStr :: Maybe UTCTime | otherwise = time Not a very easy way, isn't it? On Sun, Dec 11, 2011 at 9:22 PM, Yitzchak Gale g...@sefer.org wrote: dokondr wrote: When I try to read POSIXTime... No instance for (Read POSIXTime)... What should I do to provide Read instance for POSIXTime? Short answer: if you are thinking about this as a moment in time that could be parsed from the usual kind of string representation for that, you probably want to use UTCTime in your data type, not POSIXTime. If you really, really want to represent it internally as POSIXTime, then you should read those strings as UTCTime and then convert them to POSIXTime to store in your data type. I.e., in that case don't make your data type an instance of Read. POSIXTime is just a type alias for NominalDiffTime, i.e., a quantity of time between two moments. This is what the Show instance looks like: Prelude Data.Time realToFrac 100 :: NominalDiffTime 100s By convention, the Read instance would expect a string in that format. Generally people aren't interested in that, so there is no Read instance. Even if you did want to parse that, you would just parse it as a number and then use realToFrac, as I did above. The rule of thumb is: always represent moments in time as a UTCTime. Regards, Yitz ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] No instance for (Read POSIXTime)
Hi,
I need to read / write epoch seconds from / to plain text files.
When I try to read POSIXTime that I use in my own data type:
data TimedClassRecT = TCR {timeStamp :: POSIXTime, classCosMap :: Map.Map
String Float}
deriving (Eq, Read, Show)
I get the following error:
No instance for (Read POSIXTime)
arising from the 'deriving' clause of a data type declaration
Possible fix:
add an instance declaration for (Read POSIXTime)
or use a standalone 'deriving instance' declaration,
so you can specify the instance context yourself
When deriving the instance for (Read TimedClassRecT)
What should I do to provide Read instance for POSIXTime? I would rather not
implement it myself.
Thanks!
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[Haskell-cafe] Converting string to System.Time.ClockTime
Hi, What would be the simplest way to convert strings like Wed, 07 Dec 2011 10:09:21 + to System.Time.ClockTime ? Thanks! ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Converting string to System.Time.ClockTime
I need to parse time strings like Wed, 07 Dec 2011 10:09:21 + to a type that: 1) implements Eq, Ord 2) is numerical, so I could subtract one value from another to find the difference or interval length To answer 1) requirement I wrote the following snippet. Yet I could not subtract UTCTime values. How can I convert them to milliseconds? import Data.Time.Format import Data.Time.Clock import Locale import Data.Maybe s1 = Wed, 07 Dec 2011 10:09:21 + s2 = Wed, 07 Dec 2011 10:11:00 + t1 = fromJust $ tryParseTime s1 t2 = fromJust $ tryParseTime s2 t = compare t1 t2 tryParseTime :: String - Maybe UTCTime tryParseTime timeStr = tryFormat (parseTime defaultTimeLocale timeFormat1 timeStr :: Maybe UTCTime) where tryFormat time | time == Nothing = parseTime defaultTimeLocale timeFormat2 timeStr :: Maybe UTCTime | otherwise = time timeFormat1 = %a, %d %b %Y %T %z timeFormat2 = %m/%e/%Y %l:%M:%S %p On Thu, Dec 8, 2011 at 6:12 PM, Erik Hesselink hessel...@gmail.com wrote: I'm not sure if you really need ClockTime (from old-time), but if you don't, the types from the 'time' package are all parseable with `parseTime` [1]. Erik [1] http://hackage.haskell.org/packages/archive/time/latest/doc/html/Data-Time-Format.html#v:parseTime On Thu, Dec 8, 2011 at 14:16, dokondr doko...@gmail.com wrote: Hi, What would be the simplest way to convert strings like Wed, 07 Dec 2011 10:09:21 + to System.Time.ClockTime ? Thanks! ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Converting string to System.Time.ClockTime
Now, when I have managed to convert UTCTime to seconds (see code below) I got stuck trying to convert from UTCTime to CalendarTime, how to do this? import Data.Time.Format import Data.Time.Clock import Locale import Data.Maybe import Data.Time.Clock.POSIX s1 = Wed, 07 Dec 2011 10:09:21 + s2 = Wed, 07 Dec 2011 10:11:00 + t1 = fromJust $ tryParseTime s1 t2 = fromJust $ tryParseTime s2 pt1 = utcTimeToPOSIXSeconds t1 -- :: UTCTime - POSIXTime pt2 = utcTimeToPOSIXSeconds t2 pt3 = pt1 + (pt2 - pt1) / 2 t3 = posixSecondsToUTCTime pt3 t = compare t1 t2 tryParseTime :: String - Maybe UTCTime tryParseTime timeStr = tryFormat (parseTime defaultTimeLocale timeFormat1 timeStr :: Maybe UTCTime) where tryFormat time | time == Nothing = parseTime defaultTimeLocale timeFormat2 timeStr :: Maybe UTCTime | otherwise = time timeFormat1 = %a, %d %b %Y %T %z timeFormat2 = %m/%e/%Y %l:%M:%S %p -- timeFormat1 = %m/%d/%Y %l:%M:%S %p On Thu, Dec 8, 2011 at 6:30 PM, dokondr doko...@gmail.com wrote: I need to parse time strings like Wed, 07 Dec 2011 10:09:21 + to a type that: 1) implements Eq, Ord 2) is numerical, so I could subtract one value from another to find the difference or interval length To answer 1) requirement I wrote the following snippet. Yet I could not subtract UTCTime values. How can I convert them to milliseconds? import Data.Time.Format import Data.Time.Clock import Locale import Data.Maybe s1 = Wed, 07 Dec 2011 10:09:21 + s2 = Wed, 07 Dec 2011 10:11:00 + t1 = fromJust $ tryParseTime s1 t2 = fromJust $ tryParseTime s2 t = compare t1 t2 tryParseTime :: String - Maybe UTCTime tryParseTime timeStr = tryFormat (parseTime defaultTimeLocale timeFormat1 timeStr :: Maybe UTCTime) where tryFormat time | time == Nothing = parseTime defaultTimeLocale timeFormat2 timeStr :: Maybe UTCTime | otherwise = time timeFormat1 = %a, %d %b %Y %T %z timeFormat2 = %m/%e/%Y %l:%M:%S %p On Thu, Dec 8, 2011 at 6:12 PM, Erik Hesselink hessel...@gmail.comwrote: I'm not sure if you really need ClockTime (from old-time), but if you don't, the types from the 'time' package are all parseable with `parseTime` [1]. Erik [1] http://hackage.haskell.org/packages/archive/time/latest/doc/html/Data-Time-Format.html#v:parseTime On Thu, Dec 8, 2011 at 14:16, dokondr doko...@gmail.com wrote: Hi, What would be the simplest way to convert strings like Wed, 07 Dec 2011 10:09:21 + to System.Time.ClockTime ? Thanks! ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Converting string to System.Time.ClockTime
Ok, maybe you could advise what packages to use for this simple scenario: I have two text strings with dates: s1 = Wed, 07 Dec 2011 10:09:21 + s2 = Wed, 07 Dec 2011 10:11:00 + I need: 1) Find how many seconds are between these dates 2) Calculate the date in the middle between these dates 3) Print out all three dates in the different format, like these: 2011, 7 Dec, Wed, 10:11:00 What functions should I use to implement this? On Thu, Dec 8, 2011 at 7:13 PM, Antoine Latter aslat...@gmail.com wrote: On Thu, Dec 8, 2011 at 9:01 AM, dokondr doko...@gmail.com wrote: Now, when I have managed to convert UTCTime to seconds (see code below) I got stuck trying to convert from UTCTime to CalendarTime, how to do this? It might be easier to use 'diffUTCTime' and 'addUTCTime' instead of converting to and from POSIX seconds. What do you need the 'CalendarTime' for? I recommend not mixing the 'time' and 'old-time' packages if you can avoid it. If you really need to for inter-operating with some other library, it looks like you can use the 'datetime' package to convert from a UTCTime to a ClockTime, and then you can use the 'old-time' package to convert from a 'ClockTime' to a 'CalendarTime'. Antoine import Data.Time.Format import Data.Time.Clock import Locale import Data.Maybe import Data.Time.Clock.POSIX s1 = Wed, 07 Dec 2011 10:09:21 + s2 = Wed, 07 Dec 2011 10:11:00 + t1 = fromJust $ tryParseTime s1 t2 = fromJust $ tryParseTime s2 pt1 = utcTimeToPOSIXSeconds t1 -- :: UTCTime - POSIXTime pt2 = utcTimeToPOSIXSeconds t2 pt3 = pt1 + (pt2 - pt1) / 2 t3 = posixSecondsToUTCTime pt3 t = compare t1 t2 tryParseTime :: String - Maybe UTCTime tryParseTime timeStr = tryFormat (parseTime defaultTimeLocale timeFormat1 timeStr :: Maybe UTCTime) where tryFormat time | time == Nothing = parseTime defaultTimeLocale timeFormat2 timeStr :: Maybe UTCTime | otherwise = time timeFormat1 = %a, %d %b %Y %T %z timeFormat2 = %m/%e/%Y %l:%M:%S %p -- timeFormat1 = %m/%d/%Y %l:%M:%S %p On Thu, Dec 8, 2011 at 6:30 PM, dokondr doko...@gmail.com wrote: I need to parse time strings like Wed, 07 Dec 2011 10:09:21 + to a type that: 1) implements Eq, Ord 2) is numerical, so I could subtract one value from another to find the difference or interval length To answer 1) requirement I wrote the following snippet. Yet I could not subtract UTCTime values. How can I convert them to milliseconds? import Data.Time.Format import Data.Time.Clock import Locale import Data.Maybe s1 = Wed, 07 Dec 2011 10:09:21 + s2 = Wed, 07 Dec 2011 10:11:00 + t1 = fromJust $ tryParseTime s1 t2 = fromJust $ tryParseTime s2 t = compare t1 t2 tryParseTime :: String - Maybe UTCTime tryParseTime timeStr = tryFormat (parseTime defaultTimeLocale timeFormat1 timeStr :: Maybe UTCTime) where tryFormat time | time == Nothing = parseTime defaultTimeLocale timeFormat2 timeStr :: Maybe UTCTime | otherwise = time timeFormat1 = %a, %d %b %Y %T %z timeFormat2 = %m/%e/%Y %l:%M:%S %p On Thu, Dec 8, 2011 at 6:12 PM, Erik Hesselink hessel...@gmail.com wrote: I'm not sure if you really need ClockTime (from old-time), but if you don't, the types from the 'time' package are all parseable with `parseTime` [1]. Erik [1] http://hackage.haskell.org/packages/archive/time/latest/doc/html/Data-Time-Format.html#v:parseTime On Thu, Dec 8, 2011 at 14:16, dokondr doko...@gmail.com wrote: Hi, What would be the simplest way to convert strings like Wed, 07 Dec 2011 10:09:21 + to System.Time.ClockTime ? Thanks! ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Converting string to System.Time.ClockTime
On Thu, Dec 8, 2011 at 7:39 PM, Antoine Latter aslat...@gmail.com wrote: On Thu, Dec 8, 2011 at 9:30 AM, dokondr doko...@gmail.com wrote: Ok, maybe you could advise what packages to use for this simple scenario: I have two text strings with dates: s1 = Wed, 07 Dec 2011 10:09:21 + s2 = Wed, 07 Dec 2011 10:11:00 + I need: 1) Find how many seconds are between these dates 2) Calculate the date in the middle between these dates It looks like you already have 1) and 2) finished, using the 'time' package. 3) Print out all three dates in the different format, like these: 2011, 7 Dec, Wed, 10:11:00 If you need to convert into a specific time-zone you can use the 'utcToLocalTime' function in the 'time' package, which takes a UTCTime and a TimeZone to create a 'LocalTime'. I'm just guessing that you might want this, as your output format doesn't include time-zone information. Then for formatting, the 'Data.Time.Format' module in the 'time' package has the function 'formatTime', which uses the same sort of format string used by 'parseTime'. I hope that helps! It took me a while to find my way around the 'time' package properly. Antoine Thanks so much for your help! I think I finally :) solved this problem: import Data.Time.Format import Data.Time.Clock import Locale import Data.Maybe import Data.Time.Clock.POSIX timeFormat1 = %a, %d %b %Y %T %z timeFormat2 = %m/%e/%Y %l:%M:%S %p s1 = Wed, 07 Dec 2011 10:09:21 + s2 = Wed, 07 Dec 2011 10:11:00 + t1 = fromJust $ tryParseTime s1 -- :: UTCTime t2 = fromJust $ tryParseTime s2 pt1 = utcTimeToPOSIXSeconds t1 -- :: POSIXTime pt2 = utcTimeToPOSIXSeconds t2 pt3 = pt1 + (pt2 - pt1) / 2 t3 = posixSecondsToUTCTime pt3 -- :: UTCTime -- formatTime :: FormatTime t = TimeLocale - String - t - String s3 = formatTime defaultTimeLocale timeFormat2 t3 test = (compare t1 t2) == (compare pt1 pt2) tryParseTime :: String - Maybe UTCTime tryParseTime timeStr = tryFormat (parseTime defaultTimeLocale timeFormat1 timeStr :: Maybe UTCTime) where tryFormat time | time == Nothing = parseTime defaultTimeLocale timeFormat2 timeStr :: Maybe UTCTime | otherwise = time ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Where threadSleep is defined?
Hi, I need to make the current process (executing thread) go to sleep for a given amount of time. Can't find where threadSleep is defined. Thanks! ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Where threadSleep is defined?
I was trying to google haskell process sleep without much success. It really needs some experience to construct hoogle queries correctly :) Thanks everybody for your help! On Tue, Dec 6, 2011 at 8:07 PM, Paul R paul.r...@gmail.com wrote: dokondr Hi, I need to make the current process (executing thread) go to dokondr sleep for a given amount of time. Can't find where threadSleep dokondr is defined. Maybe because there is no such threadSleep function in base packages, what do you think ? Ok, let's see if we can find what you are looking for ... You want a function that will pause your thread for an amout of time then pass. In other word, it would take an Int and do nothing else than wait as a side effect, right ? Something typed Int - IO () should do that, right ? http://www.haskell.org/hoogle/?hoogle=Int+-%3E+IO+%28%29 = threadDelay :: Int - IO () Suspends the current thread for a given number of microseconds ... And if you don't want to use the amazing power of hoogle, maybe you can simply go to your favorite search engine and type haskell pause thread in it. In mine, the first result is the doc of the Control.Concurrent module that has a Waiting section (linked in the toc) that has ... 3 functions, amongst wich threadDelay :: Int - IO (). Wasn't hard, was it ? -- Paul ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] How to get a file path to the program invoked?
This is how I finally solved this problem for POSIX complaint system:
--
-- TestRun
--
module Main where
import System.Cmd (rawSystem)
import System.Directory (getCurrentDirectory)
import System.Environment.Executable (ScriptPath(..), getScriptPath)
import System.FilePath.Posix (splitFileName)
main = do
path - getMyPath
putStrLn $ myPath = ++ path
let cmdLine = path ++ args.sh
rawSystem cmdLine [iphone, test-twitts.txt]
{--
data ScriptPath Source
Constructors:
Executable FilePathit was (probably) a proper compiled executable
RunGHC FilePathit was a script run by runghc/runhaskell
Interactive we are in GHCi
--}
getMyPath = do
curDir - getCurrentDirectory -- from System.Directory
scriptPath - getScriptPath -- from System.Environment.Executable
let path = getMyPath' scriptPath curDir
return path
getMyPath' (Executable path) _ = fst (splitFileName path)
getMyPath' (RunGHC path) _ = fst (splitFileName path)
getMyPath' Interactive curDir = curDir++/
--
All the best,
Dmitri O. Kondratiev
This is what keeps me going: discovery
doko...@gmail.com
http://sites.google.com/site/dokondr/welcome
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Re: [Haskell-cafe] writeFile: commitBuffer: invalid argument (Illegal byte sequence)
I don't actually need UTF-16 code in these strings. I would rather filter them out before writing such strings to a file. What would be a simple filter to do this? *Albert Y. C. Lai* trebla at vex.net haskell-cafe%40haskell.org?Subject=Re%3A%20%5BHaskell-cafe%5D%20writeFile%3A%20commitBuffer%3A%20invalid%20argument%0A%20%28Illegal%20byte%20sequence%29In-Reply-To=%3C4EDBBEB6.3050201%40vex.net%3E wrote: On 11-12-04 07:08 AM, dokondr wrote: * In GHC 7.0.3 / Mac OS X when trying to: ** ** writeFile someFile (Hoping You Have A iPhone When I Do This) Lol ** Sleep Is When You Close These ---gt; \55357\56384 ** ** I get: * * commitBuffer: invalid argument (Illegal byte sequence) ** ** The string I am trying to write can also be seen here: ** http://twitter.com/#!/search/Hoping%20You%20Have%20A%20iPhone%20When%20I%20Do%20This%20lang%3Aenhttp://twitter.com/#%21/search/Hoping%20You%20Have%20A%20iPhone%20When%20I%20Do%20This%20lang%3Aen ** http://twitter.com/#%21/search/Hoping%20You%20Have%20A%20iPhone%20When%20I%20Do%20This%20lang%3Aen * \55357 and \56384 would be surrogates D83D and DC40 for use in UTF-16 only. Haskell's Char is not a UTF-16 code unit (unlike early versions of Java and probably current ones). GHC is correct in rejecting them. Haskell's Char is a Unicode character directly. If you want the character U+1F440 EYES, write \128064 directly (or \x1f440, or \x1F440). Use http://www.unicode.org/charts/ to find out what you are getting into. You can enter a hexadecimal number or choose a category. On Sun, Dec 4, 2011 at 11:43 PM, Erik Hesselink hessel...@gmail.com wrote: Yes, you can set the text encoding on the handle you're reading this text from [1]. The default text encoding is determined by the environment, which is why I asked about LANG. If you're entering literal strings, see Albert Lai's answer. Erik [1] http://hackage.haskell.org/packages/archive/base/latest/doc/html/System-IO.html#g:23 On Sun, Dec 4, 2011 at 19:13, dokondr doko...@gmail.com wrote: Is there any other way to solve this problem without changing LANG environment variable? On Sun, Dec 4, 2011 at 8:27 PM, Erik Hesselink hessel...@gmail.com wrote: What is the value of your LANG environment variable? Does it still give the error if you set it to e.g. en_US.UTF-8? Erik On Sun, Dec 4, 2011 at 13:12, dokondr doko...@gmail.com wrote: Correct url of a bad string: http://twitter.com/#!/search/Hoping%20You%20Have%20A%20iPhone%20When%20I%20Do%20This%20lang%3Aenhttp://twitter.com/#%21/search/Hoping%20You%20Have%20A%20iPhone%20When%20I%20Do%20This%20lang%3Aen On Sun, Dec 4, 2011 at 3:08 PM, dokondr doko...@gmail.com wrote: Hi, In GHC 7.0.3 / Mac OS X when trying to: writeFile someFile (Hoping You Have A iPhone When I Do This) Lol Sleep Is When You Close These ---gt; \55357\56384 I get: commitBuffer: invalid argument (Illegal byte sequence) The string I am trying to write can also be seen here: http://twitter.com/#!/search/Hoping%20You%20Have%20A%20iPhone%20When%20I%20Do%20This%20lang%3Aenhttp://twitter.com/#%21/search/Hoping%20You%20Have%20A%20iPhone%20When%20I%20Do%20This%20lang%3Aen It looks like 'writeFile' can not write unicode characters. Any workarounds? Thanks! Dmitri ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] How to get a file path to the program invoked?
Balazs, thanks for your comments!
The first comment works just fine.
With / operator I get this:
Main System.Environment.Executable System.FilePath /abc / /
/
Instead of getting /abc/ I get /. What am I doing wrong?
On Mon, Dec 5, 2011 at 6:03 PM, Balazs Komuves bkomu...@gmail.com wrote:
Two small comments:
1) This should work on Windows too, if you just leave out the word Posix
from the source:
import System.FilePath (splitFileName)
2) In general when dealing with paths, use the / operator (from
System.FilePath)
instead of ++ / ++
Balazs
On Mon, Dec 5, 2011 at 1:44 PM, dokondr doko...@gmail.com wrote:
This is how I finally solved this problem for POSIX complaint system:
--
-- TestRun
--
module Main where
import System.Cmd (rawSystem)
import System.Directory (getCurrentDirectory)
import System.Environment.Executable (ScriptPath(..), getScriptPath)
import System.FilePath.Posix (splitFileName)
main = do
path - getMyPath
putStrLn $ myPath = ++ path
let cmdLine = path ++ args.sh
rawSystem cmdLine [iphone, test-twitts.txt]
{--
data ScriptPath Source
Constructors:
Executable FilePathit was (probably) a proper compiled executable
RunGHC FilePathit was a script run by runghc/runhaskell
Interactive we are in GHCi
--}
getMyPath = do
curDir - getCurrentDirectory -- from System.Directory
scriptPath - getScriptPath -- from System.Environment.Executable
let path = getMyPath' scriptPath curDir
return path
getMyPath' (Executable path) _ = fst (splitFileName path)
getMyPath' (RunGHC path) _ = fst (splitFileName path)
getMyPath' Interactive curDir = curDir++/
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Re: [Haskell-cafe] How to get a file path to the program invoked?
Thanks,
'addTrailingPathSeparator' works just fine !
On Mon, Dec 5, 2011 at 7:52 PM, Erik Hesselink hessel...@gmail.com wrote:
The operator / is an alias for `combine`, which the documentation says:
Combine two paths, if the second path isAbsolute, then it returns the
second.
In this case, / is absolute, so it is returned.
If you wish to add a trailing path separator, use
`addTrailingPathSeparator`.
Erik
On Mon, Dec 5, 2011 at 15:53, dokondr doko...@gmail.com wrote:
Balazs, thanks for your comments!
The first comment works just fine.
With / operator I get this:
Main System.Environment.Executable System.FilePath /abc / /
/
Instead of getting /abc/ I get /. What am I doing wrong?
On Mon, Dec 5, 2011 at 6:03 PM, Balazs Komuves bkomu...@gmail.com
wrote:
Two small comments:
1) This should work on Windows too, if you just leave out the word
Posix
from the source:
import System.FilePath (splitFileName)
2) In general when dealing with paths, use the / operator (from
System.FilePath)
instead of ++ / ++
Balazs
On Mon, Dec 5, 2011 at 1:44 PM, dokondr doko...@gmail.com wrote:
This is how I finally solved this problem for POSIX complaint system:
--
-- TestRun
--
module Main where
import System.Cmd (rawSystem)
import System.Directory (getCurrentDirectory)
import System.Environment.Executable (ScriptPath(..), getScriptPath)
import System.FilePath.Posix (splitFileName)
main = do
path - getMyPath
putStrLn $ myPath = ++ path
let cmdLine = path ++ args.sh
rawSystem cmdLine [iphone, test-twitts.txt]
{--
data ScriptPath Source
Constructors:
Executable FilePathit was (probably) a proper compiled executable
RunGHC FilePathit was a script run by runghc/runhaskell
Interactive we are in GHCi
--}
getMyPath = do
curDir - getCurrentDirectory -- from System.Directory
scriptPath - getScriptPath -- from System.Environment.Executable
let path = getMyPath' scriptPath curDir
return path
getMyPath' (Executable path) _ = fst (splitFileName path)
getMyPath' (RunGHC path) _ = fst (splitFileName path)
getMyPath' Interactive curDir = curDir++/
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[Haskell-cafe] writeFile: commitBuffer: invalid argument (Illegal byte sequence)
Hi, In GHC 7.0.3 / Mac OS X when trying to: writeFile someFile (Hoping You Have A iPhone When I Do This) Lol Sleep Is When You Close These ---gt; \55357\56384 I get: commitBuffer: invalid argument (Illegal byte sequence) The string I am trying to write can also be seen here: http://twitter.com/#!/search/Hoping%20You%20Have%20A%20iPhone%20When%20I%20Do%20This%20lang%3Aenhttp://twitter.com/#%21/search/Hoping%20You%20Have%20A%20iPhone%20When%20I%20Do%20This%20lang%3Aen It looks like 'writeFile' can not write unicode characters. Any workarounds? Thanks! Dmitri ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] writeFile: commitBuffer: invalid argument (Illegal byte sequence)
Correct url of a bad string: http://twitter.com/#!/search/Hoping%20You%20Have%20A%20iPhone%20When%20I%20Do%20This%20lang%3Aen On Sun, Dec 4, 2011 at 3:08 PM, dokondr doko...@gmail.com wrote: Hi, In GHC 7.0.3 / Mac OS X when trying to: writeFile someFile (Hoping You Have A iPhone When I Do This) Lol Sleep Is When You Close These ---gt; \55357\56384 I get: commitBuffer: invalid argument (Illegal byte sequence) The string I am trying to write can also be seen here: http://twitter.com/#!/search/Hoping%20You%20Have%20A%20iPhone%20When%20I%20Do%20This%20lang%3Aenhttp://twitter.com/#%21/search/Hoping%20You%20Have%20A%20iPhone%20When%20I%20Do%20This%20lang%3Aen It looks like 'writeFile' can not write unicode characters. Any workarounds? Thanks! Dmitri ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] writeFile: commitBuffer: invalid argument (Illegal byte sequence)
Is there any other way to solve this problem without changing LANG environment variable? On Sun, Dec 4, 2011 at 8:27 PM, Erik Hesselink hessel...@gmail.com wrote: What is the value of your LANG environment variable? Does it still give the error if you set it to e.g. en_US.UTF-8? Erik On Sun, Dec 4, 2011 at 13:12, dokondr doko...@gmail.com wrote: Correct url of a bad string: http://twitter.com/#!/search/Hoping%20You%20Have%20A%20iPhone%20When%20I%20Do%20This%20lang%3Aenhttp://twitter.com/#%21/search/Hoping%20You%20Have%20A%20iPhone%20When%20I%20Do%20This%20lang%3Aen On Sun, Dec 4, 2011 at 3:08 PM, dokondr doko...@gmail.com wrote: Hi, In GHC 7.0.3 / Mac OS X when trying to: writeFile someFile (Hoping You Have A iPhone When I Do This) Lol Sleep Is When You Close These ---gt; \55357\56384 I get: commitBuffer: invalid argument (Illegal byte sequence) The string I am trying to write can also be seen here: http://twitter.com/#!/search/Hoping%20You%20Have%20A%20iPhone%20When%20I%20Do%20This%20lang%3Aenhttp://twitter.com/#%21/search/Hoping%20You%20Have%20A%20iPhone%20When%20I%20Do%20This%20lang%3Aen It looks like 'writeFile' can not write unicode characters. Any workarounds? Thanks! Dmitri ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] How to get a file path to the program invoked?
Hi, When my program starts it needs to know a complete path to the directory from which it was invoked. In terms of standard shell (sh) I need the Haskell function that will do equivalent to: #!/bin/sh path=$(dirname $0) How to get this path in Haskell? getProgName :: IO String defined System.Environment only returns a file name of the program without its full path. Thanks! ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] How to get a file path to the program invoked?
System.Directory.getCurrentDirectory does not solve the problem.
System.Directory.getCurrentDirectory returns the directory *from which* the
program was called, also called working directory.
The directory *from which* the program was called is not the same that the
directory *where the program executable is*, which my program needs to know.
For example:
/opt/myApp/test/myProg - is a program
One may call it in many ways:
1)
cd /opt/myApp/test/
./myProg
Current or working directory: ./
or:
2)
cd /usr/local
/opt/myApp/test/myProg
Current or working directory: /usr/local
On the contrary, standard shell variable $0 - contains a full path to the
program location in the directory structure, no matter from what directory
the program was called.
How to find this path using GHC libraries?
On Thu, Dec 1, 2011 at 8:53 PM, Felipe Almeida Lessa felipe.le...@gmail.com
wrote:
Neither does $0, does it? It depends on how the program is called.
You can always use System.Directory.getCurrentDirectory with
System.FilePath.{isRelative,replaceDirectory} if you somehow need the
full path. Note, however, that not even this is generally guaranteed
to be correct.
Cheers,
--
Felipe.
--
All the best,
Dmitri O. Kondratiev
This is what keeps me going: discovery
doko...@gmail.com
http://sites.google.com/site/dokondr/welcome
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Re: [Haskell-cafe] How to get a file path to the program invoked?
To be precise, $0 always contains the path to the program called. You are right, this path will change depending on location from which the program was called. So $0 is OK for my case, while current directory is unrelated. Try this: #!/bin/sh echo Arg 0: $0 echo All Parameters: [$@] Again, any way to get the same functionality in GHC? On Thu, Dec 1, 2011 at 10:32 PM, Giovanni Tirloni gtirl...@sysdroid.comwrote: On Thu, Dec 1, 2011 at 5:26 PM, dokondr doko...@gmail.com wrote: On the contrary, standard shell variable $0 - contains a full path to the program location in the directory structure, no matter from what directory the program was called. Are you sure? $ zero.sh ./zero.sh $ ./zero.sh ./zero.sh $ /home/gtirloni/zero.sh /home/gtirloni/zero.sh -- Giovanni ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] How to get a file path to the program invoked?
Balazs, thanks! It's great that these packages exist! On Thu, Dec 1, 2011 at 11:17 PM, Balazs Komuves bkomu...@gmail.com wrote: Hello, I'm not subscribed to haskell cafe, but I browse the archives sometimes. As Simon Hengel wrote there, there are two packages on Hackage trying to solve this exact problem (since GHC and the standard library does not provide the necessary information): http://hackage.haskell.org/package/executable-path http://hackage.haskell.org/package/FindBin (Hackage is down at the moment, so I'm not completely sure about the second link). I'm the author of the first one. Balazs ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Amazon AWS storage best to use with Haskell?
Steve, thanks for sharing your experience with AWS! At the moment I have evaluated several NoSQL storage solutions including SimpleDB, Riak, MongoDB and Cassandra. Lessons learned: 1) Storage that SimpleDB provides is too low-level and not very convenient to store dictionaries and other b-tree data structures that my app. works with. 2) simpledb/dev simulator is out of date and does not support the complete feature set of SimpleDB today. Thus, without major rewrite simpledb/dev emulator can not be used for the development. 3) SimpleDB storage is 100% specific to Amazon framework. From this follows that developing directly to SimpleDB interface will make app not portable across different cloud platforms. 4) Cassandra row/column abstraction is awkward for Data.Map structures that my app needs. 5) Riak provides convenient bucket/key/value abstraction and works in robust to failure node framework. REST/JSON protocol is simple to use, yet it is inefficient for data exchanges used by my app. I couldn't find simple libraries for binary exchange that Riak also supports. 6) MongoDB answers my requirements best of all - it is powerful on a server side (Javascript filters, etc) and works with efficient communication protocol based on BSON data exchange. I also plan to use RabitMQ for communication between several Haskell processes and Java Web front-end that my app incorporates. It would be great to know what tools people use in the cloud (AWS, etc.) to communicate Web front-end with rest of the (Haskell) system ? What Haskell tools to build Web front-end? Thanks! Dmitri On Wed, Nov 16, 2011 at 9:01 PM, Steve Severance st...@medwizard.netwrote: We use AWS extensively. We use the aws package and have contributed to it, specifically SQS functionality. I will give you the rundown of what we do. We moved off of SimpleDb and now use mondodb. The reason is that simple db seemed to have problems with write pressure and there are not good tools for profiling your queries. My main application is extremely write heavy with a single instance needing to do 100s or 1000s of writes a second. Mongodb has worked well for us. I am scared of things like cassandra having looked at the code, however some people have made it work. We store data such as crawled web pages in S3. The files are lzma compressed and the data format is built on protocol buffers. We picked lzma for both storage costs of cold data and the fact that the pipe between S3 and EC2 is somewhat limited and we want to make the most effective use of it as possible. In my experience AWS simulators are more trouble than they are worth since they don't accurately model the way AWS will respond to you under load. The free tier at AWS should allow you to experiment with building an app. The first couple of months of development cost us less than $1. Steve On Tue, Nov 1, 2011 at 1:27 AM, dokondr doko...@gmail.com wrote: On Tue, Nov 1, 2011 at 10:53 AM, Neil Davies semanticphilosop...@gmail.com wrote: Word of caution Understand the semantics (and cost profile) of the AWS services first - you can't just open a HTTP connection and dribble data out over several days and hope for things to work. It is not a system that has that sort of laziness at its heart. AWS doesn't supply a traditional remote file store semantics - is queuing, simple database and object store have all been designed for large scale systems being offered as a service to a (potentially hostile) large set of users - you can see that in the way that things are designed. There are all sorts of (sensible from their point of view) performance related limits and retries. The challenge in designing nice clean layers on top of AWS is how/when to hide the transient/load related failures. As a straw-man approach I would go first to NData.Map backed by Data.Map with addition of flush function to write Data.Map to external key-value store / NoSQL DB. Another requirement for NData.Map is concurrent consistency, so different clients could modify its state preserving happen-before relationship. For this I would add to NData.Map a reftresh function, that updates local copy from external key-value store. As for hSimpleDB package, it looks like it doesn't build on ghc7: http://hackage.haskell.org/package/hSimpleDB The hSimpleDB package Interface to Amazon's SimpleDB service. PropertiesVersions0.1 http://hackage.haskell.org/package/hSimpleDB-0.1, 0.2 http://hackage.haskell.org/package/hSimpleDB-0.2, *0.3* Dependenciesbase http://hackage.haskell.org/package/base-3.0.3.2 (≥3 ≤4), bytestringhttp://hackage.haskell.org/package/bytestring-0.9.2.0, Crypto http://hackage.haskell.org/package/Crypto-4.2.4, dataenchttp://hackage.haskell.org/package/dataenc-0.14.0.2, HTTP http://hackage.haskell.org/package/HTTP-4000.1.2, hxthttp://hackage.haskell.org/package/hxt-9.1.4, network http://hackage.haskell.org/package/network-2.3.0.7, old-localehttp
Re: [Haskell-cafe] Haskell Platform for OSX ?
On Wed, Nov 9, 2011 at 3:48 AM, Rogan Creswick cresw...@gmail.com wrote: On Tue, Nov 8, 2011 at 4:30 PM, Giovanni Tirloni gtirl...@sysdroid.com wrote: 3) How to install it into a separate location so it would not ruin my current platform? You can install it under a different username. Haskell Platform (HP) is installed for *all* users in one location at OSX: /Library/Frameworks/GHC.framework/Versions/ total 8 drwxrwxr-x 4 root admin 136 21 feb 2011 . drwxrwxr-x 5 root admin 170 21 feb 2011 .. drwxrwxr-x 4 root admin 136 11 jun 2010 612 lrwxr-xr-x 1 user staff3 21 фев 2011 Current - 612 1) How different username will help here? 2) Is there any way to see what packages HP includes without actually installing it? Some online document listing HP packages? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Easiest to use NoSQL storage with Haskell?
Hi, What Haskell package to work with NoSQL storage is both mature and easiest to use? I need persistent storage for simple key/value lists (not complex JSON docs). CouchDB and Cassandra seems to be overkill for my needs. What about Riak, MongoDB, Voldemort, etc. ? Thanks! Dmitri. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskell Platform for OSX ?
On Wed, Nov 9, 2011 at 2:11 PM, Giovanni Tirloni gtirl...@sysdroid.comwrote: I meant install new packages through cabal under a different username. The cabal repo should be localized unless you specify --global Please see Rogan's suggestions. Thanks for your help! In case I upgrade to the latest Haskell Platform, what will happen to packages already installed in my ~/.cabal folder? Some of these are quite old and most probably will be incompatible with GHC 7 Does upgrade process remove old and create anew ~/.cabal folder? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Easiest to use NoSQL storage with Haskell?
On Wed, Nov 9, 2011 at 5:46 PM, Daniel Schoepe dan...@schoepe.org wrote: On Wed, 9 Nov 2011 13:59:46 +0300, dokondr doko...@gmail.com wrote: Hi, What Haskell package to work with NoSQL storage is both mature and easiest to use? I need persistent storage for simple key/value lists (not complex JSON docs). CouchDB and Cassandra seems to be overkill for my needs. What about Riak, MongoDB, Voldemort, etc. ? persistent (part of yesod, but useable without other yesod libraries) is quite pleasant to use and supports MongoDB: http://hackage.haskell.org/package/persistent-0.6.4 http://hackage.haskell.org/package/persistent-mongoDB-0.6.3 Cheers, Daniel I am wondering if Database.Persist can work with key/value storage such as Riak or SimpleDB where records are lists of key/value pairs and any two lists can have different keys? Is simple implementation of 'persistent' based on files with key/value records possible? For example 'persistent' based on KyotoCabinet package? (http://hackage.haskell.org/package/KyotoCabinet)http://hackage.haskell.org/package/KyotoCabinet Dmitri ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Easiest to use NoSQL storage with Haskell?
On Wed, Nov 9, 2011 at 8:41 PM, Bas van Dijk v.dijk@gmail.com wrote: On 9 November 2011 11:59, dokondr doko...@gmail.com wrote: What Haskell package to work with NoSQL storage is both mature and easiest to use? I need persistent storage for simple key/value lists (not complex JSON docs). If your data fits in RAM then acid-state is also an option: http://hackage.haskell.org/package/acid-state It's used as the storage library for the new hackage server. I need to share data across processes running both on the same node or different nodes. Every process has its own memory space. Can acid-state memory be shared between several system processes? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] cabal install: Could not find module `Text.XML.HXT.Arrow'
Hi, On Mac OSX, ghc-6.12.3, I have successfully installed the 'hxt' package: http://hackage.haskell.org/package/hxt-8.5.2 Registering hxt-9.1.4... Installing library in /Users/user/.cabal/lib/hxt-9.1.4/ghc-6.12.3 Now when I try to install hSimpleDB ( http://hackage.haskell.org/package/hSimpleDB) I get the following error: cabal install hSimpleDB ... Registering HTTP-4000.0.9... Installing library in /Users/user/.cabal/lib/HTTP-4000.0.9/ghc-6.12.3 Registering HTTP-4000.0.9... Configuring hSimpleDB-0.3... Preprocessing library hSimpleDB-0.3... Building hSimpleDB-0.3... src/Network/AWS/Authentication.hs:47:7: Could not find module `Text.XML.HXT.Arrow': Use -v to see a list of the files searched for. cabal: Error: some packages failed to install: hSimpleDB-0.3 failed during the building phase. The exception was: ExitFailure 1 Any ideas how to solve this? Thanks! Dmitri ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] cabal install: Could not find module `Text.XML.HXT.Arrow'
Thanks, Alas adding '--constraint=hxt==9.0.\*' after cabal-install command does not help. I get the same error. On Tue, Nov 8, 2011 at 2:10 PM, Erik Hesselink hessel...@gmail.com wrote: This is because hSimpleDB doesn't specify version ranges on its dependencies, when it should. Since hxt changed its module structure going from 9.0 to 9.1, hSimpleDB doesn't build against 9.0. You can try to build it by adding '--constraint=hxt==9.0.\*' after your cabal-install command. You can also ask the author to add version ranges to the package. Erik On Tue, Nov 8, 2011 at 11:58, dokondr doko...@gmail.com wrote: Hi, On Mac OSX, ghc-6.12.3, I have successfully installed the 'hxt' package: http://hackage.haskell.org/package/hxt-8.5.2 Registering hxt-9.1.4... Installing library in /Users/user/.cabal/lib/hxt-9.1.4/ghc-6.12.3 Now when I try to install hSimpleDB (http://hackage.haskell.org/package/hSimpleDB) I get the following error: cabal install hSimpleDB ... Registering HTTP-4000.0.9... Installing library in /Users/user/.cabal/lib/HTTP-4000.0.9/ghc-6.12.3 Registering HTTP-4000.0.9... Configuring hSimpleDB-0.3... Preprocessing library hSimpleDB-0.3... Building hSimpleDB-0.3... src/Network/AWS/Authentication.hs:47:7: Could not find module `Text.XML.HXT.Arrow': Use -v to see a list of the files searched for. cabal: Error: some packages failed to install: hSimpleDB-0.3 failed during the building phase. The exception was: ExitFailure 1 Any ideas how to solve this? Thanks! Dmitri ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] cabal install: Could not find module `Text.XML.HXT.Arrow'
On Tue, Nov 8, 2011 at 2:31 PM, Audun Skaugen audunskau...@gmail.comwrote: Erik Hesselink wrote: On Tue, Nov 8, 2011 at 12:16, Ivan Lazar Miljenovic ivan.miljeno...@gmail.com wrote: On 8 November 2011 22:10, Erik Hesselink hessel...@gmail.com wrote: This is because hSimpleDB doesn't specify version ranges on its dependencies, when it should. Since hxt changed its module structure going from 9.0 to 9.1, hSimpleDB doesn't build against 9.0. You can try to build it by adding '--constraint=hxt==9.0.\*' after your cabal-install command. You can also ask the author to add version ranges to the package. Is the escape needed if you're using single quotes? I don't know. I always escape *s in shell commands to be sure the shell doesn't expand them, but in most of the cases, it probably works without them. It will likely even work without quotes and without the escape, unless you have files matching the pattern. The single quote doesn't expand anything, so you don't need to escape the *. Actually, this will result in the backslash also being passed to cabal, so I would be surprised if your command works at all. No matter how you escape *, you get the same error: Preprocessing library hSimpleDB-0.3... Building hSimpleDB-0.3... src/Network/AWS/Authentication.hs:47:7: Could not find module `Text.XML.HXT.Arrow': ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] cabal install: Could not find module `Text.XML.HXT.Arrow'
Package Text.XML.HXT.Arrow existed only in 8.5.2 version of hxt: http://hackage.haskell.org/packages/archive/hxt/8.5.2/doc/html/Text-XML-HXT-Arrow.html Yet trying to install with this version produce even more problems: ~cabal --constraint=hxt==8.5.2 install hSimpleDB Resolving dependencies... cabal: cannot configure Crypto-4.2.3. It requires QuickCheck =2.4.0.1 For the dependency on QuickCheck =2.4.0.1 there are these packages: QuickCheck-2.4.0.1, QuickCheck-2.4.1 and QuickCheck-2.4.1.1. However none of them are available. QuickCheck-2.4.0.1 was excluded because tagsoup-0.8 requires QuickCheck ==2.1.* QuickCheck-2.4.1 was excluded because tagsoup-0.8 requires QuickCheck ==2.1.* QuickCheck-2.4.1.1 was excluded because tagsoup-0.8 requires QuickCheck ==2.1.* On Tue, Nov 8, 2011 at 2:43 PM, dokondr doko...@gmail.com wrote: On Tue, Nov 8, 2011 at 2:31 PM, Audun Skaugen audunskau...@gmail.comwrote: Erik Hesselink wrote: On Tue, Nov 8, 2011 at 12:16, Ivan Lazar Miljenovic ivan.miljeno...@gmail.com wrote: On 8 November 2011 22:10, Erik Hesselink hessel...@gmail.com wrote: This is because hSimpleDB doesn't specify version ranges on its dependencies, when it should. Since hxt changed its module structure going from 9.0 to 9.1, hSimpleDB doesn't build against 9.0. You can try to build it by adding '--constraint=hxt==9.0.\*' after your cabal-install command. You can also ask the author to add version ranges to the package. Is the escape needed if you're using single quotes? I don't know. I always escape *s in shell commands to be sure the shell doesn't expand them, but in most of the cases, it probably works without them. It will likely even work without quotes and without the escape, unless you have files matching the pattern. The single quote doesn't expand anything, so you don't need to escape the *. Actually, this will result in the backslash also being passed to cabal, so I would be surprised if your command works at all. No matter how you escape *, you get the same error: Preprocessing library hSimpleDB-0.3... Building hSimpleDB-0.3... src/Network/AWS/Authentication.hs:47:7: Could not find module `Text.XML.HXT.Arrow': ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Haskell Platform for OSX ?
Hi, I am running GHC 6.12.3 at Mac OSX and have numerous problems with 'cabal install' of different packages. For example: ~cabal install mongoDB Resolving dependencies... Configuring mongoDB-1.1.0... Preprocessing library mongoDB-1.1.0... Building mongoDB-1.1.0... ... Control/Monad/MVar.hs:16:34: Module `Control.Exception.Control' does not export `mask' cabal: Error: some packages failed to install: mongoDB-1.1.0 failed during the building phase. The exception was: ExitFailure 1 Questions about current Haskell Platform for OSX 2011.2.0.1. : (http://hackage.haskell.org/platform/mac.html) 1) Where can I find release notes to understand what version of GHC Haskell Platform for OSX 2011.2.0.1 includes? 2) Will I be able to install mongoDB-1.1.0 on this release? 3) How to install it into a separate location so it would not ruin my current platform? Thanks! Dmitri ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Amazon AWS storage best to use with Haskell?
On Tue, Nov 1, 2011 at 5:03 AM, Ryan Newton rrnew...@gmail.com wrote: Any example code of using hscassandra package would really help! I'll ask my student. We may have some simple examples. Also, I have no idea as to their quality but I was pleasantly surprised to find three different amazon related packages on Hackage (simply by searching for the word Amazon in the package list). http://hackage.haskell.org/package/hS3 http://hackage.haskell.org/package/hSimpleDB http://hackage.haskell.org/package/aws It would be great to know if these work. Thinking about how to implement Data.Map on top of hscassandra or any other key-value storage ... For example creating new map with fromList will require to store *all* (key, value) list elements in external storage at once. How to deal with laziness in this case? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Amazon AWS storage best to use with Haskell?
On Tue, Nov 1, 2011 at 10:53 AM, Neil Davies semanticphilosop...@gmail.comwrote: Word of caution Understand the semantics (and cost profile) of the AWS services first - you can't just open a HTTP connection and dribble data out over several days and hope for things to work. It is not a system that has that sort of laziness at its heart. AWS doesn't supply a traditional remote file store semantics - is queuing, simple database and object store have all been designed for large scale systems being offered as a service to a (potentially hostile) large set of users - you can see that in the way that things are designed. There are all sorts of (sensible from their point of view) performance related limits and retries. The challenge in designing nice clean layers on top of AWS is how/when to hide the transient/load related failures. As a straw-man approach I would go first to NData.Map backed by Data.Map with addition of flush function to write Data.Map to external key-value store / NoSQL DB. Another requirement for NData.Map is concurrent consistency, so different clients could modify its state preserving happen-before relationship. For this I would add to NData.Map a reftresh function, that updates local copy from external key-value store. As for hSimpleDB package, it looks like it doesn't build on ghc7: http://hackage.haskell.org/package/hSimpleDB The hSimpleDB package Interface to Amazon's SimpleDB service. PropertiesVersions0.1 http://hackage.haskell.org/package/hSimpleDB-0.1, 0.2 http://hackage.haskell.org/package/hSimpleDB-0.2, *0.3*Dependencies base http://hackage.haskell.org/package/base-3.0.3.2 (≥3 ≤4), bytestring http://hackage.haskell.org/package/bytestring-0.9.2.0, Cryptohttp://hackage.haskell.org/package/Crypto-4.2.4, dataenc http://hackage.haskell.org/package/dataenc-0.14.0.2, HTTPhttp://hackage.haskell.org/package/HTTP-4000.1.2, hxt http://hackage.haskell.org/package/hxt-9.1.4, networkhttp://hackage.haskell.org/package/network-2.3.0.7, old-locale http://hackage.haskell.org/package/old-locale-1.0.0.3, old-time http://hackage.haskell.org/package/old-time-1.0.0.7, utf8-string http://hackage.haskell.org/package/utf8-string-0.3.7License BSD3AuthorDavid Himmelstrup 2009, Greg Heartsfield 2007MaintainerDavid Himmelstrup lem...@gmail.comCategoryDatabasehttp://hackage.haskell.org/packages/archive/pkg-list.html#cat:database, Web http://hackage.haskell.org/packages/archive/pkg-list.html#cat:web, Networkhttp://hackage.haskell.org/packages/archive/pkg-list.html#cat:networkUpload dateThu Sep 17 17:09:26 UTC 2009Uploaded byDavidHimmelstrupBuilt onghc-6.10, ghc-6.12Build failureghc-7.0 (loghttp://hackage.haskell.org/packages/archive/hSimpleDB/0.3/logs/failure/ghc-7.0 ) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Persistent Concurrent Data Structures
Hi, Please comment on the idea and advise on steps to implement it. Real world applications need persistent data, that can be accessed and modified concurrently by several clients, in a way that preserves happen-before relationship. Idea: Design and implement Persistent Concurrent Data Types in Haskell. These data types should mirror existing Data.List , Data.Map and similar types but provide persistency and support consistent concurrent access and modification (or simply - concurrency). Persistency and concurrency should be configurable through these type interfaces. Configuration should include: 1) Media to persist data, such as file, DBMS, external key-value store (for example Amazon SimpleDB, CouchDB, MongoDB, Redis, etc) 2) Caching policy - when (on what events) and how much data to read/write from/to persistent media. Media reads / writes can be done asynchronously in separate threads. 3) Concurrency configuration: optimistic or pessimistic data locking. One may ask why encapsulate persistency and concurrency in the data type instead of using native storage API, such as for example key-value / row-column API that NoSQL databases provide? The answer is simple: APIs that your code use greatly influence the code itself. Using low-level storage API directly in your code results in bloated obscure code, or you need to encapsulate this low-level API in clear and powerful abstractions. So why not to do this encapsulation once and for all for such powerful types as Data.Map, for example, and forget all Cassandra and SimpleDB low-level access method details? When the right time comes and you will need to move your application to the next new shiny_super_cloud, you will just write the implementation of NData.Map backed by Data.Map in terms of low-level API of this super-cloud. (Side note: I really need such a NData.Map type. I was requested to move my code that heavily uses Data.Map and simple text file persistence into Amazon AWS cloud. Looking at SimpleDB API, I realized that I will have to rewrite 90% of code. This rewrite will greatly bloat my code and will make it very unreadable. In case I had NData.Map I would just switch implementation from 'file' to SimpleDB persistency inside my NData.Map type.) Implementation: To start playing with this idea, NData.Map persisted in a regular file will do, no concurrency yet. Next step - NData.Map persisted in SimpleDB or Cassandra or Redis, with concurrent access supported. So it looks like NData.Map should be a monad ... Any ideas on implementation and similar work? Thanks! Dmitri --- http://sites.google.com/site/dokondr/welcome ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Persistent Concurrent Data Structures
Thanks everybody for advice! I'll try to clarify what I mean by persistence and concurrent access that preserves happens-before relationship. 1) Persistence - imagine Haskell run-time executing in infinite physical memory. My idea is to implement really huge, almost infinite memory in the cloud of one or another type. Nothing more nothing less, nothing imperative, exactly the same environment that GHC runtime works today, but extended to huge virtual memory in the cloud. 2) Concurrent access that preserves happens-before relationship. Before talking about transactions, I would use locking data structures in two different ways: - Optimistic lock - everybody can read and write / delete simultaneously, system ensures only happens-before relationship. In other words Best Effort Modification - you can try to modify data, but there is no guarantee that your modification will work. - Pessimistic lock - when you get lock - structure is all yours as long as you held the lock - everybody else can only read, happens-before relationship is ensured at all times. About happens-before relationship: http://en.wikipedia.org/wiki/Happened-before ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Persistent Concurrent Data Structures
On Wed, Nov 2, 2011 at 3:12 AM, dokondr doko...@gmail.com wrote: Thanks everybody for advice! I'll try to clarify what I mean by persistence and concurrent access that preserves happens-before relationship. 1) Persistence - imagine Haskell run-time executing in infinite physical memory. My idea is to implement really huge, almost infinite memory in the cloud of one or another type. Nothing more nothing less, nothing imperative, exactly the same environment that GHC runtime works today, but extended to huge virtual memory in the cloud. I am afraid I am confused everybody, didn't mean it, sorry. I understand that infinite physical memory is not quite the same that implementing NData.* on top of some cloud framework. Yet NData.* may be the first step in this direction. Infinite memory will require support in Haskell run-time, run-time distributed across many physical instances. Yet, it looks like physical memory will eventually will be very huge virtual memory persistent in the cloud for some period of time. IMHO this will simplify programming model considerably. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Amazon AWS storage best to use with Haskell?
Hi, Please share your experience / ideas on AWS storage most friendly to Haskell. So far I store my data mostly in Data.Map structures serialized to text files with write / read functions. Now I was requested to move my app and data to Amazon cloud. As far as I know there are two main storage types that Amazon provides: S3 - basic block storage and SimpleDB ( http://docs.amazonwebservices.com/AmazonSimpleDB/latest/GettingStartedGuide/ ) Questions: 1) I would like to continue working with my data using abstractions similar to the ones that Data.Map provides. Any ideas how to iterate and modify SimpleDB records in a similar powerful way as provided by Data.Map? Or maybe S3? 2) It would be great to do development and testing offline without actually connecting to AWS S3 / SimpleDB. Are there any AWS simulators + Haskell libraries that will allow to do such an offline development? 3) Any experience / ideas with Haskell libs for NoSQL, not AWS-native, storages, that will run well both offline and in AWS? 4) My code processes hundreds of messages. Every message is processed in exactly the same way as the others. So the code can be easily parallelized. Any Haskell frameworks that will allow me to run this code in a simple concurrency model? Thanks! Dmitri ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Amazon AWS storage best to use with Haskell?
On Mon, Oct 31, 2011 at 6:50 PM, John Lenz l...@math.uic.edu wrote: 4) My code processes hundreds of messages. Every message is processed in exactly the same way as the others. So the code can be easily parallelized. Any Haskell frameworks that will allow me to run this code in a simple concurrency model? Yes, there are many options. http://www.haskell.org/**haskellwiki/GHC/Concurrencyhttp://www.haskell.org/haskellwiki/GHC/Concurrency John, thanks for detailed reply! I am looking at Haskell Concurrency wiki, but can not figure out which framework - STM, sparks, threads, etc. Amazon AWS will be able to scale? As far as I know, to scale CPU and program memory in Amazon, all you can ask from AWS is to start some number of additional extra VMs. Every VM contains a complete image of your OS and executables, all images are exactly the same. That's fine with me as currently all my workflow tasks are performed by separately compiled Haskell executables communicating via regular files. So to reformulate my question: - Does any Haskell framework exist that allow to orchestrate separate processes (NOT threads that share the same process memory)? On the other hand, in case there is a way to make Amazon AWS to scale Haskell STM, sparks, threads, etc. - I would happily rewrite my Haskell code to use these frameworks. So my second question: - Is there a way to make Amazon AWS to scale Haskell STM, sparks, threads or any other Haskell concurrency frameworks? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Amazon AWS storage best to use with Haskell?
On Mon, Oct 31, 2011 at 6:50 PM, John Lenz l...@math.uic.edu wrote: CouchDB works great, although I decided to go with SimpleDB since then it is amazon's problem to scale and allocate disk and so forth, which I like better. For couchdb, you can use my package couchdb-enumerator on hackage. Regarding CouchDB. So far I have my records keyed by Id and stored in Data.Map which I serialize to text file. Using Data.Map functions I do many operations with these records including mapping functions over keys and values, accumulation, lookup, intersection, union etc. When I move this data to CouchDB and start using couchdb-enumerator to work with it, how natural will it be to implement all these functions that I use from Data.Map? Or maybe it makes more sense to store my serialized Data.Map as a blob in CouchDB? And do not use views or similar CouchDB / SimpleDB interfaces at all? Just retrieve necessary blob and deserialize it to Data.Map, update and then store modified blob to CouchDB again? It would be great if somebody had time to implement Data.List, Data.Map, etc on top of generic NoSQL DB interface with specific instances for CouchDB, SimpleDB, etc. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Amazon AWS storage best to use with Haskell?
On Tue, Nov 1, 2011 at 12:07 AM, Ryan Newton rrnew...@gmail.com wrote: ... For a NOSQL layer -- I'm looking for the answer to that same question myself! We've been experimenting with Cassandra (used via the hscassandra package based in turn on cassandra-thrift). Already it's clear that there are many areas that need work. The Haskell code generated by Thrift itself has a lot of room for improvement (for the intrepid hacker: cycles there would be well-spent). Any example code of using hscassandra package would really help! ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Libraries to compare trees?
On Fri, Oct 28, 2011 at 2:31 AM, Ivan Lazar Miljenovic ivan.miljeno...@gmail.com wrote: Well, for arbitrary directed graphs, FGL is probably your best bet, or roll-your-own. _But_ you'll need to write the parser yourself using something like trifecta, uu-parsinglib, polyparse, parsec, etc. It would help if you described the structure of these graphs and what kind of support you'd want in a data structure. Thanks for the feedback! As I wrote in first message I need to compare both structure and node contents of two graphs, find similar sub-graphs, and need some metric to measure distance between two graphs. These graphs are produced by POS (part of speech) sentence tagging. POS tagging is done by Standford statistical parser: http://nlp.stanford.edu/software/lex-parser.shtml For example in the graph G1: (ROOT (S (NP (DT The) (NN voice) (NN quality)) (VP (VBD was) (ADJP (JJ clear) (RB too))) (. .))) G1 has an NP node (lets call this sub-graph SG1) which has three child leaf nodes: (DT The) (NN voice) (NN quality), where DT, NN - nodes names, and The, voice, quality - corresponding leaf values of these nodes. I need to compare this graph with graph G2: (ROOT (S (SBAR (IN Although) (S (NP (DT the) (NN battery) (NN life)) (VP (VBD was) (RB not) (ADJP (JJ long) (, ,) (NP (DT that)) (VP (VBZ is) (VP (VBN ok) (PP (IN for) (NP (PRP me) (. .))) G2 also has the NP node (let's call it sub-graph SG2) which also has three child leaf nodes: (DT the) (NN battery) (NN life)) I need to find that G1 and G2 has sub-graphs SG1 and SG2 with the similar structure, but with different values of the leaf nodes. I also need to devise some general metric that will allow me to estimate distance between any two graphs. This distance should account both for structural and leaf-node values similarity. It would be easier to measure distance between vectors then graphs. So I am thinking how to convert directed graph (that results from POS tagging) into vector. Any ideas, links here? Thanks! On 28 October 2011 00:27, dokondr doko...@gmail.com wrote: My mistake: need advice on libraries and data types not for trees but for directed graphs. On Thu, Oct 27, 2011 at 4:49 PM, dokondr doko...@gmail.com wrote: Please advise on Haskell libraries to compare trees in textual representation. I need to compare both structure and node contents of two trees, find similar sub-trees, and need some metric to measure distance between two trees. Also need advice on simple parser to convert textual tree representation into a data type convenient for tree manipulation (comparison, matching, etc.) What data type to use for trees with arbitrary structure? Example trees: *** Tree 1: (ROOT (S (NP (DT The) (NN voice) (NN quality)) (VP (VBD was) (ADJP (JJ clear) (RB too))) (. .))) *** Tree 2: (ROOT (S (SBAR (IN Although) (S (NP (DT the) (NN battery) (NN life)) (VP (VBD was) (RB not) (ADJP (JJ long) (, ,) (NP (DT that)) (VP (VBZ is) (VP (VBN ok) (PP (IN for) (NP (PRP me) (. .))) Thanks! Dmitri ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- Ivan Lazar Miljenovic ivan.miljeno...@gmail.com IvanMiljenovic.wordpress.com -- All the best, Dmitri O. Kondratiev This is what keeps me going: discovery doko...@gmail.com http://sites.google.com/site/dokondr/welcome ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Libraries to compare trees?
Please advise on Haskell libraries to compare trees in textual representation. I need to compare both structure and node contents of two trees, find similar sub-trees, and need some metric to measure distance between two trees. Also need advice on simple parser to convert textual tree representation into a data type convenient for tree manipulation (comparison, matching, etc.) What data type to use for trees with arbitrary structure? Example trees: *** Tree 1: (ROOT (S (NP (DT The) (NN voice) (NN quality)) (VP (VBD was) (ADJP (JJ clear) (RB too))) (. .))) *** Tree 2: (ROOT (S (SBAR (IN Although) (S (NP (DT the) (NN battery) (NN life)) (VP (VBD was) (RB not) (ADJP (JJ long) (, ,) (NP (DT that)) (VP (VBZ is) (VP (VBN ok) (PP (IN for) (NP (PRP me) (. .))) Thanks! Dmitri ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Libraries to compare trees?
My mistake: need advice on libraries and data types not for trees but for directed graphs. On Thu, Oct 27, 2011 at 4:49 PM, dokondr doko...@gmail.com wrote: Please advise on Haskell libraries to compare trees in textual representation. I need to compare both structure and node contents of two trees, find similar sub-trees, and need some metric to measure distance between two trees. Also need advice on simple parser to convert textual tree representation into a data type convenient for tree manipulation (comparison, matching, etc.) What data type to use for trees with arbitrary structure? Example trees: *** Tree 1: (ROOT (S (NP (DT The) (NN voice) (NN quality)) (VP (VBD was) (ADJP (JJ clear) (RB too))) (. .))) *** Tree 2: (ROOT (S (SBAR (IN Although) (S (NP (DT the) (NN battery) (NN life)) (VP (VBD was) (RB not) (ADJP (JJ long) (, ,) (NP (DT that)) (VP (VBZ is) (VP (VBN ok) (PP (IN for) (NP (PRP me) (. .))) Thanks! Dmitri ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] The best way to call Java from Haskell?
On Tue, Oct 11, 2011 at 12:42 PM, Yitzchak Gale g...@sefer.org wrote: Dmitri wrote: I need to call Stanford NLP Parser from Haskell (unfortunately Haskell does not have a similar one)... Just out of curiosity, why do you not consider GF at all similar? To an outsider like me, there does appear to be quite a bit of similarity. http://www.grammaticalframework.org/ Thanks, Yitz As I understand GF is well suited for parsing well defined formal languages. Not sure that GF can be used as NLP parser for blog messages that I need. Please correct me if I am wrong. As a general note, Java has tons of useful libraries that will take infinite time to re-implement in Haskell. To my mind it makes a lot of sense to have a reliable mechanism to call Java from Haskell. BTW, yet another way to do this: wrap Java library in RESTFUL web service ) -- All the best, Dmitri O. Kondratiev This is what keeps me going: discovery doko...@gmail.com http://sites.google.com/site/dokondr/welcome ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] The best way to call Java from Haskell?
Hi, I need to call Stanford NLP Parser from Haskell (unfortunately Haskell does not have a similar one): http://nlp.stanford.edu/software/lex-parser.shtml What would be the most reliable framework for this? Thanks! Dmitri ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Function composition in run-time?
On Wed, Aug 24, 2011 at 4:44 PM, Iustin Pop ius...@google.com wrote: On Wed, Aug 24, 2011 at 04:35:42PM +0400, dokondr wrote: Hi, What is the Haskell way to compose functions in run-time? Depending on configuration parameters I need to be able to compose function in several ways without recompilation. A simple alternative to if would be: options = [ (foo, f1 . f2 . f3) , (bar, f1 . f3 )] and then lookup param options. I don't know if this is what you're looking for, though. Thanks! Yes, this is what I need - simple and easy. Yet, how function application will work in this case ? I mean after lookup returns me a composition ... need to check what type will it be. -- All the best, dokondr ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Function composition in run-time?
On Wed, Aug 24, 2011 at 4:52 PM, Arseniy Alekseyev arseniy.alekse...@gmail.com wrote: If your functions have the same type, then you can easily collect them in a data structure, say list, and fold that. For example: function :: String - (String - String) function f1 = f1 function f2 = f2 function f3 = f3 runAUserSpecifiedComposition :: String - F runAUserSpecifiedComposition = foldl (.) id . map function . words runAUserSpecifiedComposition f1 f2 f3 should be equal to (f1 . f2 . f3) now. This is a nice one, looks already like tiny DSL ) I think I've got the main idea - enumerate in my program all function compositions in some data structure for Haskell to compile, and the associate these with parameter values in external file. Thanks everybody! dokondr ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskell Actors, Linda, publish / subscribe models?
On Mon, Aug 15, 2011 at 12:36 PM, Holger Reinhardt hreinha...@gmail.comwrote: Hi, the actor package seems unmaintained and probably doesn't fit your needs. If you want to implement some kind of publish/subscribe system over the network, I'd suggest you take a look at ZeroMQ[1] and AMQP[2]. AMQP is probably easier to get started with, but it requires you to set up a dedicated broker, which (if you have very high throughput) might become a bottleneck. ZeroMQ, on the other hand, allows for a more decentralized architecture. Regards, Holger [1] http://hackage.haskell.org/package/zeromq-haskell [2] http://hackage.haskell.org/package/amqp Thanks! I will try these out. I wish I could find something that will provide a *single* publish / subscribe framework to work with threads *both* in the same and separate address spaces. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskell Actors, Linda, publish / subscribe models?
On Mon, Aug 15, 2011 at 11:41 PM, Ryan Newton rrnew...@gmail.com wrote: It seems that the recent Cloud Haskell paper is relevant: http://research.microsoft.com/en-us/um/people/simonpj/papers/parallel/remote.pdf The repo is here: https://github.com/jepst/CloudHaskell I haven't tried it yet myself but would like to. Cheers, -Ryan Thanks for the really great news! Finally Erlang actor model of communication comes to Haskell! I hope that one day Haskell will also evolve to provide dynamic code update as Erlang does. It would then be the ideal PL for reliable programming of adaptive, distributed real-world systems! -- All the best, Dmitri O. Kondratiev This is what keeps me going: discovery doko...@gmail.com http://sites.google.com/site/dokondr/welcome ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskell Actors, Linda, publish / subscribe models?
On Sat, Aug 13, 2011 at 3:54 PM, dokondr doko...@gmail.com wrote: Hi, I am trying to figure out what Haskell libraries can be used to build publish / subscribe communication between threads running both in the same and different address spaces on the net. For my needs any of these models will work: - Actors [ http://en.wikipedia.org/wiki/Actor_model ] - Linda tuple space [ http://en.wikipedia.org/wiki/Linda_%28coordination_language%29 ] - Publish / subscribe [ http://en.wikipedia.org/wiki/Java_Message_Service#Publish.2Fsubscribe_model] I need to build a framework to coordinate task producers / consumers distributed in the same and different address spaces. I need to scale a data processing application somewhat Hadoop-like way yet in more flexible manner, without Hadoop-specific distributed FS constraints. Looking through Applications and libraries/Concurrency and parallelism: http://www.haskell.org/haskellwiki/Applications_and_libraries/Concurrency_and_parallelism I found Haskell actor package [ http://hackage.haskell.org/cgi-bin/hackage-scripts/package/actor ] that fails to build with ghc 7.0. Please advise on latest working libraries. Thanks! Have anybody used Haskell actor package [ http://hackage.haskell.org/cgi-bin/hackage-scripts/package/actor ]? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Haskell Actors, Linda, publish / subscribe models?
Hi, I am trying to figure out what Haskell libraries can be used to build publish / subscribe communication between threads running both in the same and different address spaces on the net. For my needs any of these models will work: - Actors [ http://en.wikipedia.org/wiki/Actor_model ] - Linda tuple space [ http://en.wikipedia.org/wiki/Linda_%28coordination_language%29 ] - Publish / subscribe [ http://en.wikipedia.org/wiki/Java_Message_Service#Publish.2Fsubscribe_model] I need to build a framework to coordinate task producers / consumers distributed in the same and different address spaces. I need to scale a data processing application somewhat Hadoop-like way yet in more flexible manner, without Hadoop-specific distributed FS constraints. Looking through Applications and libraries/Concurrency and parallelism: http://www.haskell.org/haskellwiki/Applications_and_libraries/Concurrency_and_parallelism I found Haskell actor package [ http://hackage.haskell.org/cgi-bin/hackage-scripts/package/actor ] that fails to build with ghc 7.0. Please advise on latest working libraries. Thanks! -- All the best, Dmitri O. Kondratiev This is what keeps me going: discovery doko...@gmail.com http://sites.google.com/site/dokondr/welcome ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Approximate String Matching
Hi, I am looking for Haskell libraries to do approximate string matching: http://en.wikipedia.org/wiki/Approximate_string_matching I need this to reduce a set of English word variants with spelling errors to a single canonical dictionary entry. Any libraries to work with spelling will also help. Thanks, Dmitri ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Library for Sparse Vectors?
Hi, Can't find on hackage any sparse vector library. Does such thing exist? I need efficient storage and dot product calculation for very sparse vectors with about 10 out of 40 000 non-zero components. One solution would be to represent Sparse Vector as Data.Map with (component_index, component_value) pairs to store non-zero components of the vector. In this case, for example, calculating cosine similarity ( http://en.wikipedia.org/wiki/Cosine_similarity) for for every pair of 10 000 vectors, would not be very nice and efficient, I am afraid. Thanks! ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Library for Sparse Vectors?
Thanks for the detailed reply and example! Using IntMap as a vector seems to be a good idea. In your example: 1) I would use: dot = dot' * dot' dot' = sum . elems . intersectionWith (*) norm = sum . fmap (**2) . elems instead of: dot = sum . elems . intersectionWith (*) norm = (**0.5) . sum . fmap (**2) . elems 2) I don't understand the syntax: cosineSimilarity $ lookup x space * lookup y space What are $ and *? Thanks, Dmitri On Wed, Jul 27, 2011 at 1:46 AM, Alexander Solla alex.so...@gmail.comwrote: On Tue, Jul 26, 2011 at 1:30 PM, dokondr doko...@gmail.com wrote: Hi, Can't find on hackage any sparse vector library. Does such thing exist? I need efficient storage and dot product calculation for very sparse vectors with about 10 out of 40 000 non-zero components. One solution would be to represent Sparse Vector as Data.Map with (component_index, component_value) pairs to store non-zero components of the vector. I would make a different suggestion: Store a Set (or maybe an IntMap) of (IntMap scalar)s. In other words, let each vector be represented by an IntMap whose key represents the n'th component of the vector, and whose value is the proper scalar. In this case, for example, calculating cosine similarity ( http://en.wikipedia.org/wiki/Cosine_similarity) for for every pair of 10 000 vectors, would not be very nice and efficient, I am afraid. Given two (IntMap Double)s a and b, I would compute the projection of a along b as cosineSimilarity :: IntMap Double - IntMap Double - Double cosineSimilarity a b = (dot a b) / ((norm a) * (norm b)) where dot = sum . elems . intersectionWith (*) norm = (**0.5) . sum . fmap (**2) . elems The only part I find tricky is enumerating all 1^2 pairs pairs :: Int - [Int] pairs dim = do x - [1..dim] y - [1..dim] return (x,y) and computing the projection for each pair: projections :: Floating scalar = IntMap (IntMap scalar) - Map (Int, Int) scalar projections space = let dimensions = undefined -- find max key in elements of space? m_projection space x y = cosineSimilarity $ lookup x space * lookup y space in fromList . filter (isMaybe . snd) . fmap (\(x,y) - ((x,y), m_projection space x y) . pairs $ dimensions ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
