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GHC Out of memory
by John Smith 28 Nov '10

28 Nov '10

I get an out-of-memory error about two thirds of the way through building qtHaskell. If I start again, the remaining modules are compiled successfully, although GHC's memory usage creeps up to about 1.5Gb by the time it's finished. Is there a memory leak? (Compiling on Win64 with 4Gb RAM.)

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qtHaskell signal and slots
by c8h10n4o2 27 Nov '10

27 Nov '10

I have the following code that tries to resize window after a click. But nothing happens. If I use a builtin slot that does not need a function, such as "close", "quit" it works, however for any other slot it seems my function is ignored. Which slot/signal should I use and how? module Main where import Qtc.Classes.Qccs import Qtc.Classes.Gui import Qtc.Gui.Base import Qtc.Gui.QApplication import Qtc.Gui.QPushButton import Qtc.Core.QFile import Qtc.Tools.QUiLoader import Qtc.Enums.Core.QIODevice import Qtc.Core.Base import Qtc.ClassTypes.Gui import Qtc.Gui.QAbstractButton main = do app <- qApplication () loader <- qUiLoader () uiFile <- qFile "slide.ui" open uiFile fReadOnly ui <- load loader uiFile close uiFile () add <- findChild ui ("<QPushButton*>", "pushButton") connectSlot add "clicked()" add "click()" $ t ui qshow ui () qApplicationExec () t :: QWidget () -> QWidget () -> IO () t ui _= resize ui (500::Int ,500::Int) -- View this message in context: http://haskell.1045720.n5.nabble.com/qtHaskell-signal-and-slots-tp3282748p3… Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com.

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Is EclipseFP alive?
by Dušan Kolář 27 Nov '10

27 Nov '10

Hello, I tried to install EclipseFP using instructions on http://eclipsefp.sourceforge.net/, nevertheless, without any success - after downloading scion I cannot build it > cabal install Resolving dependencies... cabal: dependencies conflict: ghc-6.12.3 requires Cabal ==1.8.0.6 however Cabal-1.8.0.6 was excluded because scion-0.1.0.6 requires Cabal ==1.6.* Running Setup.hs through runhaskell seems not to work as well: > runhaskell Setup.hs configure Configuring scion-0.1.0.6... Setup.hs: At least the following dependencies are missing: AttoJson >=0.5.2, binary ==0.5.*, derive -any, ghc-paths ==0.1.*, ghc-syb -any, ghc-syb-utils -any, hslogger ==1.0.*, list-tries -any, multiset >=0.1 && <0.3, uniplate -any Even if, for instance: > cabal info binary * binary (library) Synopsis: Binary serialisation for Haskell values using lazy ByteStrings Latest version available: 0.5.0.2 Latest version installed: 0.5.0.2 Is there any chance to make it install or should I give up? Dusan

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Language.C++ ?
by Jacques Carette 27 Nov '10

27 Nov '10

Is anyone working on a Language.C++ module, similar to the wonderful Language.C ? Right now just the syntax and a pretty-printer would be really nice to have... Jacques

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Re: Template Haskell: exchanging information between 'splicers'
by oleg＠okmij.org 27 Nov '10

27 Nov '10

Jean-Christophe Mincke wrote: > Does anyone know a clean solution to pass information between 2 executions > of splicers. > > $(splicer ....) -- first invocation gather and store some data > .... > $(splicer ...) -- second one use the data gathered above. Just the other day I wrote such code; I'm not sure it qualifies as a `clean solution' as it was meant for a nefarious purpose. > e2 = runIO $ do > varref <- newIORef undefined > let put v = runIO $ do > putStrLn "put" > writeIORef varref v > runQ [|$v + 1|] > let get v = runIO $ do > putStrLn "get" > vold <- readIORef varref > runQ [|$v + $vold|] > > c1 <- runQ [|\x -> $(put [|x|]) + 1::Int|] > c2 <- runQ [|\x -> $(get [|x|]) + 1::Int|] > runQ $ [| ($(return c1),$(return c2)) |] > > show_code cde = runQ cde >>= putStrLn . pprint > te2 = show_code e2 One may even try to splice e2 at the top level (in a different module). The code does exchange data between two splicers -- one may argue, it exchanges too much data.

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version of findIndex that works with a monadic predicate
by José Romildo Malaquias 27 Nov '10

27 Nov '10

Hello. I need a function findIndexM, similar to findIndex from the standard module Data.List, but which works with a monadic predicate to test list elements. findIndex :: (a -> Bool) -> [a] -> Maybe Int findIndexM :: (Monad m, Num a) => (t -> m Bool) -> [t] -> m (Maybe a) findIndexM p xs = go 0 xs where go _ [] = return Nothing go n (x:xs) = do res <- p x if res then return (Just n) else go (n+1) xs How can this function be rewritten using combinators? Romildo

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Plot Haskell functions in TikZ
by Henning Thielemann 27 Nov '10

27 Nov '10

I'd like to draw function graphs in a LaTeX document. I'm using PGF/TikZ that allows to interact with gnuplot, but it does not use gnuplot as plotter but just for function evaluation. And gnuplot is not very good at this, it does not even know 'min' or 'max'. pgfmanual.pdf says, that in the TikZ you can write in a tikzpicture environment: --plot[local options] function {gnuplot formula} This command does two things: 1. It writes a gnuplot script containing the formula to a file like plot-name.gnuplot . 2. It checks for a data table in plot-name.table and displays the contained curve. Outside of LaTeX, say in a Makefile, you call gnuplot in order to run plot-name.gnuplot and receive plot-name.table: %.table: %.gnuplot gnuplot $< Now you can easily guess, what I want to do. I like to write a Haskell formula in '--plot' and get a Haskell program, that renders the table. The LaTeX macro invocation should look like: --plot[local options] haskellfunction {haskell formula} The Make rule should look like: %.table: %.hs runhaskell $< Has anyone tried to write such a '--plot' command for TikZ?

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Template Haskell: exchanging information between 'splicers'
by jean-christophe mincke 26 Nov '10

26 Nov '10

Hello, Does anyone know a clean solution to pass information between 2 executions of splicers. Ex. $(splicer ....) -- first invocation gather and store some data .... $(splicer ...) -- second one use the data gathered above. Thank you Regards J-C

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How to instance class with functional dependency?
by Magicloud Magiclouds 26 Nov '10

26 Nov '10

Hi, In System.Posix.IOCtl, there is such a class: class Storable d => IOControl req d | req -> d where ioctlReqSource :: req -> CInt How to instance it? I do it as: data TIOCGWINSZ = TIOCGWINSZ #starttype struct winsize #field ws_row , CUShort #field ws_col , CUShort #field ws_xpixel , CUShort #field ws_ypixel , CUShort #stoptype instance IOControl TIOCGWINSZ C'winsize where ioctlReq _ = #const TIOCGWINSZ Then I got: topIO.hs:19:0: Couldn't match expected type `C'winsize' against inferred type `Int' When using functional dependencies to combine IOControl (Foreign.C.Types.CUShort -> Foreign.C.Types.CUShort -> Foreign.C.Types.CUShort -> Foreign.C.Types.CUShort -> C'winsize) Int, arising from a use of `ioctl'' at topIO.hs:21:35-60 IOControl (Foreign.C.Types.CUShort -> Foreign.C.Types.CUShort -> Foreign.C.Types.CUShort -> Foreign.C.Types.CUShort -> C'winsize) C'winsize, arising from a use of `ioctl'' at topIO.hs:20:12-37 When generalising the type(s) for `main' -- 竹密岂妨流水过山高哪阻野云飞

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Eq instance for Chan
by Mitar 25 Nov '10

25 Nov '10

Hi! Why is there no Eq instance for Chan? There is Eq for MVar so it is quite possible to define also Eq for Chan? What I would like to do is keep track how many consumers I have for each Chan so duplicating them with dupChan as necessary. So I was thinking of storing a list of Chans which already have a consumer and then duplicating it if another (and every additional) consumer would be added. But without Eq it is not possible to check if there is Chan already in a list (and I hope Eq would compare just Chan and not its content). Is there some other way to achieve this? Mitar

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