- Glasgow-haskell-users

RE: Problem with ghc on Windows ME
by Simon Marlow 29 Jan '04

29 Jan '04

> > The > implementation of > > rawSystem will attempt to compensate for the internal > translation that > > Windows does on the command-line; on Unix no translation is > necessary. > > So clients of rawSystem should be more portable, because > they don't have > > to know about quoting that happens under the hood. > > This is probably a silly naming question, but aren't the names of > 'System.system' and 'rawSystem' the wrong way round? On the face > of things, it would seem sensible for System.system to have the more > portable behaviour, and rawSystem to be dependent on local > conventions. > After all, System.system is defined in the official Libraries Report > making no mention of any portability problems, whereas the name 'raw' > suggests that no interpretation/quoting is going on, and hence it > may be highly dependent on the underlying system. Indeed. The existing behaviour for System.system is (I assume) derived from the POSIX sytem(), which also executes a command using the shell. The naming is sensible in one respect: system goes via the shell, whereas rawSystem bypasses the shell. Unfortunately we can't easily change System.system to be the raw version, because they have different types and to do so would break lots of code. System.Process will have a more reasonable interface, when I get around to finishing it. Cheers, Simon

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detecting memory size?
by Ketil Malde 29 Jan '04

29 Jan '04

Hi, Is it possible to detect memory (i.e. RAM, not virtual memory) size from inside a Haskell program (so that I can keep my program from growing too large with consequent thrashing)? And if so, to what degree of portability? -kzm -- If I haven't seen further, it is by standing in the footprints of giants

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Re: Network problem with ghc on WinXP
by robin abraham 29 Jan '04

29 Jan '04

Works like a charm now :) Thank you for the insight. Robin. >Hi there, > >looks like a network byte-order vs host byte-order gotcha. >Never use the PortNum constructor, but declare 'portnum' >to have type PortNumber and simply drop the use of PortNum >in your code alltogether. Alternatively, use intToPortNumber >to translate between Int and PortNumber. > >hth >--sigbjorn > >----- Original Message ----- >From: "robin abraham" <abraharo(a)cs.orst.edu> >To: <glasgow-haskell-users(a)haskell.org> >Sent: Wednesday, January 28, 2004 21:57 >Subject: Network problem with ghc on WinXP > > >> Hi, >> >> I have ghc-6.0.1 on WinXP and Solaris. I have a simple echo server >(server.hs >> given below) and client (client.hs given below) and I encounter the >following: >> 1) server.hs compiled and running on Solaris: >> a) client.hs (Solaris) can connect. >> b) client.hs (WinXP) cannot connect. >> c) telnet (WinXP) can connect. >> d) telnet (Solaris) can connect. >> e) Scan of port 3000 shows server is listening. >> >> 2) server.hs compiled and running on WinXP: >> a) client.hs (Solaris) cannot connect. >> b) client.hs (WinXP) can connect. >> c) telnet (WinXP) cannot connect. >> d) telnet (Solaris) cannot connect. >> e) Scan of ports does not show server. >> >> Basically, when the server is running on WinXP, only the Haskell program >> client.hs (also running on the same WinXP machine) can "converse" with it >> through the socket connection. To verify this, I wrote a client in C# - >from the >> WinXP machine, it can connect to server running on my Solaris machine but >not to >> server on the same WinXP machine. >> >> Why isn't the server program on WinXP not behaving itself? Any >help/guidance >> would be highly appreciated. >> >> Thank you. >> Robin. >> >> -- server.hs >> module Main where >> >> import SocketPrim >> import Concurrent >> import System (getArgs,exitFailure) >> import Exception(finally) >> import MVar >> import IO >> >> server_sock :: IO (Socket) >> server_sock = do >> s <- socket AF_INET Stream 6 >> setSocketOption s ReuseAddr 1 >> bindSocket s (SockAddrInet (PortNum portnum) iNADDR_ANY) >> listen s 2 >> return s >> >> echo_server :: Socket -> IO () >> echo_server s = do >> (s', clientAddr) <- accept s >> h <- socketToHandle s' ReadWriteMode >> proc <- read_data s' 0 >> putStrLn ("server processed "++(show proc)++" bytes") >> sClose s' >> where >> read_data sock totalbytes = do >> str <- recv sock 18 >> putStrLn ("Server recv: " ++ str) >> if ((length str) >= 18) >> then do >> putStrLn ("Server read: " ++ str) >> writ <- send sock str >> putStrLn ("Server wrote: " ++ str) >> read_data sock $! (totalbytes+(length $! str)) >> else do >> putStrLn ("server read: " ++ str) >> return totalbytes >> >> message = "Hello there sailor" >> portnum = 3000 >> >> main = withSocketsDo $ do { >> ~[n] <- getArgs; >> ssock <- server_sock; >> s <- myForkIO (echo_server ssock); >> join s; >> putStrLn "join s"; >> } >> >> myForkIO :: IO () -> IO (MVar ()) >> myForkIO io = do >> mvar <- newEmptyMVar >> forkIO (io `finally` putMVar mvar ()) >> return mvar >> >> join :: MVar () -> IO () >> join mvar = readMVar mvar >> >> -- end of server.hs >> >> -- *********************************************** >> >> -- client.hs >> >> module Main where >> >> import SocketPrim >> import Concurrent >> import System (getArgs,exitFailure) >> import Exception(finally) >> import MVar >> import IO >> >> local = "128.193.39.108" >> message = "Hello there sailor" >> portnum = 3000 >> >> client_sock = do >> s <- socket AF_INET Stream 6 >> ia <- inet_addr local >> connect s (SockAddrInet (PortNum portnum) ia) >> return s >> >> echo_client n = do >> s <- client_sock >> drop <- server_echo s n >> sClose s >> where >> server_echo sock n = if n > 0 >> then do >> send sock message >> putStrLn ("Client wrote: " ++ message) >> str <- recv sock 19 >> if (str /= message) >> then do >> putStrLn ("Client read error: " ++ str) >> exitFailure >> else do >> putStrLn ("Client read success") >> server_echo sock (n-1) >> else do >> putStrLn "Client read nil" >> return [] >> >> main = withSocketsDo $ do >> ~[n] <- getArgs >> c <- myForkIO (echo_client (read n::Int)) >> join c >> putStrLn "join c" >> >> myForkIO :: IO () -> IO (MVar ()) >> myForkIO io = do >> mvar <- newEmptyMVar >> forkIO (io `finally` putMVar mvar ()) >> return mvar >> >> join :: MVar () -> IO () >> join mvar = readMVar mvar >> >> -- end of client.hs >>

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Network problem with ghc on WinXP
by robin abraham 29 Jan '04

29 Jan '04

Hi, I have ghc-6.0.1 on WinXP and Solaris. I have a simple echo server (server.hs given below) and client (client.hs given below) and I encounter the following: 1) server.hs compiled and running on Solaris: a) client.hs (Solaris) can connect. b) client.hs (WinXP) cannot connect. c) telnet (WinXP) can connect. d) telnet (Solaris) can connect. e) Scan of port 3000 shows server is listening. 2) server.hs compiled and running on WinXP: a) client.hs (Solaris) cannot connect. b) client.hs (WinXP) can connect. c) telnet (WinXP) cannot connect. d) telnet (Solaris) cannot connect. e) Scan of ports does not show server. Basically, when the server is running on WinXP, only the Haskell program client.hs (also running on the same WinXP machine) can "converse" with it through the socket connection. To verify this, I wrote a client in C# - from the WinXP machine, it can connect to server running on my Solaris machine but not to server on the same WinXP machine. Why isn't the server program on WinXP not behaving itself? Any help/guidance would be highly appreciated. Thank you. Robin. -- server.hs module Main where import SocketPrim import Concurrent import System (getArgs,exitFailure) import Exception(finally) import MVar import IO server_sock :: IO (Socket) server_sock = do s <- socket AF_INET Stream 6 setSocketOption s ReuseAddr 1 bindSocket s (SockAddrInet (PortNum portnum) iNADDR_ANY) listen s 2 return s echo_server :: Socket -> IO () echo_server s = do (s', clientAddr) <- accept s h <- socketToHandle s' ReadWriteMode proc <- read_data s' 0 putStrLn ("server processed "++(show proc)++" bytes") sClose s' where read_data sock totalbytes = do str <- recv sock 18 putStrLn ("Server recv: " ++ str) if ((length str) >= 18) then do putStrLn ("Server read: " ++ str) writ <- send sock str putStrLn ("Server wrote: " ++ str) read_data sock $! (totalbytes+(length $! str)) else do putStrLn ("server read: " ++ str) return totalbytes message = "Hello there sailor" portnum = 3000 main = withSocketsDo $ do { ~[n] <- getArgs; ssock <- server_sock; s <- myForkIO (echo_server ssock); join s; putStrLn "join s"; } myForkIO :: IO () -> IO (MVar ()) myForkIO io = do mvar <- newEmptyMVar forkIO (io `finally` putMVar mvar ()) return mvar join :: MVar () -> IO () join mvar = readMVar mvar -- end of server.hs -- *********************************************** -- client.hs module Main where import SocketPrim import Concurrent import System (getArgs,exitFailure) import Exception(finally) import MVar import IO local = "128.193.39.108" message = "Hello there sailor" portnum = 3000 client_sock = do s <- socket AF_INET Stream 6 ia <- inet_addr local connect s (SockAddrInet (PortNum portnum) ia) return s echo_client n = do s <- client_sock drop <- server_echo s n sClose s where server_echo sock n = if n > 0 then do send sock message putStrLn ("Client wrote: " ++ message) str <- recv sock 19 if (str /= message) then do putStrLn ("Client read error: " ++ str) exitFailure else do putStrLn ("Client read success") server_echo sock (n-1) else do putStrLn "Client read nil" return [] main = withSocketsDo $ do ~[n] <- getArgs c <- myForkIO (echo_client (read n::Int)) join c putStrLn "join c" myForkIO :: IO () -> IO (MVar ()) myForkIO io = do mvar <- newEmptyMVar forkIO (io `finally` putMVar mvar ()) return mvar join :: MVar () -> IO () join mvar = readMVar mvar -- end of client.hs

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RE: Problem with ghc on Windows ME
by Simon Peyton-Jones 29 Jan '04

29 Jan '04

| For system, I do need doublequotes in arguments (e.g., when passing | complex option flags to the programs invoked, or when the arguments | contain strings). Can that really always be avoided for rawSystem? Perhaps the comment is misleading. You can indeed put quotes in arguments (they get escaped). It's backslash followed by quote that I don't know how to get into an argument Simon

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RE: Generics...(ish)
by MR K P SCHUPKE 28 Jan '04

28 Jan '04

I have read the "Scrap Your Boilerplate: A Practical Design Pattern for Generic Programming" and have worked out how to do it. This seems much better than using Template Haskell for this kind of problem. I used mkQ and extQ to convert from various types that are allowed in the record structure, to an algebraic enumeration type that codes the valid types. This allows using "everything (++)" to convert a record (tuple type) to a List of type-names in an enumeration. This is a very neet and compact way of doing it. This enables me to define a database table in haskell (where a record represents a table with columns of the given types), for example: data TestTable = TestTable { column1 :: ColumnType Int, column2 :: ColumnType Float, column3 :: ColumnType String } type ColumnType a = String -- use phantom types to statically type check sql... testTable :: TestTable testTable = TestTable { column1 = "id", column2 = "aFloatValue" column3 = "aString" } Using generics I can now generate a list: [("id",SqlInt),("aFloatValue",SqlFloat),("aString",SqlString)] which can be used to check the Haskell version of the table against the version in the database, or create the table if none exists... This is for a kind of port of the HaskellDB stuff to ghc, although it is more of a complete reimplementation using the same idea. My aim is to use a monad transformer, so that db operations can be interleaved with other IO. Regards, Keean Schupke.

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RE: linking problems after switching from GHC5 to GHC6
by Simon Marlow 28 Jan '04

28 Jan '04

> I can't link with a library any longer, after switching from ghc5 to > ghc6.2. I've recompiled the library with the new compiler version, so > that's not the problem. [snip] > ghc -o build/test0 build/test0.o -odir build > `src/lib/hsunix-config --local --libs` > build/test0.o(.text+0x25): In function `__stginit_Main_': > : undefined reference to `__stginit_HsUnix_' > build/test0.o(.text+0xec): In function `Main_main_srt': > : undefined reference to `HsUnix_mainwrapper_closure' > build/test0.o(.text+0x151): In function `Main_main_entry': > : undefined reference to `HsUnix_mainwrapper_closure' > collect2: ld returned 1 exit status > make: *** [build/test0] Error 1 > rm build/test0.o Strange. Could you send us the output from -v? Cheers, Simon

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RE: Generics...(ish)
by Simon Peyton-Jones 28 Jan '04

28 Jan '04

Try the new stuff (in GHC6.2) in the Data.Generics library. In particular the class Data, and its related types Constr and DataType http://www.haskell.org/ghc/docs/latest/html/libraries/base/Data.Generics .Basics.html Ralf and I are writing a paper about the extensions you'll find there, which aren't in our original "scrap your boilerplate" paper. Simon | -----Original Message----- | From: glasgow-haskell-users-bounces(a)haskell.org [mailto:glasgow-haskell-users- | bounces(a)haskell.org] On Behalf Of MR K P SCHUPKE | Sent: 21 January 2004 12:35 | To: glasgow-haskell-users(a)haskell.org | Subject: Generics...(ish) | | | I am currently using template haskell to generate code to work on a | record data type... This however is not very pretty, and I wondered if | there was another way to do what I want in GHC. I need to iterate over | the contents of a record for example: | | data Test = Test { a :: Int, b :: String, c :: Float } | | If I derive Typeable, I can compare the data-type, but not decompose it, | I don't know much about generics, and was wondering if I might be able to | do it that way... | | The functionality I need is equivalent to being able to compare to instances, | for example, consider the type above, and the type below: | | data Test2 = Test2 { x :: Int, y :: String, z :: Float, zz :: String } | | i need to construct a function that could output the differenc between the | types, position at a time, so for the above the output would be: | | Test2 contains extra String field. | | or if "y" was to have the type Float, | | Position 2 : Types differ (Test has String, Test2 has Float) | Test2 contains extra String field. | | | I could do this easily if Typeable was a concrete type just by using | case statements... | | Regards, | Keean Schupke. | _______________________________________________ | Glasgow-haskell-users mailing list | Glasgow-haskell-users(a)haskell.org | http://www.haskell.org/mailman/listinfo/glasgow-haskell-users

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RE: "Talking" with the compiler
by Simon Peyton-Jones 28 Jan '04

28 Jan '04

| Yes, the HEP was one attempt to define the interface. There was a | "HEP-lite" implementation at one point, I believe, but it was never | fully adopted. But in effect, GHCi-as-a-library amounts to a HEP expressed as a Haskell library rather than a COM object. So we're getting there. S

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RE: Problem with ghc on Windows ME
by Simon Marlow 28 Jan '04

28 Jan '04

We looked into this issue today (without access to a Win98/ME box though). The conclusion, I think, is that: - rawSystem is wrongly escaping backslashes before executing the command. - NT-derived flavours of Windows are more forgiving than Win95-derived Windows when it comes to multiple backslashes used as directory separators. There's an easy fix (patch attached). If anyone would like to test the patch and let us know if it helps, that would be greatly appreciated. Cheers, Simon

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