[Haskell-cafe] IterIO: How to write use my inumReverse

Hi Haskell Cafe, I've defined the following reverse echo server that echos text back in reverse: module Programs.TcpEchoIterServer where import Control.Concurrent import Control.Exception import Control.Monad import Control.Monad.Trans import Data.IterIO import Data.IterIO.Inum import Network im

Re: [Haskell-cafe] Confused about my IterIO code

eof <- atEOFI unless eof $ do line <- lineI ifeed (L.concat [L.reverse line, C.pack "\n"]) loop Cheers, -John On 1 July 2011 01:20, wrote: > At Thu, 30 Jun 2011 23:53:02 +1000, > John Ky wrote: > > > > But all I've done is: &g

[Haskell-cafe] Confused about my IterIO code

Hi Hakell Cafe, I'm struggling to understand my unambitious IterIO code that somehow manages to work. Basically I run an echo server that is supposed to read from a socket line by line and write back to the socket with all the characters in the line reversed: import Control.Exception import Cont

[Haskell-cafe] How to flush with IterIO in echo server

Hi Haskell Cafe, I've written an echo server using just sockets: import Control.Concurrent import Control.Exception import Control.Monad import Network import Offsync.Data import System.IO import System.IO.Error (isEOFError) main = withSocketsDo $ do sListen <- listenOn (PortNumber 8000) put

Re: [Haskell-cafe] IterIO type restricted functions

Hi David, Good point. Not too fussed, though now that I think about it, I would have preferred it if enumFile' was defined in the tutorial rather than in the module. Cheers, -John On 29 June 2011 13:53, wrote: > At Wed, 29 Jun 2011 10:11:26 +1000, > John Ky wrote: > > &

[Haskell-cafe] IterIO type restricted functions

Hi all, >From the IterIO tutorial: enumFile' is like enumFile above, but type restricted to data in the lazy ByteString format, which is more efficient than plain Strings. (enumFile supports multiple types, but in this example there is not enough information for Haskell to choose one of them, so

Re: [Haskell-cafe] Cleaner way to write code and handle errors?

(\e -> if isEOFError e > then print e > else ioError e) >(putStrLn >=> const processLine) > > > On 28 June 2011 12:58, John Ky wrote: > > Hi Eric, Ivan, > > On 28 June 2011 18:32, Erik de Castro Lopo wrote: > >> &g

Re: [Haskell-cafe] Cleaner way to write code and handle errors?

Hi Eric, Ivan, On 28 June 2011 18:32, Erik de Castro Lopo wrote: > The hlint program would have flagged both of those and possibly > others. See: > Cool! It didn't flag either for me, but it recommended replacing ++ (show port)with ++ show port, if then else with unless, putStrLn (show x) with

[Haskell-cafe] Cleaner way to write code and handle errors?

Hi all, I'm practising my Haskell by writing a simple TCP echo server and finding that getting my program control to be succinct is rather tricky. In particular, I have return () everywhere, my error handling is verbose and I'm not entirely sure my recursion is the cleanest way syntactically to g

Re: [Haskell-cafe] Getting library documentation for installed packages on Windows

n `ghci`, then > >:m System.Directory >getAppUserDataDirectory "cabal" > > That'll show you the directory where your cabal config is. > > On Jun 21, 2011, at 9:03 PM, John Ky wrote: > > > Hi Svein, > > > > Where can I find this file

Re: [Haskell-cafe] Getting library documentation for installed packages on Windows

ns > should be fairly obvious in there. > On Jun 22, 2011 12:52 AM, "John Ky" wrote: > > Hi all, > > > > Lately I've been finding the Network module missing from the docs I > download > > from the GHC website, which brings me to the question: > >

[Haskell-cafe] Getting library documentation for installed packages on Windows

Hi all, Lately I've been finding the Network module missing from the docs I download from the GHC website, which brings me to the question: Is there any way I could generate libraries for this, the core libraries and all installed cabal packages into one reference so I can work offline? Cheers,

Re: [Haskell-cafe] What's the advantage of writing Haskell this way?

Thanks Malcom. I suspected that much, so I added it: data Stream m a = Chunks (m a) | EOF deriving (Show, Eq) instance (Monad m, MonadPlus m, Monoid (m a)) => Monoid (Stream m a) where mempty = Chunks mempty mappend (Chunks xs) (Chunks ys) = Chunks (xs `mappend` ys) mappend _ _ = EOF instance (

Re: [Haskell-cafe] What's the advantage of writing Haskell this way?

ap f xs) Failed, modules loaded: none. Cheers, -John On 31 May 2011 00:38, Brandon Moore wrote: > >From: John Ky > >Sent: Monday, May 30, 2011 8:01 AM > > > >Hi all, > > > >I'm trying to learn about enumerators by reading this paper and came > across

[Haskell-cafe] What's the advantage of writing Haskell this way?

Hi all, I'm trying to learn about enumerators by reading this paperand came across some code on page 2 that I found hard to digest, but I think I finally got it: import Data.Monoid data Stream a = Chunks [a] | EOF deriving (Show, Eq) in

Re: [Haskell-cafe] Circular pure data structures?

wrote: > Sufficient, but not good. > > Try zippers instead. > > > On 15 Jul 2009, at 08:29, John Ky wrote: > > Hello, >> >> Actually, I wanted to be able to create a tree structure when I can >> navigate both leaf-ward and root-ward. I didn't

Re: [Haskell-cafe] Circular pure data structures?

Hello, Actually, I wanted to be able to create a tree structure when I can navigate both leaf-ward and root-ward. I didn't actually care for equality. I think the tying the knot technique as mentioned by others is sufficient for this purpose. Cheers, -John On Wed, Jul 15, 2009 at 8:55 AM, Joh

[Haskell-cafe] Circular pure data structures?

Hello, Is it possible to create a circular pure data structure in Haskell? For example: a :: Data let b = getNext a let c = getNext b c == a -- Gives True Thanks, -John ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/m

Re: [Haskell-cafe] Where can I get GHC for Solaris?

program built for sparc-sun-solaris2.9 j...@sun05:~ $ uname -a SunOS sun05 5.9 Generic_118558-30 sun4u sparc SUNW,Sun-Fire-280R Thanks, -John On Wed, Jul 8, 2009 at 4:48 PM, Aycan iRiCAN wrote: > Çar, 2009-07-08 tarihinde 09:55 +1000 saatinde, John Ky yazdı: > > Hi, > > > >

[Haskell-cafe] Where can I get GHC for Solaris?

Hi, Anyone know where I can get the GHC compiler and libraries for Solaris?: SunOS sun05 5.9 Generic_118558-30 sun4u sparc SUNW,Sun-Fire-280R I tried to compile GHC myself and got the following error: $ ./configure --enable-hc-boot checking build system type... sparc-sun-solaris2.9 checking hos

Re: [Haskell-cafe] How to pretty print code efficiently

Hi all, Thanks everyone for the help. The HughesPJ module works well for me. Cheers, -John On Mon, Jul 6, 2009 at 3:49 AM, Chris Eidhof wrote: > On 4 jul 2009, at 05:13, Alexander Dunlap wrote: > > On Fri, Jul 3, 2009 at 6:45 PM, John Ky wrote: >> >>> Hi, >

[Haskell-cafe] How to pretty print code efficiently

Hi, Currently I'm pretty printing code by building arrays of strings and calling indent. For example: instance JavaPrintableNamed AST.EnumeratedType where javaLinesNamed parentName (AST.EnumeratedType memberDefinitions) = [ "public enum " ++ asJavaId(parentName) , "{" ] ++ m

Re: [Haskell-cafe] Why are these record accesses ambiguous

On Sat, Jun 6, 2009 at 6:41 PM, Luke Palmer wrote: > On Sat, Jun 6, 2009 at 1:48 AM, John Ky wrote: > >> Hi Haskell Cafe, >> >> In the following code, I get an error saying Ambiguous occurrence `x'. >> Why can't Haskell work out which x to call ba

[Haskell-cafe] Why are these record accesses ambiguous

Hi Haskell Cafe, In the following code, I get an error saying Ambiguous occurrence `x'. Why can't Haskell work out which x to call based on the type of getA? Thanks -John #!/usr/bin/env runhaskell > {-# LANGUAGE DisambiguateRecordFields #-} > import A > import B > > main = do >let xx = ge

[Haskell-cafe] Conversion from string to array

Hi Haskell Cafe, I'm trying to send stuff over UDP. To do that, I've written a test program that sends strings across. That was fine, but I wanted to send binary data too. So I tried that only to find I am having difficulty putting together some binary data. For examples take the fromHex funct

Re: [Haskell-cafe] Record initialise question (RESOLVED)

On Fri, Jun 5, 2009 at 8:05 PM, Martijn van Steenbergen < mart...@van.steenbergen.nl> wrote: > Hi John, > > John Ky wrote: > >> > full = do >> > let myOrder = init -- [1] >> > { item = Just ini

[Haskell-cafe] Record initialise question

Hi all, I have some sample code: > full = do > let myOrder = initOrder > { item = Just initItem > { itemId = "Something" > } > , operation = Just Buy > } > putStrLn $ show myOrder > return () This is just a test

Re: [Haskell-cafe] Type families not as useful over functions

Hi Johnaton, Ah yes. That makes sense. Is there a way to define type r to be all types except functions? -John On Fri, Feb 13, 2009 at 10:44 AM, Jonathan Cast wrote: > On Fri, 2009-02-13 at 10:34 +1100, John Ky wrote: > > Hi Haskell Cafe, > > > > I tried using type fa

Re: [Haskell-cafe] Type families not as useful over functions

instead of "broadcast fs a b" use > > fs |$| a |$| b > > ? > > > On 13 Feb 2009, at 02:34, John Ky wrote: > > Hi Haskell Cafe, >> >> I tried using type families over functions, but when I try it complains >> that the two lines marked conflict w

[Haskell-cafe] Type families not as useful over functions

Hi Haskell Cafe, I tried using type families over functions, but when I try it complains that the two lines marked conflict with each other. class Broadcast a where type Return a broadcast :: a -> Return a instance Broadcast [a -> r] where type Return [a -> r] = a -> [r] -- Conflict!

[Haskell-cafe] Writing a generic event handler

Hi Haskell Cafe, I'm interested in writing some events and event handlers in Haskell. I already have a Loop data structure, and I intend to use it for this purpose: -- Create event tEvent <- newLoop (return ()) -- Register event handlers tHandler1 <- newLoop (putStrLn "Handler1") tHandler2 <- n

Re: [Haskell-cafe] Why does sleep not work?

es sleep. Thanks, -John On Tue, Feb 10, 2009 at 8:59 AM, Peter Verswyvelen wrote: > Hi John, > Which sleep are you using? From which module? Can you show the full source > with import statements? > > Cheers, > Peter > > 2009/2/9 John Ky > >> Hi Haskell Caf

[Haskell-cafe] Why does sleep not work?

Hi Haskell Cafe, I wrote very short program to sleep for 5 seconds compiled with the -threaded option in ghc on the Mac OS X 1.5. I am finding that using the sleep function doesn't sleep at all, whereas using threadDelay does: main = do putStrLn "Waiting for 5 seconds." threadDelay 5

Re: [Haskell-cafe] Type families are awesome

Thanks Luke, Works great. On Wed, Jan 21, 2009 at 7:35 PM, Luke Palmer wrote: > 2009/1/21 John Ky >> >> *Main> let x = lookup >> *Main> let y = Fx.Data.Map.lookup >> >> :1:8: >> Ambiguous type variable `ma' in the constraint: >>

[Haskell-cafe] Type families are awesome

Hi Haskell Cafe, I'm finding that I really like type families. For instance, the GHC.List.lookup and Data.Map.lookup functions annoy me because their names clash, yet their type are so similar. With type families, I could define a more generic lookup function like this: import Data.Map as MAP i

Re: [Haskell-cafe] Different return type?

Hi Daniel, When would I use either? What are the trade-offs? Thanks -John On Mon, Jan 19, 2009 at 1:13 PM, Daniel Fischer wrote: > Am Montag, 19. Januar 2009 02:44 schrieb John Ky: > > Hi, > > > > Possibly a silly question but is it possible to have a function that

[Haskell-cafe] Different return type?

Hi, Possibly a silly question but is it possible to have a function that has a different return type based on it's first argument? For instance data Person = Person { name :: String, ... } data Business = Business { business_number :: Int, ...} key person = name person key business = business_n

[Haskell-cafe] Debugging STM

Hi, Does anyone have any advice on how to inspect complex TVar data structures that may include cycles? They're opaque as far as Show goes. And sometimes I'd like a more comprehensive view of my data structures at the ghci prompt rather than the dribs and drabs I get by typing "x <- atomically $

Re: [Haskell-cafe] Re: Tying a simple circularly STM linked list

Thanks Chris, The undefined works for me. -John On Wed, Jan 7, 2009 at 11:11 AM, ChrisK wrote: > You can use "undefined" or "error ..." : > > {-# LANGUAGE RecursiveDo #-} >> import Control.Concurrent.STM >> import Control.Monad.Fix >> >> -- Transactional loop. A loop is a circular link list.

[Haskell-cafe] Tying a simple circularly STM linked list

Hi, I've written a circularly linked list, but there is some code in it I feel is redundant, but don't know how to get rid of: -- Transactional loop. A loop is a circular link list. data Loop a = ItemLink { item :: a , prev :: TVar (Loop a) , next :: TVar (Loop a) }

[Haskell-cafe] Transactional container for storing anonymous deletable objects

Hi, I need a container data structure for storing anonymous objects - most likely things that have not value such as STM (), but probably other things as well. This will allow me to later on, iterate over the container and process those objects. Additionally I have the requirement that I need to

[Haskell-cafe] Data.Map add only if not exist and return true if added

Hi, I'm looking for a function for Data.Map that will insert a new key and value into the map if the key doesn't already exist in the map. When the key already exists, I don't want the value updated in the map. Additionally, I want to know whether the key/value was inserted or not so that I can

[Haskell-cafe] Overlapping instances

Hi, I've got the following code which tries to implement a TShow class, which is equivalent to Show, except it is supposed to work on TVar types as well. import GHC.Conc createEngine :: String -> Int -> Int -> IO Engine createEngine name major minor = do tUsers <- newTVarIO [] return $ Eng

[Haskell-cafe] Deriving something else?

Hi, I've defined a class and some instances, which I'm hoping would help me "show" values of types that may include transactional elements. class TShow a where tshow :: a -> IO String instance Show (TVar a) where show = "%" instance (Show a) => TShow a where tshow a = return $ show a

Re: [Haskell-cafe] Is unsafePerformIO safe here?

Inline. On Mon, Dec 8, 2008 at 1:28 PM, Luke Palmer <[EMAIL PROTECTED]> wrote: > 2008/12/7 John Ky <[EMAIL PROTECTED]> > >> Does that mean there is no place to store state while running the >> interpreter and that I have to put the state elsewhere such as a file?

Re: [Haskell-cafe] Is unsafePerformIO safe here?

2008 at 11:51 AM, Thomas Davie <[EMAIL PROTECTED]> wrote: > > On 8 Dec 2008, at 01:28, John Ky wrote: > > Hi, >> >> Is the following safe? >> >> moo :: TVar Int >> moo = unsafePerformIO $ newTVarIO 1 >> >> I'm interested in wr

Re: [Haskell-cafe] Reading showables

x -> show (read x)) "123" *** Exception: Prelude.read: no parse -John On Mon, Dec 8, 2008 at 12:08 PM, Jonathan Cast <[EMAIL PROTECTED]>wrote: > On Mon, 2008-12-08 at 11:16 +1100, John Ky wrote: > > Hi Thomas, > > > > So "show . read" and "\x -&g

[Haskell-cafe] Is unsafePerformIO safe here?

Hi, Is the following safe? moo :: TVar Int moo = unsafePerformIO $ newTVarIO 1 I'm interested in writing a stateful application, and I wanted to start with writing some IO functions that did stuff on some state and then test them over long periods of time in GHCi. I was worried I might be depen

Re: [Haskell-cafe] Reading showables

t; Often there is a show instance with no read or vice versa, and > sometimes even when there is both read and show they are not inverses. > > Thomas. > > main = show . read > > > > Am 7. Dezember 2008 14:11 schrieb John Ky <[EMAIL PROTECTED]>: > > Hi, > > >

[Haskell-cafe] Reading showables

Hi, Is there a way to read Showables? main = do putStrLn $ show $ read Thanks -John ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] What is this function? (RESOLVED)

lah -} I was basically after exhaustively generating lots ASTs given a template AST with lots of leaf values changed. Thanks, -John On Thu, Oct 16, 2008 at 8:39 PM, Luke Palmer <[EMAIL PROTECTED]> wrote: > 2008/10/16 John Ky <[EMAIL PROTECTED]>: > > Hi, > > >

[Haskell-cafe] What is this function?

Hi, I've written this function here: scramble [] = [] scramble [x] = [[z] | z <- scramble x] scramble (x:xs) = [(y:z)|y <- scramble x, z <- scramble xs] and (I think) it roughly does what I want it to: *Main> scramble ([]::[Int]) [] *Main> scramble ([1]::[Int]) [[1],[

[Haskell-cafe] How to do a special kind of comment with the TokenParser

Hi, TokenParser supports two kinds of comments, the multi-line comments (ie. {- -}) and the single line comments (ie. -- \n). The language I am trying to parse, however, has comments which are neither. The -- acts like a single line comment which extends to the end of the line usually, but can al

Re: [Haskell-cafe] GHC throws IOError on Win32 when there is no console

Hi Paul, Can I have your code that doesn't work? I want to fiddle with it a bit. Thanks -John On 2/12/07, Paul Moore <[EMAIL PROTECTED]> wrote: On 09/02/07, Paul Moore <[EMAIL PROTECTED]> wrote: > It probably wouldn't be hard to write a reasonably general wrapper for > this, but it's a bit

Re: [Haskell-cafe] GHC throws IOError on Win32 when there is no console

Hi Duncan, Thanks for your comments. In the context of a haskell process running as a Windows service, a message box is useless, because Haskell services do not have a GUI and cannot interact with the desktop. -John ___ Haskell-Cafe mailing list Haske

[Haskell-cafe] Re: GHC throws IOError on Win32 when there is no console

Sorry, I should clarify. I am writing about applications compiled with GHC. -John On 2/10/07, John Ky <[EMAIL PROTECTED]> wrote: Hi, I noticed on Windows that when I use IO functions that write to stdout when the process is lacking a console, those functions throw an IOError. I'

[Haskell-cafe] GHC throws IOError on Win32 when there is no console

Hi, I noticed on Windows that when I use IO functions that write to stdout when the process is lacking a console, those functions throw an IOError. I'm not sure if this also occurs for stderr because I haven't tried it. Some classes of processes are created without a console because they never

Re: [Haskell-cafe] A function callable from C

Stefan O'Rear <[EMAIL PROTECTED]> wrote: On Tue, Feb 06, 2007 at 12:40:38PM +1100, John Ky wrote: > Hi Stefan, > > In that case, how do I marshall [String] to Ptr (Ptr CChar)? look at Foreign.C.String and Foreign.Ptr service-002.rename_as_zip Description: Binary data _

Re: [Haskell-cafe] A function callable from C

Hi Stefan, In that case, how do I marshall [String] to Ptr (Ptr CChar)? Thanks -John On 2/6/07, Stefan O'Rear <[EMAIL PROTECTED]> wrote: You have to use a type that C's tiny brain understains. IANAWP but I'm guessing you want: type ServiceMainClosure = DWORD -> Ptr (Ptr CChar) -> IO () for

[Haskell-cafe] A function callable from C

Hi, The following code works: type ServiceMainClosure = DWORD -> IO () foreign import ccall "wrapper" mkServiceMainClosure :: ServiceMainClosure -> IO (FunPtr ServiceMainClosure) But the following doesn't: type ServiceMainClosure = DWORD -> [String] -> IO () foreign import ccall "wrappe

[Haskell-cafe] Re: Win32 help please

Hi, I tried as suggested: hsc2hs mywin32.hsc ghc -c -O -fffi mywin32.hs which allows me to use ghci. And if I add a main function, I can also do this: hsc2hs mywin32.hsc ghc -fffi mywin32.hs -package Win32 Thanks everyone for the help. -John _

[Haskell-cafe] Win32 help please

Hi, I'm interested in writing accessing some Win32 functions not available from GHC. I wrote this short little file and tried to compile: mywin32.hsc module MyWin32 where #include Then tried to compile it like this: # hsc2hs mywin32.hsc # ghc -fffi mywin32.hs C:/system/ghc/ghc-6.6/libHSrt

[Haskell-cafe] Boost equivalent

Hi, Does the Haskell community have an equivalent to C++ community's Boost project with the aim of writing libraries for the eventual inclusion into Haskell? Thanks -John ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/ma

Re: [Haskell-cafe] Re: Paths to tree

Hi apfelmus, Your code is fine, I like it. A minor hint is that mergeForest is a fold: mergeForest = foldr merge [] Also, we have prettyPrint = putStr . unlines . prettyPrint' $ forest Nice help on the simple things. I can't know, but it doesn't seem unreasonable that you intend to use

Re: [Haskell-cafe] Paths to tree

both of which to me is considerably harder. Thanks for the tip. -John On 1/29/07, Tomasz Zielonka <[EMAIL PROTECTED]> wrote: On Mon, Jan 29, 2007 at 10:10:47PM +1100, John Ky wrote: > I've written some code and was wondering if there was a better way to write > it in terms of re

[Haskell-cafe] Paths to tree

Hi, I've written some code and was wondering if there was a better way to write it in terms of readability, brevity and/or efficiency. The function concerned is pathsToForest which takes a list of paths (ie. [[String]]) and converts it into a tree structure where the individual nodes are the nam

Re: [Haskell-cafe] A function for Maybes (RESOLVED)

Thanks -John On 1/26/07, Brandon S. Allbery KF8NH <[EMAIL PROTECTED]> wrote: On Jan 25, 2007, at 9:15 , John Ky wrote: > Is there a built-in function that already does this? > > foo :: (a -> b) -> Maybe a -> Maybe b > foo f m > | isNothing m = Nothing >

[Haskell-cafe] A function for Maybes

Is there a built-in function that already does this? foo :: (a -> b) -> Maybe a -> Maybe b foo f m | isNothing m = Nothing | otherwise = Just (f (fromJust m)) *Main> foo (+2) (Just 3) Just 5 *Main> foo (+2) Nothing Nothing If so what is it? If not, what should I call it? Thanks -John _

Re: [Haskell-cafe] Trouble understanding records and existential types

Let me try this option and see how I go. Thanks -John On 1/25/07, Brandon S. Allbery KF8NH <[EMAIL PROTECTED]> wrote: > (b) I think you *can* do this with a class: > > class Node a where >name :: a -> String > > data Branch = Branch { brName :: String, ... } > data Leaf = Leaf { lName ::

Re: [Haskell-cafe] Trouble understanding records and existential types

On 1/25/07, Brandon S. Allbery KF8NH <[EMAIL PROTECTED]> wrote: I'm probably missing something, but: (a) Why not: data ANode = Branch { name :: String, description :: String, children :: [AnyNode] } | Leaf { name :: String, value :: String } -- this reuse is legal -- leaving Node a

[Haskell-cafe] Trouble understanding records and existential types

Hi, A while back I asked about OO programming in Haskell and discovered existential types. I understood that existential types allowed me to write heterogeneous lists which seemed sufficient at the time. Now trying to combine those ideas with records: data AnyNode = forall a. Node a => AnyNode

[Haskell-cafe] What does the withProcessHandle_ function do?

I want to learn how to use FFI with Win32, so I'm looking through the GHC source code. I encountered the function terminateProcess :: ProcessHandle -> IO () terminateProcess ph = do withProcessHandle_ ph $ \p_ -> case p_ of ClosedHandle _ -> return p_ OpenHandle h -> do throwErr

Re: [Haskell-cafe] CTRL+C in ghci.exey

2,283,284,285,286,287 ,288,289,290,291,292,293,294,295,296,297,298,299,300,301,302,303,304,305,306,307 ,308,309,3 Thanks -John On 1/12/07, Stefan O'Rear <[EMAIL PROTECTED]> wrote: On Fri, Jan 12, 2007 at 05:07:04PM +1100, John Ky wrote: > Hi, > > Is it possible to use CTRL+C or equivalent to interrupt a co

[Haskell-cafe] CTRL+C in ghci.exe

Hi, Is it possible to use CTRL+C or equivalent to interrupt a computation or I/O and return to the ghci prompt? Thanks -John ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] UDP client/server

Nevermind, I just got the client to work: echoClient :: IO () echoClient = withSocketsDo $ do sock <- socket AF_INET Datagram 0 n <- sendTo sock "hi" (SockAddrInet echoPort 0x0107f) return () Thanks everyone for your help. -John On 1/12/07, John Ky <[EMAIL PR

Re: [Haskell-cafe] UDP client/server

quot; putStrLn "[d]" return () I get: *Main> echoClient [a] [b] *** Exception: connect: failed (Cannot assign requested address (WSAEADDRNOTAVAI L)) Thanks -John On 1/12/07, Gregory Wright <[EMAIL PROTECTED]> wrote: Hi John, On Jan 11, 2007, at 10:35 AM, Gregor

[Haskell-cafe] UDP client/server

Hello, Does anyone know where I can find a simple UDP client/server written in Haskell? Something along the lines of an echo server would do. Thanks -John ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/

[Haskell-cafe] Re: Designing an object model in Haskell (RESOLVED)

Hi all, I'm now using existential types. I avoided learning about them because the name sounded so highly technical and obscure it did not occur to me they could be related to OO. Thanks, -John On 12/7/06, John Ky <[EMAIL PROTECTED]> wrote: Hi, I've got an object mod

[Haskell-cafe] Designing an object model in Haskell

Hi, I've got an object model that I have a difficult time conceptualising how it might look like in Haskell: class Element { } class Inline : Element { } class ParentInline : Inline { List children; } class Bold : ParentInline { } class Underline : ParentInline { } class Link : ParentInlin

[Haskell-cafe] Testing non-exported functions using ghci

Hello,I have modules that don't export some functions.  Is there a way I can access them from ghci without exporting them?Thanks-John ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] What is the best way to preserve the order of a list (RESOLVED)

Thanks Stefan,-JohnOn 11/1/06, Stefan Holdermans <[EMAIL PROTECTED]> wrote: John,> My question is, how do I preserve the ordering of entities in my> list and still be able to assign the proper order values to each> entity?  Is there an efficient way to do this?  How else might I > improve my orderB

[Haskell-cafe] What is the best way to preserve the order of a list

Hi,I have a list of entities.  Each entity has a priority field and an order field.  The priority field contain the input values to my algorithm, the order fields contain the output value of my algorithm.  My algorithm needs to assign 1 to the order field of the entity with the lowest priority valu

[Haskell-cafe] UTF and Parsec

Hi,I'm interested in using Parsec to parse utf-8 files and do some processing and output a utf-8 document.  Is there anything I should be aware of?  Does GHC handle all the utf-8 stuff automatically?  What does it mean when I find that parsec is picking up "" at the beginning of the file. Thanks

[Haskell-cafe] Re: Best way to write endsWith (RESOLVED)

something in Haskell can be so short.5. Operators really are awesome.-JohnOn 10/22/06, John Ky <[EMAIL PROTECTED]> wrote:Hello, I have this function here:> endsWith :: Eq a => [a] -> [a] -> Bool> endsWith suffix list>   | lengthDifference < 0 = False>   | otherwise

[Haskell-cafe] Best way to write endsWith

Hello,I have this function here:> endsWith :: Eq a => [a] -> [a] -> Bool> endsWith suffix list>   | lengthDifference < 0 = False>   | otherwise = (drop lengthDifference list) == suffix >   where lengthDifference = (length list) - (length suffix)Would this be the preferred function argument order? 

Re: [Haskell-cafe] Trying to write a TCP proxy

Hi all, Thanks for all your help. I finally realised that hGetLine strips out the "\n" newline character so when I forward the line to the server, I need to append it again. Here's my implementation. -John main = proxyServe proxyServe = withSocketsDo $ do socket <- listenOn $ PortNumber

Re: [Haskell-cafe] Re: Trying to write a TCP proxy

t; wrote: On Wed, 20 Sep 2006, John Ky wrote: > Actually, it blocks on: > > >putStrLn contents > > It even blocks if I replace it with: > > >print $ length contents > > Is there some kind of magic happening here? > No, but you're trying to do magic

Re: [Haskell-cafe] Trying to write a TCP proxy

Hi Bulat, Thanks. Yes it helps with an earlier implementation I wrote (below). But surely there must be a better way to write this. My code is way to verbose. -John --- doProxyServer handleToClient handleToServer = do eof <- hIsEOF handleToServer if not eof then do ready <- hR

[Haskell-cafe] Re: Trying to write a TCP proxy

Actually, it blocks on: putStrLn contents It even blocks if I replace it with: print $ length contents Is there some kind of magic happening here? -John On 9/20/06, John Ky <[EMAIL PROTECTED]> wrote: Hello, I'm trying to use haskell to put together a TCP proxy I can

[Haskell-cafe] Trying to write a TCP proxy

Hello, I'm trying to use haskell to put together a TCP proxy I can put between my browser and my webserver. This is as far as I got. The webserver isn't returning my request: listen = withSocketsDo $ do putStrLn "Listening..." socket <- listenOn $ PortNumber 8082 (handleToClient, hostNa