- Hugs-Users - Haskell.org

ANNOUNCE: Hugs 98 January 2001 beta
by Johan Nordlander 02 Feb '01

02 Feb '01

================================================================== __ __ __ __ ____ ___ || || || || || || ||__ ||___|| ||__|| ||__|| __|| ||---|| ___|| || || || || Version: January 2001 beta ================================================================== Dear all, I'm pleased to announce the availability of a new beta release of Hugs98. This is a beta release that aims at giving as many people as possible a chance to react to the changes and additions that have recently been incorporated, before the next major version is released on February 14 2001. A list of the most important new features looks as follows: - A Foreign Function Interface closely modelled after the one provided by GHC. - Built-in, Hood-like debugging support. - A new syntax for recursive monad bindings. - A new GUI under Windows that doesn't consume all CPU time. See the release notes in the "docs" directory of the distribution for more information on some of these features. Send email to hugs-users-request(a)haskell.org to join the hugs-users mailing list. Bug reports should be sent to hugs-bugs(a)haskell.org. Send email to hugs-bugs-request(a)haskell.org to subscribe to the hugs-bugs list. The home page and download site for Hugs is at http://www.haskell.org/hugs/ Enjoy, Johan Nordlander PS Please don't confuse this release with latest (January 31) release of a new version of O'Hugs, the O'Haskell interpreter!

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Re: tail recursion
by S. Doaitse Swierstra 23 Jan '01

23 Jan '01

Using the combinators at: http://www.cs.uu.nl/groups/ST/Software/UU_Parsing the problem is solved by (see also the file demo.hs there): pLetter = pAnyOf "abcdefghijklmnopqrstuvwxyz" pString = pList pLetter pAll elems = foldr ((*>) . pSym) (pSucceed []) elems pRoot keys = pString <* pPacked (pSym '<') (pSym '>') (foldr (<|>) pFail (map pAll keys)) <* pString Doaitse Swierstra PS: small modifications may be needed depending on what you want to do with the part after the keyword At 01:24 -0500 2/8/00, Christopher Sharpe wrote: >Hello, > >Thanks to those who pointed out that my previous function p was not tail >recursive. >I think "exclude" (below) is. It seems to work on large files, although >on a 160K >file garbage collection fails to get enough space. > >What I am trying to do is find, in input such as an HTML file, like >"ab<table>c", >the string before the keyword such as "table". So I try the keyword >parsers >(in the list "ps" below) at each point in the input, and add the >character to >my answer if all the parsers fail. Something like a Boyer-Moore string >search might >be used to, though that would add complexity. I couldn't find such an >algorithm >in any Hugs library. > >---------------------------- program ----------------------------- > >import ParseLib > >exclude ans parsers = P (\inp -> case inp of > [] -> [(reverse ans,"")] > (c:cs) -> case papply try inp of > [(_,remaining)] -> [(reverse ans,remaining)] > [] -> papply (exclude >(c:ans) parsers) cs > ) > where try = commonSubstring >> foldr1 (+++) parsers > > >test = papply (exclude "" ps) "ab<table>c" > >commonSubstring = string "<" > >ps = [string "table>",string "/table>" ] >Content-Type: Haskell; > name="ww.hs" >Content-Transfer-Encoding: 7bit >Content-Disposition: inline; > filename="ww.hs" > >Attachment converted: Doaitse:ww.hs 2 (????/----) (00006585) -- __________________________________________________________________________ S. Doaitse Swierstra, Department of Computer Science, Utrecht University P.O.Box 80.089, 3508 TB UTRECHT, the Netherlands Mail: mailto:doaitse@cs.uu.nl WWW: http://www.cs.uu.nl/ PGP Public Key: http://www.cs.uu.nl/people/doaitse/ tel: +31 (30) 253 3962, fax: +31 (30) 2513791 __________________________________________________________________________

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Re: Finalizer problems..
by mpringle＠sfu.ca 17 Jan '01

17 Jan '01

Didn't ghc 4.08-1 just come out in the last couple of months or so? Maybe there have been some bug fixes that deal with this. Of course, maybe not. cheers, Micha On Wed, 17 Jan 2001 03:08:48 -0800 simonmar(a)microsoft.com wrote: > > > I would like to run some code when something is > > > garbage-collected. Fine, he says, just the job for > > > finalizers (module Weak). Unfortunately, they don't > > > seem to offer a general solution, as the code below > > > demonstrates (presumably, smallish things are copied, > > > not shared, so that the finalizers run too early?). > > > > Yes, small Ints (approximately 30 bits worth) and Chars have a special > > representation which makes it impossible to tell if they have > > been GC'd > > > > GHC has a similar problem for Chars and small ints (-15..15 I think). > > GHC has similar problems for just about all types, due to agressive > inlining and other optimisations. We've found that the only reliable > types on which you can set a finalizer are the primitive heap-resident > ones, like ForeignObj# and MutVar#. That's why using > addForeignFinalizer is better than using the generic addFinalizer. > > We dreamed up various hacks to subvert the optimisations, but haven't > found any clean solutions yet. The problem is one of "identity": how to > give an object a name such that you can refer to that particular object. > > Cheers, > Simon > > _______________________________________________ > Hugs-Users mailing list > Hugs-Users(a)haskell.org > http://www.haskell.org/mailman/listinfo/hugs-users

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RE: Finalizer problems..
by Simon Marlow 17 Jan '01

17 Jan '01

> > I would like to run some code when something is > > garbage-collected. Fine, he says, just the job for > > finalizers (module Weak). Unfortunately, they don't > > seem to offer a general solution, as the code below > > demonstrates (presumably, smallish things are copied, > > not shared, so that the finalizers run too early?). > > Yes, small Ints (approximately 30 bits worth) and Chars have a special > representation which makes it impossible to tell if they have > been GC'd > > GHC has a similar problem for Chars and small ints (-15..15 I think). GHC has similar problems for just about all types, due to agressive inlining and other optimisations. We've found that the only reliable types on which you can set a finalizer are the primitive heap-resident ones, like ForeignObj# and MutVar#. That's why using addForeignFinalizer is better than using the generic addFinalizer. We dreamed up various hacks to subvert the optimisations, but haven't found any clean solutions yet. The problem is one of "identity": how to give an object a name such that you can refer to that particular object. Cheers, Simon

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hugs
by Angela kirupairatnam 11 Jan '01

11 Jan '01

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Finalizer problems..
by C.Reinke 11 Jan '01

11 Jan '01

I would like to run some code when something is garbage-collected. Fine, he says, just the job for finalizers (module Weak). Unfortunately, they don't seem to offer a general solution, as the code below demonstrates (presumably, smallish things are copied, not shared, so that the finalizers run too early?). Is there a general way to add finalizers to values of arbitrary type (and have them run when the value, not just one copy of it, disappears)? Or is this behaviour -he hopes- a bug, to be fixed in the next release? Claus ------------- session Main> y nothing is 0 Main> x nothings are (0,0) Main> runAllFinalizers nothing was Main> y 0 Main> x (0,0) ------------- program import IOExts import Weak y = unsafePerformIO $ do { x<-return 0 ; putStrLn "nothing is" ; addFinalizer x (putStrLn "nothing was") ; return x } x = unsafePerformIO $ do { x<-return (0,0) ; putStrLn "nothings are" ; addFinalizer x (putStrLn "nothings were") ; return x }

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(no subject)
by Krprtn＠aol.com 11 Jan '01

11 Jan '01

I have installed Hugs on my PC, could you please tell me how I can configure Hugs to use an editor. The editor I have got installed on my computer is winedt.

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Re: Garbage Collection
by Sigbjorn Finne 12 Dec '00

12 Dec '00

Koen Claessen koen(a)cs.chalmers.se writes: > Hi all, > > I seem to remember some Hugs module with an operation: > > garbageCollection :: IO () > > which cleaned up the memory. Now I need it, but I can't find > it. Did this function ever exist? Yes, the functionality is available via IOExts.performGC --sigbjorn

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http://www.cse.ogi.edu/PacSoft/projects/Hugs/pages/downloading.htm
by dkcombs＠panix.com 11 Dec '00

11 Dec '00

The page mentioned in the subject line talks about downloading a version for LINUX. QUESTION: what about SOLARIS (7)? It says NOTHING about unix *other than* LINUX. Also, what GRAPHICS are available? The book I have is Hudak's, ie all via graphics examples, code, etc. --- Please answer by email, since I am not (yet) signed up for this mailing-list. --- Also, please tell me HOW to sign up for the mailing list. Thanks! David

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Garbage Collection
by Koen Claessen 11 Dec '00

11 Dec '00

Hi all, I seem to remember some Hugs module with an operation: garbageCollection :: IO () which cleaned up the memory. Now I need it, but I can't find it. Did this function ever exist? Koen. -- Koen Claessen http://www.cs.chalmers.se/~koen phone:+46-31-772 5424 mailto:koen@cs.chalmers.se ----------------------------------------------------- Chalmers University of Technology, Gothenburg, Sweden

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