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  • Need advice to choose correct wi-fi drivers for Dell Vostro 3560

    - by overdriven
    I'm having problems with my Dell notebook's Wi-Fi, it can't see some of the available access points, despite they are close and I used to be connected to them yesterday. Other notebooks and my phone can see them. I believe it's a driver issue, since after installing system I haven't downloaded any network drivers. I went to Dell's website to search for them but I have no idea which should I choose. For my Dell Vostro 3560 and system Windows 8.1 64bit these are available: Intel Smart Connect Technology Application APP_iSCT_W8.1_A00_Setup-TJW84_ZPE.exe (23 MB) Vostro-3560_Network_Application_TJW84_WN_4.2.40.2418_A00.EXE (29 MB) Dell Wireless 1704 WLAN 802.11b/g/n (2.4GHz), Bluetooth v4.0+HS Driver DW1704_W8.1_A00_Setup-K1HGN_ZPE.exe (239 MB) Network_Driver_K1HGN_WN_6.30.223.143_A00.EXE (247 MB) Dell Wireless1703 802.11 b/g/n, BT4.0 + HS Driver Dell Wireless1901 802.11a/b/g/n (2.4GHz and 5GHz), Bluetooth v4.0+HS Driver DW1703_DW1901_Win8.1_A00_Setup-7FPWR_ZPE.exe (265 MB) Network_Driver_7FPWR_WN_10.0.0.263_A00.EXE (272 MB) Realtek RTL8105E/RTL8111E Ethernet Controller Driver LOM_Realtek_W8.1_A00_Setup-0XCVW_ZPE.exe (6 MB) Network_Driver_0XCVW_WN_8.018.0621.2013_A00.EXE (12 MB) Intel® Centrino® Wireless-N 2230 Bluetooth Driver BT_Intel_W8.14_A00_Setup-XR83W_ZPE.exe (31 MB) Network_Application_XR83W_WN_3.1.1307.0362_A00.EXE (37 MB)

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  • Best practices on using URIs as parameter value in REST calls.

    - by dafmetal
    I am designing a REST API where some resources can be filtered through query parameters. In some cases, these filter values would be resources from the same REST API. This makes for longish and pretty unreadable URIs. While this is not too much of a problem in itself because the URIs are meant to be created and manipulated programmatically, it makes for some painful debugging. I was thinking of allowing shortcuts to URIs used as filter values and I wonder if this is allowed according to the REST architecture and if there are any best practices. For example: I have a resource that gets me Java classes. Then the following request would give me all Java classes: GET http://example.org/api/v1/class Suppose I want all subclasses of the Collection Java class, then I would use the following request: GET http://example.org/api/v1/class?has-supertype=http://example.org/api/v1/class/collection That request would return me Vector, ArrayList and all other subclasses of the Collection Java class. That URI is quite long though. I could already shorten it by allowing hs as an alias for has-supertype. This would give me: GET http://example.org/api/v1/class?hs=http://example.org/api/v1/class/collection Another way to allow shorter URIs would be to allow aliases for URI prefixes. For example, I could define class as an alias for the URI prefix http://example.org/api/v1/class/. Which would give me the following possibility: GET http://example.org/api/v1/class?hs=class:collection Another possibility would be to remove the class alias entirely and always prefix the parameter value with http://example.org/api/v1/class/ as this is the only thing I would support. This would turn the request for all subtypes of Collection into: GET http://example.org/api/v1/class?hs=collection Do these "simplifications" of the original request URI still conform to the principles of a REST architecture? Or did I just go off the deep end?

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  • Beginning Haskell: "not in scope" Unprecedented error

    - by user1071838
    So I just started learning Haskell, and this (http://learnyouahaskell.com) nifty book is giving a lot of help. So yesterday I wrote in a text file doubleMe x = x + x and saved it as double.hs. So after saving that I open up my command prompt, CD to the right folder, type in "ghci" to get haskell started, and then type in >doubleMe 5 10 and everything seems to work. Now today, I do the same thing and this happens (actual copy paste from command line) . . . C:\Users\myName\haskell>ghci GHCi, version 7.0.3: http://www.haskell.org/ghc/ :? for help Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. Loading package base ... linking ... done. Loading package ffi-1.0 ... linking ... done. Prelude> :l double.hs [1 of 1] Compiling Main ( double.hs, interpreted ) Ok, modules loaded: Main. *Main> doubleMe 5 <interactive>:1:1: Not in scope: `doubleMe' So basically, everything was working fine, but now haskell can't find the function I wrote in double.hs. Can anyone tell what is going on? I'm pretty lost and confused. This is just a guess but does it have to do with *Main at all? Thanks for the help.

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  • Safe and polymorphic toEnum

    - by jetxee
    I'd like to write a safe version of toEnum: safeToEnum :: (Enum t, Bounded t) => Int -> Maybe t A naive implementation: safeToEnum :: (Enum t, Bounded t) => Int -> Maybe t safeToEnum i = if (i >= fromEnum (minBound :: t)) && (i <= fromEnum (maxBound :: t)) then Just . toEnum $ i else Nothing main = do print $ (safeToEnum 1 :: Maybe Bool) print $ (safeToEnum 2 :: Maybe Bool) And it doesn't work: safeToEnum.hs:3:21: Could not deduce (Bounded t1) from the context () arising from a use of `minBound' at safeToEnum.hs:3:21-28 Possible fix: add (Bounded t1) to the context of an expression type signature In the first argument of `fromEnum', namely `(minBound :: t)' In the second argument of `(>=)', namely `fromEnum (minBound :: t)' In the first argument of `(&&)', namely `(i >= fromEnum (minBound :: t))' safeToEnum.hs:3:56: Could not deduce (Bounded t1) from the context () arising from a use of `maxBound' at safeToEnum.hs:3:56-63 Possible fix: add (Bounded t1) to the context of an expression type signature In the first argument of `fromEnum', namely `(maxBound :: t)' In the second argument of `(<=)', namely `fromEnum (maxBound :: t)' In the second argument of `(&&)', namely `(i <= fromEnum (maxBound :: t))' As well as I understand the message, the compiler does not recognize that minBound and maxBound should produce exactly the same type as in the result type of safeToEnum inspite of the explicit type declaration (:: t). Any idea how to fix it?

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  • Existentials and Scrap your Boilerplate

    - by finnsson
    I'm writing a XML (de)serializer using Text.XML.Light and Scrap your Boilerplate (at http://github.com/finnsson/Text.XML.Generic) and so far I got working code for "normal" ADTs but I'm stuck at deserializing existentials. I got the existential data type data DataBox where DataBox :: (Show d, Eq d, Data d) => d -> DataBox and I'm trying to get this to compile instance Data DataBox where gfoldl k z (DataBox d) = z DataBox `k` d gunfold k z c = k (z DataBox) -- not OK toConstr (DataBox d) = toConstr d dataTypeOf (DataBox d) = dataTypeOf d but I can't figure out how to implement gunfold for DataBox. The error message is Text/XML/Generic.hs:274:23: Ambiguous type variable `b' in the constraints: `Eq b' arising from a use of `DataBox' at Text/XML/Generic.hs:274:23-29 `Show b' arising from a use of `DataBox' at Text/XML/Generic.hs:274:23-29 `Data b' arising from a use of `k' at Text/XML/Generic.hs:274:18-30 Probable fix: add a type signature that fixes these type variable(s) It's complaining about not being able to figure out the data type of b. I'm also trying to implement dataCast1 and dataCast2 but I think I can live without them (i.e. an incorrect implementation). I guess my questions are: Is it possible to combine existentials with Scrap your Boilerplate? If so: how do you implement gunfold for an existential data type?

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  • GADTs and Scrap your Boilerplate

    - by finnsson
    I'm writing a XML (de)serializer using Text.XML.Light and Scrap your Boilerplate (at http://github.com/finnsson/Text.XML.Generic) and so far I got working code for "normal" ADTs but I'm stuck at deserializing GADTs. I got the GADT data DataBox where DataBox :: (Show d, Eq d, Data d) => d -> DataBox and I'm trying to get this to compile instance Data DataBox where gfoldl k z (DataBox d) = z DataBox `k` d gunfold k z c = k (z DataBox) -- not OK toConstr (DataBox d) = toConstr d dataTypeOf (DataBox d) = dataTypeOf d but I can't figure out how to implement gunfold for DataBox. The error message is Text/XML/Generic.hs:274:23: Ambiguous type variable `b' in the constraints: `Eq b' arising from a use of `DataBox' at Text/XML/Generic.hs:274:23-29 `Show b' arising from a use of `DataBox' at Text/XML/Generic.hs:274:23-29 `Data b' arising from a use of `k' at Text/XML/Generic.hs:274:18-30 Probable fix: add a type signature that fixes these type variable(s) It's complaining about not being able to figure out the data type of b. I'm also trying to implement dataCast1 and dataCast2 but I think I can live without them (i.e. an incorrect implementation). I guess my questions are: Is it possible to combine GADTs with Scrap your Boilerplate? If so: how do you implement gunfold for a GADT?

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  • Buffalo TeraStation Firmware Upgrade

    - by jason
    Hi All, I was given a TeraStation HS-DH0.0TGL/R5 It came to me working with 4x250gb. I added 4 x 1TB, TFTP booted and data was copied. How do I load firmware and software now to get it running? I was going based upon this article: http://forums.buffalotech.com/t5/Storage/FAQ-3-of-3-TFTP-boot-procedure-please-read-this/m-p/11015 I downloaded TFTP Boot Recovery HS-DHTGL-R5 2.13.exe and Terastation_112-104.zip Advice is appreciated.

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  • What if you used the wrong language?

    - by HS
    A reply to another question made me remember a project from some years ago when it turned out that Java was not the right tool to use. I typically only learn a new language when I have a problem that it solves better than the ones I already know. [...] Then I write whatever program I wanted to learn that language for in the first place. [...] By the time I've gotten my target program written, I've usually got a decent handle on the language, not to mention any other features it has, and I've got other ideas to use it for. I did just that back then with Java, because the client thought it to be the right language to use (platform independent) and initial evaluation confirmed that. However, much later in the project there were some issue (can't really remember all the details by now). So, the project that started as a nice learning experience turned into a nightmare toward the end. I was at the brink of switching over to my trusted C++ and doing a complete rewrite. The client was not so much of a problem to convince back then, but my supervisor was strongly opposed because of all the work that already went into the Java version. In hindsight, he was right and the project was complete more or less with the intended features kind of working, but it was the project that I am least proud of by now. Long story short: what do you think, when is it too much and the switch to another technology is worthwhile? I personally would estimate the point of no return to be around 50% of the planned effort, but really want to know, if anyone has real experience with such a switch. And to answer the inevitable question: I do not really care, if the technology switched to is proven or another new thing. The latter would basically need more initial scrutiny based on the past experiences in the problematic project.

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  • ghc can't find my cabal installed packages

    - by nont
    I've installed ghc 6.12.3, and then the Haskell Platform. I'm trying to compile a test program: $ ghc test.hs test.hs:3:0: Failed to load interface for `Bindings': Use -v to see a list of the files searched for. so, naturally, I do cabal install Bindings Which works fine, and places the package in ~/.cabal/lib/bindings-0.1.2 The problem is, that when I go to compile again with ghc, it still doesn't find the package I've installed with cabal. compiling in verbose mode gives: ghc -v test.hs Using binary package database: /home/ludflu/ghc/lib/ghc-6.12.3/package.conf.d/package.cache Using binary package database: /home/ludflu/.ghc/x86_64-linux 6.12.3/package.conf.d/package.cache As suggested by another stackoverflow user, I tried: ghc-pkg describe rts > rts.pkg vi rts.pkg # add the /home/ludflu/.cabal/lib to `library-dirs` field ghc-pkg update rts.pkg But to no avail. How to I add the .cabal to the list of package directories to search? Thank you!

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  • Java: calculate linenumber from charwise position according to the number of "\n"

    - by HH
    I know charwise positions of matches like 1 3 7 8. I need to know their corresponding line number. Example: file.txt Match: X Mathes: 1 3 7 8. Want: 1 2 4 4 $ cat file.txt X2 X 4 56XX [Added: does not notice many linewise matches, there is probably easier way to do it with stacks] $ java testt 1 2 4 $ cat testt.java import java.io.*; import java.util.*; public class testt { public static String data ="X2\nX\n4\n56XX"; public static String[] ar = data.split("\n"); public static void main(String[] args){ HashSet<Integer> hs = new HashSet<Integer>(); Integer numb = 1; for(String s : ar){ if(s.contains("X")){ hs.add(numb); numb++; }else{ numb++; } } for (Integer i : hs){ System.out.println(i); } } }

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  • Ubuntu "No space left on device" for /home, df shows 100% full, ds shows much, much less

    - by Jon Cram
    On an Ubuntu 12.04 server, normal users can no longer create or add to files in /home, encountering a "No space left on device" error. The /home directory has a capacity of 1.7 terabytes and as far as I can tell is nowhere near full in terms of actual data stored or inodes used. df -h shows: Filesystem Size Used Avail Use% Mounted on /dev/md2 1.0T 18G 955G 2% / udev 7.7G 4.0K 7.7G 1% /dev tmpfs 3.1G 320K 3.1G 1% /run none 5.0M 0 5.0M 0% /run/lock none 7.7G 0 7.7G 0% /run/shm cgroup 7.7G 0 7.7G 0% /sys/fs/cgroup /dev/md3 1.7T 1.7T 0 100% /home /dev/md1 496M 45M 426M 10% /boot /home indeed looks rather full. du -hs /home suggests otherwise: 1.4G /home There appears no inode issue - df -i: Filesystem Inodes IUsed IFree IUse% Mounted on /dev/md2 67108864 75334 67033530 1% / udev 2013497 527 2012970 1% /dev tmpfs 2015816 440 2015376 1% /run none 2015816 2 2015814 1% /run/lock none 2015816 1 2015815 1% /run/shm cgroup 2015816 9 2015807 1% /sys/fs/cgroup /dev/md3 113909760 105981 113803779 1% /home /dev/md1 131072 239 130833 1% /boot I recently deleted a many gigabytes of application cache and log data from /home, however this was in the tens of gigabytes at best and nowhere near the capcity of /home. Update 1: du -hs --apparent-size /home 1.2G /home du -hs /home 1.4G /home What might be going on here?

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  • Haskell: Gluing a char and a list together?

    - by Vincent
    So I have this code here: toWords :: String - [a] toWords "" = [] toWords (nr1 : rest) | nr1 == ' ' = toWords rest | otherwise = nr1 : toWords rest The "toWords" function should simply remove all spaces and return a list with all the words. But I keep getting this error: test.hs:5:18: Couldn't match expected type a' against inferred typeChar' `a' is a rigid type variable bound by the type signature for `toWords' at test.hs:1:22 In the first argument of `(:)', namely `nr1' In the expression: nr1 : toWords rest In the definition of `toWords': toWords (nr1 : rest) | nr1 == ' ' = toWords rest | otherwise = nr1 : toWords rest Failed, modules loaded: none.

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  • Couldn't match expected type - Haskell Code

    - by wvyar
    I'm trying to learn Haskell, but the small bit of sample code I tried to write is running into a fairly large amount of "Couldn't match expected type" errors. Can anyone give me some guidance as to what I'm doing wrong/how I should go about this? These are the errors, but I'm not really sure how I should be writing my code. toDoSchedulerSimple.hs:6:14: Couldn't match expected type `[t0]' with actual type `IO String' In the return type of a call of `readFile' In a stmt of a 'do' block: f <- readFile inFile In the expression: do { f <- readFile inFile; lines f } toDoSchedulerSimple.hs:27:9: Couldn't match expected type `[a0]' with actual type `IO ()' In the return type of a call of `putStr' In a stmt of a 'do' block: putStr "Enter task name: " In the expression: do { putStr "Enter task name: "; task <- getLine; return inFileArray : task } toDoSchedulerSimple.hs:34:9: Couldn't match expected type `IO ()' with actual type `[a0]' In a stmt of a 'do' block: putStrLn "Your task is: " ++ (inFileArray !! i) In the expression: do { i <- randomRIO (0, (length inFileArray - 1)); putStrLn "Your task is: " ++ (inFileArray !! i) } In an equation for `getTask': getTask inFileArray = do { i <- randomRIO (0, (length inFileArray - 1)); putStrLn "Your task is: " ++ (inFileArray !! i) } toDoSchedulerSimple.hs:41:9: Couldn't match expected type `[a0]' with actual type `IO ()' In the return type of a call of `putStr' In a stmt of a 'do' block: putStr "Enter the task you would like to end: " In the expression: do { putStr "Enter the task you would like to end: "; task <- getLine; filter (endTaskCheck task) inFileArray } toDoSchedulerSimple.hs:60:53: Couldn't match expected type `IO ()' with actual type `[String] -> IO ()' In a stmt of a 'do' block: schedulerSimpleMain In the expression: do { (getTask inFileArray); schedulerSimpleMain } In a case alternative: "get-task" -> do { (getTask inFileArray); schedulerSimpleMain } This is the code itself. I think it's fairly straightforward, but the idea is to run a loop, take input, and perform actions based off of it by calling other functions. import System.Random (randomRIO) import Data.List (lines) initializeFile :: [char] -> [String] initializeFile inFile = do f <- readFile inFile let parsedFile = lines f return parsedFile displayHelp :: IO() displayHelp = do putStrLn "Welcome to To Do Scheduler Simple, written in Haskell." putStrLn "Here are some commands you might find useful:" putStrLn " 'help' : Display this menu." putStrLn " 'quit' : Exit the program." putStrLn " 'new-task' : Create a new task." putStrLn " 'get-task' : Randomly select a task." putStrLn " 'end-task' : Mark a task as finished." putStrLn " 'view-tasks' : View all of your tasks." quit :: IO() quit = do putStrLn "We're very sad to see you go...:(" putStrLn "Come back soon!" createTask :: [String] -> [String] createTask inFileArray = do putStr "Enter task name: " task <- getLine return inFileArray:task getTask :: [String] -> IO() getTask inFileArray = do i <- randomRIO (0, (length inFileArray - 1)) putStrLn "Your task is: " ++ (inFileArray !! i) endTaskCheck :: String -> String -> Bool endTaskCheck str1 str2 = str1 /= str2 endTask :: [String] -> [String] endTask inFileArray = do putStr "Enter the task you would like to end: " task <- getLine return filter (endTaskCheck task) inFileArray viewTasks :: [String] -> IO() viewTasks inFileArray = case inFileArray of [] -> do putStrLn "\nEnd of tasks." _ -> do putStrLn (head inFileArray) viewTasks (tail inFileArray) schedulerSimpleMain :: [String] -> IO() schedulerSimpleMain inFileArray = do putStr "SchedulerSimple> " input <- getLine case input of "help" -> displayHelp "quit" -> quit "new-task" -> schedulerSimpleMain (createTask inFileArray) "get-task" -> do (getTask inFileArray); schedulerSimpleMain "end-task" -> schedulerSimpleMain (endTask inFileArray) "view-tasks" -> do (viewTasks inFileArray); schedulerSimpleMain _ -> do putStrLn "Invalid input."; schedulerSimpleMain main :: IO() main = do putStr "What is the name of the schedule? " sName <- getLine schedulerSimpleMain (initializeFile sName) Thanks, and apologies if this isn't the correct place to be asking such a question.

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  • Very slow guards in my monadic random implementation (haskell)

    - by danpriduha
    Hi! I was tried to write one random number generator implementation, based on number class. I also add there Monad and MonadPlus instance. What mean "MonadPlus" and why I add this instance? Because of I want to use guards like here: -- test.hs -- import RandomMonad import Control.Monad import System.Random x = Rand (randomR (1 ::Integer, 3)) ::Rand StdGen Integer y = do a <-x guard (a /=2) guard (a /=1) return a here comes RandomMonad.hs file contents: -- RandomMonad.hs -- module RandomMonad where import Control.Monad import System.Random import Data.List data RandomGen g => Rand g a = Rand (g ->(a,g)) | RandZero instance (Show g, RandomGen g) => Monad (Rand g) where return x = Rand (\g ->(x,g)) (RandZero)>>= _ = RandZero (Rand argTransformer)>>=(parametricRandom) = Rand funTransformer where funTransformer g | isZero x = funTransformer g1 | otherwise = (getRandom x g1,getGen x g1) where x = parametricRandom val (val,g1) = argTransformer g isZero RandZero = True isZero _ = False instance (Show g, RandomGen g) => MonadPlus (Rand g) where mzero = RandZero RandZero `mplus` x = x x `mplus` RandZero = x x `mplus` y = x getRandom :: RandomGen g => Rand g a ->g ->a getRandom (Rand f) g = (fst (f g)) getGen :: RandomGen g => Rand g a ->g -> g getGen (Rand f) g = snd (f g) when I run ghci interpreter, and give following command getRandom y (mkStdGen 2000000000) I can see memory overflow on my computer (1G). It's not expected, and if I delete one guard, it works very fast. Why in this case it works too slow? What I do wrong?

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  • Excessive use of Inner Join for more than 3 tables

    - by Archangel08
    Good Day, I have 4 tables on my DB (not the actual name but almost similar) which are the ff: employee,education,employment_history,referrence employee_id is the name of the foreign key from employee table. Here's the example (not actual) data: **Employee** ID Name Birthday Gender Email 1 John Smith 08-15-2014 Male [email protected] 2 Jane Doe 00-00-0000 Female [email protected] 3 John Doe 00-00-0000 Male [email protected] **Education** Employee_ID Primary Secondary Vocation 1 Westside School Westshore H.S SouthernBay College 2 Eastside School Eastshore H.S NorthernBay College 3 Northern School SouthernShore H.S WesternBay College **Employment_History** Employee_ID WorkOne StartDate Enddate 1 StarBean Cafe 12-31-2012 01-01-2013 2 Coffebucks Cafe 11-01-2012 11-02-2012 3 Latte Cafe 01-02-2013 04-05-2013 Referrence Employee_ID ReferrenceOne Address Contact 1 Abraham Lincoln Lincoln Memorial 0000000000 2 Frankie N. Stein Thunder St. 0000000000 3 Peter D. Pan Neverland Ave. 0000000000 NOTE: I've only included few columns though the rest are part of the query. And below are the codes I've been working on for 3 consecutive days: $sql=mysql_query("SELECT emp.id,emp.name,emp.birthday,emp.pob,emp.gender,emp.civil,emp.email,emp.contact,emp.address,emp.paddress,emp.citizenship,educ.employee_id,educ.elementary,educ.egrad,educ.highschool,educ.hgrad,educ.vocational,educ.vgrad,ems.employee_id,ems.workOne,ems.estartDate,ems.eendDate,ems.workTwo,ems.wstartDate,ems.wendDate,ems.workThree,ems.hstartDate,ems.hendDate FROM employee AS emp INNER JOIN education AS educ ON educ.employee_id='emp.id' INNER JOIN employment_history AS ems ON ems.employee_id='emp.id' INNER JOIN referrence AS ref ON ref.employee_id='emp.id' WHERE emp.id='$id'"); Is it okay to use INNER JOIN this way? Or should I modify my query to get the results that I wanted? I've also tried to use LEFT JOIN but still it doesn't return anything .I didn't know where did I go wrong. You see, as I have thought, I've been using the INNER JOIN in correct manner, (since it was placed before the WHILE CLAUSE). So I couldn't think of what could've possible went wrong. Do you guys have a suggestion? Thanks in advance.

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  • Why does this Haskell code produce the "infinite type" error?

    - by Charlie Flowers
    I am new to Haskell and facing a "cannot construct infinite type" error that I cannot make sense of. In fact, beyond that, I have not been able to find a good explanation of what this error even means, so if you could go beyond my basic question and explain the "infinite type" error, I'd really appreciate it. Here's the code: intersperse :: a -> [[a]] -> [a] -- intersperse '*' ["foo","bar","baz","quux"] -- should produce the following: -- "foo*bar*baz*quux" -- intersperse -99 [ [1,2,3],[4,5,6],[7,8,9]] -- should produce the following: -- [1,2,3,-99,4,5,6,-99,7,8,9] intersperse _ [] = [] intersperse _ [x] = x intersperse s (x:y:xs) = x:s:y:intersperse s xs And here's the error trying to load it into the interpreter: Prelude :load ./chapter.3.ending.real.world.haskell.exercises.hs [1 of 1] Compiling Main ( chapter.3.ending.real.world.haskell.exercises.hs, interpreted ) chapter.3.ending.real.world.haskell.exercises.hs:147:0: Occurs check: cannot construct the infinite type: a = [a] When generalising the type(s) for `intersperse' Failed, modules loaded: none. Thanks. EDIT: Thanks to the responses, I have corrected the code and I also have a general guideline for dealing with the "infinite type" error in Haskell: Corrected code intersperse _ [] = [] intersperse _ [x] = x intersperse s (x:xs) = x ++ s:intersperse s xs What the problem was: My type signature states that the second parameter to intersperse is a list of lists. Therefore, when I pattern matched against "s (x:y:xs)", x and y became lists. And yet I was treating x and y as elements, not lists. Guideline for dealing with the "infinite type" error: Most of the time, when you get this error, you have forgotten the types of the various variables you're dealing with, and you have attempted to use a variable as if it were some other type than what it is. Look carefully at what type everything is versus how you're using it, and this will usually uncover the problem.

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  • Configuring Novel iPrint client on ubuntu 13.10

    - by Mahdi Sadeghi
    Recently I have struggled a lot to make Novel iPrint client to work on my laptop. I need it to use Follow Me printers in our university(you can take your print form any printer). Using this tutorial from Novel, I tried to convert the rpm package and install it on Ubuntu 13.04 & 13.10. The post install script from installing generated deb package had a typo which I saw in post install messages and I fixed that. Now I have the client running. To see the client UI I installed cinnamon desktop(because unity does not have system tray and old solutions did'nt work to whitelist Novel clinet). I have iPrint plugin installed on firefox as well(I copied the shared object files to plugin directories). I try installing printers from provided ipp URL(which lists available printers on the server) with no success. After clicking the printer name I see this: I have various errors: Formerly firefox used to asked my network username/password for installing SSL printer but now it returns this: iPrint Printer - The printer is currently not available. However I can install non-SSL version but the printer location is either empty or points to: file:///dev/null even if I change it to the exact address which I see on working machines still it prints nothing. I have tried the novel command line tool, iprntcmd to print. It is being installed at: /opt/novell/iprint/bin/ msadeghi@werkstatt:/opt/novell/iprint/bin$ ./iprntcmd --addprinter ipp://iprint.rz.hs-offenburg.de/ipp/Follow-me\ -\ IPP iprntcmd v05.04.00 Adding printer ipp://iprint.rz.hs-offenburg.de/ipp/Follow-me - IPP. Added printer ipp://iprint.rz.hs-offenburg.de/ipp/Follow-me - IPP successfully. It adds the printer with empty location and again no print. What I found interesting is the log file at ~/.iprint/errors.txt with strange errors which I hope somebody here can understand. When I try to install the SSL printer I receive these logs(note that HP is my local printer and has nothing to do with iprint): Thu Oct 31 11:02:03 2013 Trace Info: iprint.c, line 6690 Group Info: IPRINT-lib Error Code: 4096 (0x1000) User ID: 1000 Error Msg: iPrint Lib - Bad URI type supplied (not IPP:, HTTP:, or HTTPS:). Debug Msg: IPRINTInterpretURI for file:///dev/null - Unknown Port Type - file Thu Oct 31 11:02:03 2013 Trace Info: iprint.c, line 6800 Group Info: IPRINT-lib Error Code: 4096 (0x1000) User ID: 1000 Error Msg: iPrint Lib - Bad URI type supplied (not IPP:, HTTP:, or HTTPS:). Debug Msg: IPRINTInterpretURI for hp:/usb/HP_LaserJet_1018?serial=KP103A1 - No Port type specified Thu Oct 31 11:02:05 2013 Trace Info: iprint.c, line 6690 Group Info: IPRINT-lib Error Code: 4096 (0x1000) User ID: 1000 Error Msg: iPrint Lib - Bad URI type supplied (not IPP:, HTTP:, or HTTPS:). Debug Msg: IPRINTInterpretURI for file:///dev/null - Unknown Port Type - file Thu Oct 31 11:02:05 2013 Trace Info: iprint.c, line 6800 Group Info: IPRINT-lib Error Code: 4096 (0x1000) User ID: 1000 Error Msg: iPrint Lib - Bad URI type supplied (not IPP:, HTTP:, or HTTPS:). Debug Msg: IPRINTInterpretURI for hp:/usb/HP_LaserJet_1018?serial=KP103A1 - No Port type specified Thu Oct 31 11:02:06 2013 Trace Info: mydoreq.c, line 676 Group Info: CLIB Error Code: 0 (0x0) User ID: 1000 Error Msg: Success Debug Msg: MyCupsDoFileRequest - httpReconnect failed (0) Thu Oct 31 11:02:06 2013 Trace Info: mydoreq.c, line 1293 Group Info: CUPS-IPP Error Code: 1282 (0x502) User ID: 1000 Error Msg: iPrint Printer - The printer is currently not available. Debug Msg: MyCupsDoFileRequest - IPP SERVICE UNAVAILABLE Thu Oct 31 11:02:06 2013 Trace Info: iprint.c, line 6690 Group Info: IPRINT-lib Error Code: 4096 (0x1000) User ID: 1000 Error Msg: iPrint Lib - Bad URI type supplied (not IPP:, HTTP:, or HTTPS:). Debug Msg: IPRINTInterpretURI for file:///dev/null - Unknown Port Type - file Thu Oct 31 11:02:06 2013 Trace Info: iprint.c, line 6800 Group Info: IPRINT-lib Error Code: 4096 (0x1000) User ID: 1000 Error Msg: iPrint Lib - Bad URI type supplied (not IPP:, HTTP:, or HTTPS:). Debug Msg: IPRINTInterpretURI for hp:/usb/HP_LaserJet_1018?serial=KP103A1 - No Port type specified Thu Oct 31 11:02:08 2013 Trace Info: iprint.c, line 6690 Group Info: IPRINT-lib Error Code: 4096 (0x1000) User ID: 1000 Error Msg: iPrint Lib - Bad URI type supplied (not IPP:, HTTP:, or HTTPS:). Debug Msg: IPRINTInterpretURI for file:///dev/null - Unknown Port Type - file Thu Oct 31 11:02:08 2013 Trace Info: iprint.c, line 6800 Group Info: IPRINT-lib Error Code: 4096 (0x1000) User ID: 1000 Error Msg: iPrint Lib - Bad URI type supplied (not IPP:, HTTP:, or HTTPS:). Debug Msg: IPRINTInterpretURI for hp:/usb/HP_LaserJet_1018?serial=KP103A1 - No Port type specified I should say that my friend can print using the same instructions on CrunchBang easily and another guy on 12.04 LTS but with more struggling. It worked for me on linux mint maya with my old laptop as well. Is there anybody out there who can help me to solve these problems? I am really disappointed with Novell and our university support. PS. I had the same problemwith 13.04. No matter if I am within the network or I connect with VPN, I have the same issues.

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  • Code folding for LaTeX in Emacs

    - by ShreevatsaR
    Is there an Emacs minor-mode (or piece of elisp code) that lets you selectively hide/show environments while in LaTeX mode? For instance, I would like to move to the beginning of a long \begin{figure} block, hit a keystroke, and have the contents of that figure environment hidden from view. Similarly with \begin{proof} and so on, and ideally even with \subsections. Is this possible? I just tried hs-minor-mode, allout-mode, and outline-minor-mode, but most of them don't recognize LaTeX's environments, e.g. hs-minor-mode fails with "scan error: unbalanced parentheses". I would prefer not to have to enter explicit folding marks like {{{ as in folding-mode. [Ideally it would be great if the folding were persistent, but I see that that question doesn't have an accepted answer yet.]

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  • CPP extension and multiline literals in Haskell

    - by jetxee
    Is it possible to use CPP extension on Haskell code which contains multiline string literals? Are there other conditional compilation techniques for Haskell? For example, let's take this code: -- If the next line is uncommented, the program does not compile. -- {-# LANGUAGE CPP #-} msg = "Hello\ \ Wor\ \ld!" main = putStrLn msg If I uncomment {-# LANGUAGE CPP #-}, then GHC refutes this code with a lexical error: [1 of 1] Compiling Main ( cpp-multiline.hs, cpp-multiline.o ) cpp-multiline.hs:4:17: lexical error in string/character literal at character 'o' Using GHC 6.12.1, cpphs is available. I confirm that using cpphs.compat wrapper and -pgmP cpphs.compat option helps, but I'd like to have a solution which does not depend on custom shell scripts. -pgmP cpphs does not work. P.S. I need to use different code for GHC < 6.12 and GHC = 6.12, is it possible without preprocessor?

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  • How to stop GHC from generating intermediate files?

    - by unknown
    When compiling a haskell source file via ghc --make foo.hs GHC always leaves behind a variety of intermediate files other than foo.exe. These are foo.hi and foo.o. I often end up having to delete the .hi and .o files to avoid cluttering up the folders. Is there a command line option for GHC not to leave behind its intermediate files? (When asked on #haskell, the best answer I got was ghc --make foo.hs && rm foo.hi foo.o.

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  • Reading status from Zebra Printer

    - by pmoreira
    Hi, I'm working on a project where we need to use a Zebra Printer for barcode labels. We're using C#, and we're doing OK on the printing side of things, sending raw ZPL strings to the printer (using winspool.drv). However, we also need to read from the printer, and no luck there. We need to get the status from the printer, which is the output to the ZPL command "~HS", so we can tell how many labels are in memory waiting to be printed. The EnumJobs() from winspool.drv only has jobs on the windows spool, and once they're sent to the printer, they're gone from that list. But that doesn't mean the label has been printed, since the printer has a peel sensor and only prints one label at a time, and we're obviously interested in sending batches of labels to the printer. I've tried something like (using the winspool.drv calls): OpenPrinter(szPrinterName, out hPrinter, IntPtr.Zero); WritePrinter(hPrinter, pBytes, dwCount, out dwWritten); // send the string "~HS" ReadPrinter(hPrinter, data, buff, out pcRead); But I get nothing on the ReadPrinter call. I don't even know if this is the right way of going at it. Anyone out there tackled this before? Thanks.

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  • Info on type family instances

    - by yairchu
    Intro: While checking out snoyman's "persistent" library I found myself wanting ghci's (or another tool) assistance in figuring out stuff. ghci's :info doesn't seem to work as nicely with type-families and data-families as it does with "plain" types: > :info Maybe data Maybe a = Nothing | Just a -- Defined in Data.Maybe ... > :info Persist.Key Potato -- "Key Potato" defined in example below data family Persist.Key val -- Defined in Database.Persist ... (no info on the structure/identity of the actual instance) One can always look for the instance in the source code, but sometimes it could be hard to find it and it may be hidden in template-haskell generated code etc. Code example: {-# LANGUAGE FlexibleInstances, GeneralizedNewtypeDeriving, MultiParamTypeClasses, TypeFamilies, QuasiQuotes #-} import qualified Database.Persist as Persist import Database.Persist.Sqlite as PSqlite PSqlite.persistSqlite [$persist| Potato name String isTasty Bool luckyNumber Int UniqueId name |] What's going on in the code example above is that Template-Haskell is generating code for us here. All the extensions above except for QuasiQuotes are required because the generated code uses them. I found out what Persist.Key Potato is by doing: -- test.hs: test = PSqlite.persistSqlite [$persist| ... -- ghci: > :l test.hs > import Language.Haskell.TH > import Data.List > runQ test >>= putStrLn . unlines . filter (isInfixOf "Key Potato") . lines . pprint where newtype Database.Persist.Key Potato = PotatoId Int64 type PotatoId = Database.Persist.Key Potato Question: Is there an easier way to get information on instances of type families and data families, using ghci or any other tool?

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  • "Ambigous type variable" error when defining custom "read" function

    - by Tener
    While trying to compile the following code, which is enhanced version of read build on readMay from Safe package. readI :: (Typeable a, Read a) => String -> a readI str = case readMay str of Just x -> x Nothing -> error ("Prelude.read failed, expected type: " ++ (show (typeOf > (undefined :: a))) ++ "String was: " ++ str) I get an error from GHC: WavefrontSimple.hs:54:81: Ambiguous type variable `a' in the constraint: `Typeable a' arising from a use of `typeOf' at src/WavefrontSimple.hs:54:81-103 Probable fix: add a type signature that fixes these type variable(s)` I don't understand why. What should be fixed to get what I meant? EDIT: Ok, so the solution to use ScopedTypeVariables and forall a in type signature works. But why the following produces very similar error to the one above? The compiler should infer the right type since there is asTypeOf :: a -> a -> a used. readI :: (Typeable a, Read a) => String -> a readI str = let xx = undefined in case readMay str of Just x -> x `asTypeOf` xx Nothing -> error ("Prelude.read failed, expected type: " ++ (show (typeOf xx)) ++ "String was: " ++ str)

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