- Glasgow-haskell-users

Re: Qualified identifiers opinion
by Christian Maeder 21 Aug '07

21 Aug '07

Hi Isaac, just to give you a reply at all, see below. I reply glasgow-haskell-users(a)haskell.org since I'm not subscribed to haskell-prime. And I don't want to subscribe, because I'm more interested that Haskell becomes more stable (and standard). So here is my opinion: 1. The lexer should recognize keywords. 2. I would not mind if Haskel98 rejected all keywords that are also rejected by extensions, so that the lexer is extension independent. (Starting with Haskell98, removing conflicting identifiers as soon as I switch on valuable extensions does not make sense.) 3. I'm against qualified identifiers, with the unqualified part being a keyword like "Foo.where". (The choice of qualification should be left to the user, usually one is not forced to used qualified names.) 4. However, "Foo.where" should always be rejected and not changed to "Foo.wher e"! (Longest matching, aka "maximal munch", must not consider keywords!) (see end of: http://www.haskell.org/onlinelibrary/lexemes.html#sect2.4) I would not mind if a name "F. " is plainly rejected. It only makes sense, when a data constructor is the first argument of the composition operator "(.)" Maybe "." and "$" as operators should require white spaces on both sides, since "$(" also indicates template haskell. Cheers Christian Isaac Dupree wrote: > > Especially after writing a partial lexer for Haskell, I opine that this > should be all legal: > > > > module Foo where > > --in case you didn't know, this is legal syntax: > Foo.f = undefined > > Foo.mdo = undefined > Foo.where = undefined > x Foo.! y = undefined > x Foo... y = undefined --remember ".." is reserved id, e.g. [2..5] > > > {-# LANGUAGE RecursiveDo, BangPatterns #-} module Bar where > import Foo > hello !x = mdo { y <- Foo.mdo Foo... ({-Foo.-}f x y); return y } > > {- Haskell 98 -} module Baz where > import Foo > goodbye x = x ! 12 > > > > (Foo.where) lexing as (Foo.wher e) or (Foo . where) does not make me > happy. (being a lexer error is a little less bad...) Especially not > when the set of keywords is flexible. I don't see any good reason to > forbid declaring keywords as identifiers/operators, since it is > completely unambiguous, removes an extension-dependence from the lexer > and simplifies it (at least the mental lexer); Also I hear that the > Haskell98 lexing is (Foo.wher e), which I'm sure no one relies on... > > Well, that's my humble opinion on what should go into Haskell' on this > issue. > > Isaac

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[GHC-as-a-library]getModuleInfo: instances for package module unimplemented
by kenny lu 21 Aug '07

21 Aug '07

Hi all, We've been using to GHC-as-a-library to implement some parts of our project. Our goal is to use ghc to extract necessary type information from Haskell modules. Everything works fine until we attempt to collect the declared type class instances from a packaged haskell module, like List, Monad, etc. The program terminates with an error as follows, getModuleInfo: instances for package module unimplemented We manually trace into the source file /ghc/compiler/main/GHC.hs and find the following snipet of code: getPackageModuleInfo :: HscEnv -> Module -> IO (Maybe ModuleInfo) getPackageModuleInfo hsc_env mdl = do #ifdef GHCI (_msgs, mb_avails) <- getModuleExports hsc_env mdl case mb_avails of Nothing -> return Nothing Just avails -> do eps <- readIORef (hsc_EPS hsc_env) let names = availsToNameSet avails pte = eps_PTE eps tys = [ ty | name <- concatMap availNames avails, Just ty <- [lookupTypeEnv pte name] ] -- return (Just (ModuleInfo { minf_type_env = mkTypeEnv tys, minf_exports = names, minf_rdr_env = Just $! nameSetToGlobalRdrEnv names (moduleName mdl), minf_instances = error "getModuleInfo: instances for package module unimplemented", minf_modBreaks = emptyModBreaks })) It is clearly that the field mind_instances is not assigned to a proper value. Can someone kindly advise on how to implement the missing bit? Or pointing out a workaround? Thank you very much. Best Regards, Kenny Zhuo Ming Lu

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wondering about -ddump-parsed, rn
by Isaac Dupree 20 Aug '07

20 Aug '07

Is ghc -ddump-parsed supposed to give parse-syntactically valid Haskell? It nearly does - the only way I've seen it not do so is infix type-signatures and some infix definitions. Answer: no, look at what it does to the operators with fixities. But, -ddump-rn seems better... file: (@@@) :: a a @@@ b = a + b : a + b ==================== Parser ==================== @@@ :: a @@@ a b = ((a + b) : a) + b ==================== Renamer ==================== @@@ :: a @@@ a b = (a + b) : (a + b) It would be interesting if that was a source-to-source transformation on Haskell: a way to delete all the comments and formatting of the original file. Putting parentheses around infix used as prefix would be nice. Of course... the renamer output depends on other modules, and must for the precise reason of imported fixity declarations! GHC isn't trying to do this so I really have no reason to ask it to :) P.S. this (-ddump-) is a nice way to see how some stages of GHC's processing are done, to get to know them a little, I think, after also looking through some code and Commentary Isaac

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Re: Visual Haskell will not Install with Visual Studio 2005, Express Edition
by Duncan Coutts 20 Aug '07

20 Aug '07

On Thu, 2007-07-26 at 23:51 -0700, Sean Johnson wrote: > Hi Everyone, > > Is there some way to install Visual Haskell with VS2005, Express? > Perhaps some workaround or hack? I believe that free version of VS is specifically designed not to allow any plugins, you have to pay for the the full version for that sadly. As a free alternative, emacs and eclipse have Haskell modes and many other editors have Haskell syntax highlighting. Duncan

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where to take ghc-6.8(.1)
by Serge D. Mechveliani 20 Aug '07

20 Aug '07

Yan Linah wrote about testing ghc-6.8(.1). Please, where to take its source from? If it is CVS, then, please, specify the command. Is it with profiling? ----------------- Serge Mechveliani mechvel(a)botik.ru

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hyperlinked GHC v6.6 grammar (just syntax part)
by Peter Hercek 19 Aug '07

19 Aug '07

Brandon Michael Moore wrote: > How hard is it to make another grammar? It would be very nice if parser > generators could make a page like this. Have you seen the program > BNFC (The BNF Converter)? It tries to generate some nicely-formatted > TeX documentation of the grammar, this could be even more useful. It is not complicated provided that I have a nicely formated EBNF grammar to start with. I agree it would be great if parser generators do this, but there may not be enough interest and I do not have time to do it all myself. I can provide assistance and some code to start with though. Could be worth a license change too. ANTLR generated a hyperlinked grammar description when generating a parser but it does not contain the backward links. When I contacted the authors there was not really an interest there. I checked out the BNFC report. Looks interesting. Though, it was not clear from it whether one can generate hyperlinked html version of the grammar from the TeX source. Do you know it? > No worries there, if there's anything to be sorry about it's depriving > people not on ghc-users of such a nifty. If you really want to apologize > you could make another with the grammar of GHC Haskell :) I added GHC v6.6 grammar. Only the syntax. Check http://www.hck.sk/users/peter/ and the notes at the end of the grammar to see what was changed. Peter.

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ANNOUNCE: Bamse 1.0
by Sigbjorn Finne 17 Aug '07

17 Aug '07

Galois is pleased to announce the first public release of Bamse, a Windows Installer creator framework written in Haskell. Using Bamse, you can easily create applications that let you build Windows Installer (MSIs) for your project's product deliverables. The tool was written quite a while ago (4-5 years) as an internal tool at Galois to help the automated building of shippable bundles for Windows platforms, but has also been used for GHC installers since version 5.0.x (and other Haskell-related tools, interpreters and packages.) The source code + support package is available from http://galois.com/~sof/bamse/ Remarks/notes: - the source code is covered by a BSD license. - questions, bug reports to sof(a)galois.com / sof(a)forkIO.com (*) - If someone would like to adopt and extend the code to make it even more useful, feel free to dive in and hack. (Integrate it into the building of Cabal source and binary dists, perhaps..?) - If there's genuine interest, the code could be made available via a repo ( (*) being the main reason not to right now.) Enjoy --sigbjorn (*) - I'm in the middle of moving to another tectonic plate, so e-mail responses might be slower than usual for the next couple of weeks.

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hyperlinked haskell 98 grammar
by Peter Hercek 16 Aug '07

16 Aug '07

Hi, I was improving my Haskell knowledge lately and I created a small dhtml application which allows browsing of Haskell 98 grammar. I contains both forward and backward hyperlinks. By backward hyperlink I mean that you can click on an a production head and you get a popup list box where you can navigate to any production using the nonterminal. If you like it please save and use your local copy since the server cannot handle much load. http://www.hck.sk/users/peter/ Peter.

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Display problem with ghci (:e) and vim
by Peter Ilberg 16 Aug '07

16 Aug '07

Hello! I've noticed an odd display problem with ghci and vim. The problem occurs with ghci-6.6 and vim-6 on Mac OS X 10.4.9 (Terminal.app and uxrvt in X11.app) and with ghci-6.2.2, ghci-6.6.1 and vim-7.0 on OpenBSD 4.1 (via PuTTY from Windows). 1 - Resize your terminal window to 40 lines. 2 - Start ghci. 3 - :set editor vim 4 - :edit File.hs (pick an existing file) Vim doesn't display the file contents properly in the bottom half of my terminal window (it doesn't display parts of the file). But it does correctly display the : command line at the bottom of the screen. Refreshing the display with Ctrl-L does not help. Infact, it makes things worse in some cases. Resizing the window with the mouse, or by typing resize, or by export LINES=40 does not help either. I don't see this problem under any of these configurations if I use hugs instead of ghci. Has anyone noticed this as well? Is there a workaround? (other than using hugs) Thanks, -- Peter

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Change to deriving in 6.7 ??
by Conal Elliott 16 Aug '07

16 Aug '07

I'm running ghc-6.7.20070802 and getting a new error message that didn't show up with ghc-6.6. Code: -- | Pairing for unary type constructors. newtype Pair1 f g a = Pair1 {unPair1 :: (f a, g a)} deriving (Eq, Ord, Show) Error message: src/Data/Tupler.hs:26:0: No instances for (Show (g a), Show (f a)) arising from the 'deriving' clause of a data type declaration at src/Data/Tupler.hs:(26,0)-(27,25) Possible fix: add an instance declaration for (Show (g a), Show (f a)) When deriving the instance for (Show (Pair1 f g a)) Has there been a change to "deriving"? Is there a workaround? Thanks, - Conal

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