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ANN: BUG FIX release of regex-tdfa-1.1.2
by ChrisK 05 May '09

05 May '09

Hello, While occasionally and slowly updating the future version of regex-tdfa I found a bug that exists in the released 1.1.1 version. It was just a matter of passing the wrong value into a function, so was easy to fix when I figured it out. The test case triggered an impossible "error" call and so I know this can kill a program that uses a buggy version of this library. Please upgrade regex-tdfa to version 1.1.2 which is available on hackage at: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/regex-tdfa Cheers, Chris

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How to understand the fmap here ?
by z_axis 05 May '09

05 May '09

The following code snippets is from xmonad: -- Given a window, find the screen it is located on, and compute -- the geometry of that window wrt. that screen. floatLocation :: Window -> X (ScreenId, W.RationalRect) --....... rr <- snd `fmap` floatLocation w Prelude> :i fmap class Functor f where fmap :: (a -> b) -> f a -> f b It seems it is different from the definition of fmap ? sincerely! 2009-05-05 z_axis

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StateT IO Action on `onKeyPress`
by Andy Stewart 05 May '09

05 May '09

Hi all, I have a function named `keymapTest` need moand state WindowListT, and WindowListT is `type WindowListT = StateT WindowList IO`. when i add "(\event -> keymapTest winList event >> return False)" after `onKeyPress` for handle key press event, i got GHC error: Manatee.hs:57:58: Couldn't match expected type `IO a' against inferred type `WindowListT Bool' In the first argument of `(>>)', namely `keymapTest winList event' In the expression: keymapTest winList event >> return False In the second argument of `onKeyPress', namely `(\ event -> keymapTest winList event >> return False)' So function `onKeyPress` just accept *one* IO-action? Have a way to fix above problem? Any help? Thanks! -- Andy Below is source code of Manatee.hs file. ------------------------------> Manatee.hs start <------------------------------ module Main where import Text.Printf import Data.Monoid import Data.List import Data.Maybe import Control.Monad import Control.Monad.State import Control.Applicative import Data.IORef import Graphics.UI.Gtk hiding (Window, windowNew, get) import Graphics.UI.Gtk.SourceView import Graphics.UI.Gtk.Abstract.Widget import Manatee.Event import Manatee.Buffer import Manatee.WindowList import Manatee.Pane import Manatee.Statusbar import Manatee.Utils import Manatee.Window import qualified Data.Set as Set import qualified Graphics.UI.Gtk.Windows.Window as W import qualified Graphics.UI.Gtk.Gdk.Events as E main :: IO () main = do -- Init. initGUI -- Root frame. rootFrame <- W.windowNew rootFrame `onDestroy` mainQuit -- quit main loop when root frame close -- Root frame status. windowFullscreen rootFrame -- fullscreen -- Windows list. let windowsList = WindowList 0 Set.empty evalStateT (do -- Window 1 window1 <- windowNewWithBuffer DTop "test" liftIO $ containerAdd rootFrame $ windowPaned window1 (window2, window3) <- windowSplitVertically window1 (window4, window5) <- windowSplitHorizontally window3 winList <- windowListGetList liftIO $ rootFrame `onKeyPress` (\event -> keymapTest winList event >> return False) -- Handle window content synchronous. windowHandleSynchronous ) windowsList -- Loop widgetShowAll rootFrame -- display all widget mainGUI keymapTest :: [Window] -> E.Event -> WindowListT Bool keymapTest winList event = do window <- liftIO $ windowFindFocus winList case window of Just x -> handleKeyPress x event Nothing -> return False handleKeyPress :: Window -> E.Event -> WindowListT Bool handleKeyPress window ev = do liftIO $ case eventTransform ev of Nothing -> return False Just e -> do let display = statusbarOutputSubitemSetText $ paneStatusbar $ windowPane $ window eventName = eventGetName e case eventName of -- Window commands. "M-t" -> display "windowSplitVertically" -- "M-t" -> windowSplitVertically window >> return False _ -> display $ printf "%s undefined." eventName ------------------------------> Manatee.hs end <------------------------------

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Re: Using Takusen is a real intellectual challenge
by oleg＠okmij.org 05 May '09

05 May '09

Perhaps you might find the following code, relying on low-level Takusen's functions, useful http://darcs.haskell.org/takusen/Database/PostgreSQL/Test/pgaccess.hs The code is a stand-alone program that does the following: docstrings = [ "A helper to access a PostgreSQL from a `scripting' language.", "This function attempts to closely emulate `dbaccess' of Informix.", "The goal is to have my Scheme-to-Informix interface work with", "PostgreSQL with minimal changes.", "", "Synopsys:", " dbaccess <conn-parms>", "where <conn-parms> is the string of database connection parameters.", "", "The program connects to the database and listens on its standard", "input for a SQL command. A command is an ASCII sequence terminated by", "NL-NULL-NL.", "If the command is other than SELECT or COPY, we submit it to the database.", "On success, no reply is generated, and we wait for a new command.", "If the command starts with a /*simple*/ SELECT, we expect few rows.", "We submit the query to the database and write the result to stdout.", "If the command was SELECT, we make a query and write the result,", "in groups, to the stdout. Each group of results has the form:", " 0 NL", " for the last group of results", " <nrows> <space> <ncols> NL", " followed by the matrix of <nrows> * <ncols> field values in the", " row-major order. Each field value has the form", " <length>NL<value>", " where <length> is the length of the value proper (no NL).", "", "If the command was COPY, we assume ", " COPY /*<len> fname*/ table ... FROM STDIN...", " where <len> is the length of the file name. We open the file and", " send its contents to the server", "", "Any error causes the termination of this program.", "We log all the results to stderr." ] The above was my attempt at comments shared between compile-time and run-time. HERE documents would have certainly helped; I hope Haskell will get them one day. As the comments show, pgaccess is a very simple program to endow any scripting language (Scheme in my case) to communicate with a PostgreSQL database. The scripting language communicates with pgaccess via a pipe; thus the language itself needs to know nothing about databases and need not depend on any database libraries. The code has been designed keeping incremental processing firmly in mind. It was written about three years ago and in constant use. The program runs for days and indeed moves quite large amount of data to and from the database (the amount of data in a transaction can be larger than the amount of available memory).

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ANN: atom-0.0.2
by Tom Hawkins 05 May '09

05 May '09

Atom is a DSL in Haskell for designed hard realtime embedded programs. At Eaton, we are using it to control hydraulic hybrid refuse trucks and shuttle buses. After my talk at CUFP (http://cufp.galois.com/2008/schedule.html) a few people inquired about atom -- I finally had a chance to upload it to Hackage. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/atom-0.0.2 Some new enhancements: - A simple rule scheduler for load balancing. - Signal probing for debug and data logging. - Functional coverage to monitor which rules have executed. - Started integration with the Yices SMT solver for bounded model checking. Experiences with our Eaton project: - 5K lines of Haskell/atom replaced 120K lines of matlab, simulink, and visual basic. - 2 months to port simulink design to atom. - 3K lines of atom generates 22K lines of embedded C. - Design composed of 450 atomic state transition rules. - Rules with execution periods from 1ms to 10s all scheduled at compile time to a 1 ms main loop. - 3 minute compilation time from atom source to ECU. - Atom design clears electronic/sw testing on first pass. - Currently in vehicle testing with no major issues. Tom

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Using Takusen is a real intellectual challenge
by Gü?nther Schmidt 05 May '09

05 May '09

Hi, well I'm *trying* to use Takusen to export from one database into the other. I'm using Takusen for this so that I can guarantee that during the export not a single huge result is assembled (possibly in memory) and then insert in one lump into the second database. Trying to figure out how to do that in Takusen has left me totally exhausted, my brain is pudding and I need to have a lay down now. I couldn't even figure out whether that's at all possible. help Günther

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Odd error message from ghc --make
by Jeff Heard 04 May '09

04 May '09

I was just running a test that has compiled before just fine, and now I'm getting this rather odd message: EventBusTest.hs:20:9: Couldn't match expected type `Bus a' against inferred type `buster-1.1:App.EventBus.Bus [buster-1.1:App.EventBus.EData a1]' Expected type: MVar (Bus a) Inferred type: MVar (buster-1.1:App.EventBus.Bus [buster-1.1:App.EventBus.EData a1]) In the expression: mk In the first argument of `bus', namely `[mk]' Any ideas? I mean, it looks like it type checks to me.

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Re: [Haskell-cafe] HDBC 2.1, UTF8 and Umlauts
by John Goerzen 04 May '09

04 May '09

Guenther Schmidt wrote: > Hi John, > > thanks for taking the time. It actually is \252 that turned into > something else because of my email client, damn the thing. OK, perhaps we have some confusion here. Are you saying that you entered the Unicode characters directly into your Haskell source as literals? In other words, you did not type: backslash two five two but instead just typed the umlaut on the keyboard? If so, that won't work directly -- I think. Maybe somebody can correct me on this, but my hunch is that would save the umlaut as UTF-8 when you save the .hs file. Then you will get a String which is supposed to have decoded Unicode data, instead having encoded UTF-8 data. You could wrap it with Codec.Binary.UTF8.String.decodeString from utf8-string and see if that helps. If it does, that'll be your problem. It's a complicated topic, I know. And the scary thing is that Unicode makes this all *easier*. > > I'll do some further investigating and give you some more details when I > have them, thanks in advance. > > Günther > > > John Goerzen schrieb: >> On Mon, May 04, 2009 at 04:44:04PM +0200, Guenther Schmidt wrote: >> >>> Hi John, >>> >>> I'm trying stuff like: >>> >>> dbc <- connectSqlite3 "somedatabase" >>> run dbc "insert into someTable values (?)" [toSql "Günni"]. >>> >> SO what do you get back after adding: >> >> commit >> r <- quickQuery' dbc "select * from someTable" >> print r >> >> Just knowing it's garbled doesn't help. Need to know *how* it's >> garbled. >> >> But the problem is that \374 isn't Unicode at all. It's ISO-8859-1. >> You're not actually giving it Unicode data to start with. I believe >> the proper sequence is \252. >> >> For all I know, \374 may not even be a valid Unicode encoding (haven't >> tested it). >> >> Try \252. >> >> >> >>> I also tried: >>> >>> dbc <- connectSqlite3 "somedatabase" >>> run dbc "insert into someTable values ('Günni')" []. >>> >>> So since this is Haskell code I presume it's in UTF-8, my emacs stores >>> all my *.hs files as UTF-8 >>> >>> In either case the "ü" becomes garbled. >>> >>> With the previous version of HDBC, 1.1.6, this worked just fine. >>> >>> >>> It also garbles any Umlauts coming *out*, the source is an UTF-8 sqlite3 >>> db file. >>> >>> Günther >>> >>> >>> >>> John Goerzen schrieb: >>> >>>> GüŸnther Schmidt wrote: >>>> >>>> >>>>> Hi guys, >>>>> >>>>> for some reason, any way I try, all the Umlauts get garbled with HDBC 2.1. >>>>> HDBC 1.16 worked fine with any backend (ODBC, Sqlite3, ... what have you). >>>>> >>>>> Anybody else had similar problems and knows how to solve this? >>>>> >>>>> >>>> You need to be more specific, but it is likely you are trying to send >>>> something to HDBC that isn't encoded in UTF-8. HDBC 2.x has a global >>>> preference for UTF-8 now, actually partly to resolve complaints like this. >>>> >>>> If you are feeding it ISO-8859-1 data or somesuch, try giving it UTF-8 >>>> instead. >>>> >>>> -- John >>>> >>>> >>> > > >

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Darcs and binary files
by Gü?nther Schmidt 04 May '09

04 May '09

Hi, I've gotten used to darcs now, and use it for my project. There is one quirk though, I also added some rather large binary files, an sqlite database and an MS Access database to the repository. Now whenever I do a push from a branch into the main trunk the system runs out of memory. Guess I should have left the binary files out of there? Günther

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Re: [Haskell-cafe] HDBC 2.1, UTF8 and Umlauts
by John Goerzen 04 May '09

04 May '09

Günther Schmidt wrote: > Am 04.05.2009 um 21:07 schrieb John Goerzen: > >> Günther Schmidt wrote: >>> Hi John, >>> >>> I'm afraid so. >>> >>> If it came back as an SqlString "G\252nni" then it propably wouldn't >>> be a problem. >> Can you boil this down to a few-line self-contained test program so I >> can try it myself? I do have test cases for Unicode stuff and they >> are >> all passing here. I would like to be able to eliminate your >> environment >> as a culprit. >> > I'll try, it will take me some time since I've never written a test in > haskell. You don't really have to make a special unit test. Just a simple client program that creates a table, inserts some data, reads it back, and demonstrates the corruption. > That'll be harder to do since I'm on XP here, but I'll try that too, No problem. It's just runghc setup configure -f buildtests runghc setup build and just run runtests >>> >>> >>> >>> Am 04.05.2009 um 20:47 schrieb John Goerzen: >>> >>>> Günther Schmidt wrote: >>>>> Hi John, >>>>> >>>>> what I just noticed is that *all* strings come back as >>>>> SqlByteStrings. >>>> That's normal, and pretty much irrelevant, since fromSql takes care >>>> of it. >>>> >>>> It's documented, even: the SqlByteString is assumed to be in UTF-8, >>>> and >>>> is decoded when converted to a String. >>>> >>>> It is not correct to have \252 in the SqlByteString. The proper >>>> sequence there is \xc3\xbc. When converted to String, *then* it >>>> should >>>> be \252. >>>> >>>> Are you positive you're seeing \252 in the SqlByteString? That >>>> doesn't >>>> make any sense to me. It's not a valid UTF-8 encoding. >>>> >>> How have Umlauts been behaving on your end? Were they as mean to you >>> as they were to me? >>> >>> >>> >>>>> ie. I get my "Günni", (G\252nni), back as an SqlByteString "G >>>>> \252nni" >>>>> instead of an SqlString "G\252nni". >>>>> >>>>> So when I cast, ie. fromSql x :: String, I get an "G\65533nni", >>>>> which >>>>> is where the garbling occurs. >>>>> >>>>> >>>>> BTW this is the 3rd time now that I'm writing the same bloody >>>>> email, >>>>> my email client "clipped" the previous 2. >>>>> >>>>> Günther >>>>> >>>>> >>> > >

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