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database error simply by using a sting in a variable
by Damien Mattei 05 Dec '18

05 Dec '18

why i'm getting this error? code: let name = "'A 20'" let qry = "select `N° BD` from Coordonnées where Nom = " ++ name putStrLn qry bd_rows <- query_ conn qry putStrLn $ show bd_rows putStrLn $ show name forM_ bd_rows $ \(Only a) -> putStrLn $ Text.unpack a error: *Main> :load UpdateSidonie [1 of 1] Compiling Main ( UpdateSidonie.hs, interpreted ) UpdateSidonie.hs:74:28: error: • Couldn't match expected type ‘Query’ with actual type ‘[Char]’ • In the second argument of ‘query_’, namely ‘qry’ In a stmt of a 'do' block: bd_rows <- query_ conn qry In the expression: do conn <- connect defaultConnectInfo {connectHost = "moita", connectUser = "mattei", connectPassword = "sidonie2", connectDatabase = "sidonie"} rows <- query_ conn "SELECT Nom,distance FROM AngularDistance WHERE distance > 0.000278" forM_ rows $ \ (name, distance) -> putStrLn $ unpack name ++ " " ++ show (distance :: Double) let name = "'A 20'" .... | 74 | bd_rows <- query_ conn qry | ^^^ Failed, no modules loaded. -- Damien.Mattei(a)unice.fr, Damien.Mattei(a)oca.eu, UNS / OCA / CNRS

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Database simple-mysql
by Damien Mattei 05 Dec '18

05 Dec '18

why does this works: let name = "'A 20'" bd_rows <- query_ conn "select `N° BD` from sidonie.Coordonnées where Nom = 'A 20'" putStrLn $ show bd_rows putStrLn $ show name i got: [Only {fromOnly = "-04.3982"}] "'A 20'" -04.3982 but not with this: bd_rows <- query conn "select `N° BD` from sidonie.Coordonnées where Nom = ?" (Only (name::String)) i got an empty result: [] ... ??? -- Damien.Mattei(a)unice.fr, Damien.Mattei(a)oca.eu, UNS / OCA / CNRS

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About Installing Sqlite3, HDBC and convertible
by Eyüp Kaan AKAY 05 Dec '18

05 Dec '18

Hi. I want to use sqlite3. When I work to install it, I got this error: hdbc-sqlite3-master$ ghc --make -o setup Setup.lhs hdbc-sqlite3-master$ ghc --make -o setup Setup.hs [1 of 1] Compiling Main ( Setup.hs, Setup.o ) Linking setup ... hdbc-sqlite3-master$ ./setup configure Configuring HDBC-sqlite3-2.3.3.1... setup: At least the following dependencies are missing: HDBC >=2.3.0.0, utf8-string -any When I want to install HDBC, I got this error: HDBC-2.4.0.2$ ghc --make -o setup Setup.lhs HDBC-2.4.0.2$ ./setup configure Configuring HDBC-2.4.0.2... setup: At least the following dependencies are missing: convertible >=1.1.0.0, utf8-string -any Then I install convertible and I got any errors then first I work to install HDBC but I got the same error. So what can I do else?

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database access,extracting result...
by Damien Mattei 04 Dec '18

04 Dec '18

{-# LANGUAGE OverloadedStrings #-} import Database.MySQL.Simple import Control.Monad import Data.Text as Text import Data.Int main :: IO () main = do conn <- connect defaultConnectInfo { connectHost = "moita", connectUser = "mattei", connectPassword = "******", connectDatabase = "sidonie" } rows <- query_ conn "select `N° BD` from sidonie.Coordonnées where Nom = 'A 20'" --putStrLn $ show rows forM_ rows $ \(fname, lname) -> putStrLn $ fname ++ " " ++ Text.unpack lname ++ " " here is the error: *Main> :load Toto [1 of 1] Compiling Main ( Toto.hs, interpreted ) Ok, one module loaded. *Main> main *** Exception: ConversionFailed {errSQLType = "1 values: [(VarString,Just \"-04.3982\")]", errHaskellType = "2 slots in target type", errFieldName = "[\"N\\194\\176 BD\"]", errMessage = "mismatch between number of columns to convert and number in target type"} -04.3982 is the values i want to put in a variable,it's the N° BD (Durchmusterung Number) ??? any help greatly appeciated ;-) -- Damien.Mattei(a)unice.fr, Damien.Mattei(a)oca.eu, UNS / OCA / CNRS

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how to debug Prelude.read: no parse
by PICCA Frederic-Emmanuel 21 Nov '18

21 Nov '18

Hello, I am using the soap package and wrote a StreamParser which use the Consuite Xml system I have this kind of error when I execute my code [picca@process2 autoprocess-exe]$ stack exec autoprocessing-exe -- exec --json \{\"tag\":\"XdsMe\",\"contents\":[39878,[0,0,0,0,22,0],null,\"UnCompressed\"]\} +RTS -xc -Pa response:<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"><soap:Body><ns2:findDataCollectionResponse xmlns:ns2="http://ispyb.ejb3.webservices.collection"><dataCollection><actualCenteringPosition> /omega=280.000125 /phi=0.000020 /uglidex=-1.403875 /phiz=-0.127760 /chi=0.000005 /uglidey=-0.508216 /zoom=646.972000</actualCenteringPosition><axisEnd>180.0</axisEnd><axisRange>0.1</axisRange><axisStart>0.0</axisStart><beamShape>rectangular</beamShape><beamSizeAtSampleX>100.0</beamSizeAtSampleX><beamSizeAtSampleY>100.0</beamSizeAtSampleY><dataCollectionId>39878</dataCollectionId><dataCollectionNumber>1</dataCollectionNumber><detector2theta>0.0</detector2theta><detectorDistance>296.869</detectorDistance><endTime>2018-11-21T16:54:18+01:00</endTime><exposureTime>0.025</exposureTime><fileTemplate>C2-BZ1692_1</fileTemplate><flux>1.27E10</flux><flux_end>1.27E10</flux_end><imageDirectory>/data4/proxima1-soleil/2018_Run5/2018-11-21/20180897/RAW_DATA/C2/C2-BZ1692</imageDirectory><imagePrefix>C2-BZ1692</imagePrefix><imageSuffix>h5</imageSuffix><kappaStart>0.0</kappaStart><numberOfImages>1800</numberOfImages><numberOfPasses>1</numberOfPasses><overlap>0.0</overlap><phiStart>0.0</phiStart><printableForReport>1</printableForReport><resolution>1.99996</resolution><rotationAxis>Phi</rotationAxis><runStatus>Data collection successful</runStatus><slitGapHorizontal>9999.0</slitGapHorizontal><slitGapVertical>9999.0</slitGapVertical><startImageNumber>1</startImageNumber><startTime>2018-11-21T16:52:42+01:00</startTime><synchrotronMode>Hybrid</synchrotronMode><transmission>20.1</transmission><undulatorGap1>6.4649</undulatorGap1><wavelength>0.978566</wavelength><xbeam>2044.1</xbeam><ybeam>2291.12</ybeam><dataCollectionGroupId>41587</dataCollectionGroupId></dataCollection></ns2:findDataCollectionResponse></soap:Body></soap:Envelope> *** Exception (reporting due to +RTS -xc): (THUNK_1_0), stack trace: Data.Conduit.Internal.Conduit.fmap.\, called from Data.Conduit.Internal.Conduit.fmap, called from Network.SOAP.Parsing.Stream.readContent, called from Network.SOAP.Parsing.Stream.readTag, called from ISPyB.Soap.toResponseParser, called from Data.Conduit.Internal.Conduit.pure, called from Data.Conduit.Internal.Conduit.>>=.\.\, called from Data.Conduit.Internal.Conduit.>>=.\, called from Data.Conduit.Internal.Conduit.>>=, called from Text.XML.Stream.Parse.force, called from Network.SOAP.unwrapEnvelopeSink, called from Network.SOAP.runResponseParser, called from Network.SOAP.invokeWS, called from ISPyB.Soap.callISPyBService, called from XdsMe.xdsme, called from JobParser.runJob, called from Main.run, called from Main.main autoprocessing-exe: Prelude.read: no parse CallStack (from -prof): Data.Conduit.Internal.Conduit.fmap.\ (src/Data/Conduit/Internal/Conduit.hs:140:47-58) Data.Conduit.Internal.Conduit.fmap (src/Data/Conduit/Internal/Conduit.hs:140:5-58) Network.SOAP.Parsing.Stream.readContent (src/Network/SOAP/Parsing/Stream.hs:57:1-46) Network.SOAP.Parsing.Stream.readTag (src/Network/SOAP/Parsing/Stream.hs:61:1-33) ISPyB.Soap.toResponseParser (src/ISPyB/Soap.hs:(65,5)-(129,74)) Data.Conduit.Internal.Conduit.pure (src/Data/Conduit/Internal/Conduit.hs:143:5-27) Data.Conduit.Internal.Conduit.>>=.\.\ (src/Data/Conduit/Internal/Conduit.hs:150:51-68) Data.Conduit.Internal.Conduit.>>=.\ (src/Data/Conduit/Internal/Conduit.hs:150:41-68) Data.Conduit.Internal.Conduit.>>= (src/Data/Conduit/Internal/Conduit.hs:150:5-68) Text.XML.Stream.Parse.force (Text/XML/Stream/Parse.hs:873:1-68) Network.SOAP.unwrapEnvelopeSink (src/Network/SOAP.hs:(79,1)-(81,30)) Network.SOAP.runResponseParser (src/Network/SOAP.hs:(61,1)-(76,31)) Network.SOAP.invokeWS (src/Network/SOAP.hs:(55,1)-(58,27)) ISPyB.Soap.callISPyBService (src/ISPyB/Soap.hs:(310,1)-(325,93)) XdsMe.xdsme (src/XdsMe.hs:(176,1)-(179,77)) JobParser.runJob (src/JobParser.hs:(80,1)-(84,57)) Main.run (app/Main.hs:(112,1)-(114,31)) Main.main (app/Main.hs:(118,1)-(123,72)) I generate the stacktrace with RTS. but now I know theat my error is in the roRespondParser whcih is quite long here the code instance a ~ b => ToResponseParser (ToolsForCollectionWebService a) b where toResponseParser (FindDataCollection _) = StreamParser . flaxTag "findDataCollectionResponse" . flaxTag "dataCollection" $ mkSomeDataCollection <$> ( DataCollection <$> flaxContent "actualCenteringPosition" <*> readTag "axisEnd" <*> readTag "axisRange" <*> readTag "axisStart" <*> flaxContent "beamShape" <*> readTag "beamSizeAtSampleX" <*> readTag "beamSizeAtSampleY" <*> laxTag "centeringMethod" readContent <*> (DataCollectionId <$> readTag "dataCollectionId") <*> readTag "dataCollectionNumber" <*> readTag "detector2theta" <*> readTag "detectorDistance" <*> flaxContent "endTime" <*> readTag "exposureTime" <*> flaxContent "fileTemplate" <*> readTag "flux" <*> readTag "flux_end" <*> flaxTag "imageDirectory" parseAbsDir' <*> flaxContent "imagePrefix" <*> laxContent "imageSuffix" <*> readTag "kappaStart" <*> readTag "numberOfImages" <*> readTag "numberOfPasses" <*> laxTag "omegaStart" readContent <*> readTag "overlap" <*> readTag "phiStart" <*> readTag "printableForReport" <*> readTag "resolution" <*> laxTag "resolutionAtCorner" readContent <*> readTag "rotationAxis" <*> flaxContent "runStatus" <*> readTag "slitGapHorizontal" <*> readTag "slitGapVertical" <*> readTag "startImageNumber" <*> readTag "startTime" <*> readTag "synchrotronMode" <*> readTag "transmission" <*> readTag "undulatorGap1" <*> laxTag "undulatorGap2" readContent <*> readTag "wavelength" -- add the unit <*> readTag "xbeam" <*> laxTag "xtalSnapshotFullPath1" parseAbsFile' <*> laxTag "xtalSnapshotFullPath2" parseAbsFile' <*> laxTag "xtalSnapshotFullPath3" parseAbsFile' <*> laxTag "xtalSnapshotFullPath4" parseAbsFile' <*> readTag "ybeam" <*> readTag "dataCollectionGroupId" ) Now I would like to know whcih line is problematic. Is it possible to have more information when debuging ? I really want to know which part of my response is wrong ? thansk for your advices. Frederic

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Re: [Haskell-beginners] Lifting over record syntax
by Anthony Clayden 31 Oct '18

31 Oct '18

Hi Jaakko, oh dear you've picked on the most embarrassing part of Haskell. > data Person = Person {name::String, age::Int} deriving Show > > Now, I can create maybe-people like in applicative style: > > Person <$> Just "John Doe" <*> Nothing Hmm? That returns Nothing -- is that what you expect? Perhaps Person <$> Just "John Doe" <*> Just undefined But why not Just $ Person "John Doe" undefined > The problem with the [applicative] approach > is that it depends on the order of the arguments > because it doesn't utilize the record syntax. You'd think that a leading-edge language like Haskell would have really powerful record abstractions. With ways to avoid the shackles of argument ordering. Then it's sad to admit Haskell's records are feeble. Back in Haskell 98 people were saying "surely we can do better!" Well, essentially nothing's happened. So records are no more than pretty(-ish?) syntax for the ordered arguments style. The label names are not first-class. And field labels for building records only work in very restricted syntactic positions, as you point out: > I would like to get the benefits of the the record syntax > but with similar code simplicity as the applicative style has. > Do you have ideas is this possible? > My non-working pseudo-code would look like: > > Person <$> {name=Just "John Doe", age=Nothing} > > But this doesn't work, it's syntax error. You want that bit in braces to be a free-standing expression. That's called "anonymous/extensible records" (search Haskell wiki). "Anonymous" because it's not tied to any particular datatype. It's self-describing: I am a record with two fields labelled `name, age`; and the order of the labelled fields should be arbitrary. "Extensible" because you could start a record with just one labelled field, and extend it with another labelled field. But I'm not sure what the `Maybe` wrapping is doing for you? I'm going to ignore it. I have some good news and some bad news. There is a Haskell you can do n = (name = "John Doe") -- note round parens n_a = (age = undefined | n) -- | for extend the record p = Person n_a For that you need a slightly different data decl data Person = Person (Rec (name :: String, age :: Int)) deriving Show Round parens again; and a mysterious type constructor. But these records are first-class values. (They're a special variety of tuples.) Perhaps you don't need a datatype? type Person = Rec (name :: String, age :: Int) Then you don't need to apply a data constructor. This style of records is 'Trex' -- Typed Records with extensibility https://www.haskell.org/hugs/pages/hugsman/exts.html#sect7.2 The bad news: Trex is available only in a very old Haskell system, Hugs. So old that its download has bitrotted, see note here https://mail.haskell.org/pipermail/hugs-bugs/2018-July/001914.html GHC has had 12 years to come up with something comparable/better. So far, nothing. If you're wanting to get all Applicative and Functorial in GHC, there are heaps of record systems based around Lenses. http://hackage.haskell.org/package/lens-tutorial But that's going way beyond Beginners level; you'll need to call on Template Haskell; and probably add some plumbing of your own. (And under the hood you still have ordered arguments; they're rather better encapsulated.) AntC

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Tagged types
by PICCA Frederic-Emmanuel 29 Oct '18

29 Oct '18

Hello suppose that I have a bunch of type like this data Unchecked data Hdf5 data Cbf data A t > A String The A thing come from a database as A Unchecked now if I read the String and it ends with .h5, I have a A Hdf5 type and If the string end with .cbf, I have a A Cbf. So I would like a function which allow to return a A Hdf5 or a A Cbf depending on the String content. check :: A Unchecked -> A ??? check = ??? Is it possible to do this ? Thanks Frederic PS: At the end I will have more tha one tag.

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I can't start WinGHCi Haskell
by Gustavo Arturo Marquez Flores 14 Oct '18

14 Oct '18

Hi, I want to start with Haskell language programming. But when I launch the WinGHCi program I got he followin message: [image: image.png] What can I do ? How to resolve this problem ? I use Windows 10 plataform. I aprecite your help for resolving this problem to me. Thanks a lot.

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Lifting over record syntax
by Jaakko Luttinen 14 Oct '18

14 Oct '18

Hi! Let's consider this simple data structure: data Person = Person {name::String, age::Int} deriving Show Now, I can create maybe-people like in applicative style: Person <$> Just "John Doe" <*> Nothing or in monad style: do name' <- Just "John Doe" age' <- Nothing return Person {name=name', age=age'} The problem with the first approach is that it depends on the order of the arguments because it doesn't utilize the record syntax. The problem with the second approach is that there's a bit of unnecessary boilerplate (e.g., name' and age' variables). I would like to get the benefits of the the record syntax but with similar code simplicity as the applicative style has. Do you have ideas is this possible? My non-working pseudo-code would look like: Person <$> {name=Just "John Doe", age=Nothing} But this doesn't work, it's syntax error. Any ideas for a nice syntax? Cheers, Jaakko

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why is ScopedTypeVariables not fixing this error?
by Dennis Raddle 09 Oct '18

09 Oct '18

In the following snippet from a program in progress (designed to compute percentile rank for arbitrary lists of values) , I was hoping to declare types of functions within the main function just as a way of helping myself catch type errors. I'm getting the error "Can't match 'a' with 'a1'.... where 'a' is rigid type variable... etc. etc." on the line indicated in the comment below. The usual error I get when I try to do this without ScopedTypeVariables. So, I thought that ScopedTypeVariables was supposed to allow this kind of usage. What am I doing wrong? {-# LANGUAGE ScopedTypeVariables #-} import qualified Data.Map as M import qualified Data.List as L import Data.Map(Map) import Data.Function -- <percent at or below> <percent below> data PercentileData = PercentileData Double Double -- new attempt, October 2018: using new PercentileData construct to -- represent percentile in both ways. (at/below, or below) computePercentile :: Ord a => Map a Double -> Map a PercentileData computePercentile dataIn = error "foo" where pairs :: [(a,Double)] -- THIS IS THE LINE GETTING THE ERROR pairs = L.sortBy (compare `on` snd) $ M.toList dataIn

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