----- Original Message ----
From: "haskell-cafe-request@haskell.org" <haskell-cafe-request@haskell.org>
To: haskell-cafe@haskell.org
Sent: Thursday, September 25, 2008 12:13:22 PM
Subject: Haskell-Cafe Digest, Vol 61, Issue 49

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Today's Topics:

  1. RE: Injecting Haskell into C (Simon Peyton-Jones)
  2. Re: Haskell board game (Ryan Ingram)
  3. Re: Am I doing it right? (Achim Schneider)
  4. Re: if - then - else layout (Jules Bean)
  5. Re: if - then - else layout (Achim Schneider)
  6. Re: Distributing Haskell binaries as OSX App Bundles
      (Christian Maeder)
  7. Re: if - then - else layout (Achim Schneider)
  8. Re: if - then - else layout (Achim Schneider)
  9. announcing darcs 2.1.0pre2 (Eric Kow)
  10. Re: pure Haskell database (jean-christophe mincke)
  11. Re: pure Haskell database (Achim Schneider)
  12. Re: pure Haskell database (Marc Weber)
  13. Re[2]: [Haskell-cafe] pure Haskell database (Bulat Ziganshin)
  14. Re: Google Android (Adam Langley)
  15. Re: Google Android (Maarten Hazewinkel)
  16. Where is OpenGL loadMatrix ? (minh thu)
  17. Re: Where is OpenGL loadMatrix ? ( Krzysztof Skrz?tnicki )
  18. Re: Where is OpenGL loadMatrix ? (Achim Schneider)
  19. Re: Re: Where is OpenGL loadMatrix ? (minh thu)
  20. StateWriter: a monad-writing exercise (Anthony LODI)
  21. Re: StateWriter: a monad-writing exercise (Henning Thielemann)
  22. Re: Re: Where is OpenGL loadMatrix ? (Bit Connor)
  23. Re: Re: Where is OpenGL loadMatrix ? (minh thu)
  24. Re: Where is OpenGL loadMatrix ? (Achim Schneider)
  25. Re: pure Haskell database (Manlio Perillo)
  26. Microsoft's Craig Mundie outlines the future of    computing
      (Lihn, Steve)
  27. GHC 6.10, OS X, Fink and CPPFLAGS (Svein Ove Aas)
  28. Re: Climbing up the shootout... (Ketil Malde)
  29. Problem with existential quantification (Eric)


----------------------------------------------------------------------

Message: 1
Date: Thu, 25 Sep 2008 08:32:44 +0100
From: Simon Peyton-Jones <simonpj@microsoft.com>
Subject: RE: [Haskell-cafe] Injecting Haskell into C
To: Anatoly Yakovenko <aeyakovenko@gmail.com>,    "roma@ro-che.info"
    <roma@ro-che.info>
Cc: haskell <haskell-cafe@haskell.org>
Message-ID:
    <638ABD0A29C8884A91BC5FB5C349B1C32D766E2F96@EA-EXMSG-C334.europe.corp.microsoft.com>
   
Content-Type: text/plain; charset="us-ascii"

Anatoly

I have not been following the details, but would you consider writing up your example on the GHC user guide Wiki?
        http://haskell.org/haskellwiki/GHC/Using_the_FFI

It's a very good way to share your experience with others.

Simon

| -----Original Message-----
| From: haskell-cafe-bounces@haskell.org [mailto:haskell-cafe-
| bounces@haskell.org] On Behalf Of Anatoly Yakovenko
| Sent: 24 September 2008 22:42
| To: roma@ro-che.info
| Cc: haskell
| Subject: Re: [Haskell-cafe] Injecting Haskell into C
|
| you'll find this example really helpfull
|
|
| ---------- Forwarded message ----------
| From: Claude Heiland-Allen <claudiusmaximus@goto10.org>
| Date: 2008/6/5
| Subject: Re: [Haskell-cafe] example of FFI FunPtr
| To: "Galchin, Vasili" <vigalchin@gmail.com>
| Cc: haskell <haskell-cafe@haskell.org>
|
|
| Galchin, Vasili wrote:
| >
| > Hello,
| >
| >      I want to model a Haskell function that is a callback from C. I have
| > only found one example in the unix package's Semaphore.hsc, which
| apparently
| > is not used. I want to be able to marshall a Haskell function that is a
| > first class citizen residing in a Haskell data type and pass to a C
| function
| > via FFI. Are there examples of this?
|
| Attached is a simple example.
|
| The main thing to note is 'foreign import ccall "wrapper"' which gives
| you a factory for turning Haskell functions into foreign function
| pointers.
|
| More information:
|
| http://www.cse.unsw.edu.au/~chak/haskell/ffi/
|
|
| Claude
| --
| http://claudiusmaximus.goto10.org
|
|
| CallBacker: CallBacker.hs callerback.c callerback.h
|        ghc -O2 -Wall -fffi -o CallBacker CallBacker.hs callerback.c
|
| _______________________________________________
| Haskell-Cafe mailing list
| Haskell-Cafe@haskell.org
| http://www.haskell.org/mailman/listinfo/haskell-cafe


------------------------------

Message: 2
Date: Thu, 25 Sep 2008 01:09:02 -0700
From: "Ryan Ingram" <ryani.spam@gmail.com>
Subject: Re: [Haskell-cafe] Haskell board game
To: "Rafael C. de Almeida" <almeidaraf@gmail.com>
Cc: haskell-cafe@haskell.org
Message-ID:
    <2f9b2d30809250109g3f0a2359s31a003c515549875@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1

Bertram has put together a peg solitaire game using gtk2hs with Prompt
for control:
    http://int-e.home.tlink.de/haskell/solitaire.tar.gz

It's a good read and probably a good starting point for other board games.

  -- ryan

On Wed, Sep 24, 2008 at 7:04 PM, Rafael C. de Almeida
<almeidaraf@gmail.com> wrote:
> Hello,
>
> I'm interested in doing a simple board game on haskell. For that I want
> to be able to draw stuff like the possible player movements and I want
> to be able to display very simple animations. I want to know what
> graphical interface library you suggest to me.
>
> I have almost no prior experience with graphical interfaces of any kind,
> so I rather start with something easy and straightforward. I have no
> need for great performance or anything like that. I'd like if it runs on
> windows with much trouble, that is, it'll be easy to package it for
> windows without requiring the user to install anything besides my game.
>
> My first thought was to use GTK's gtkTable, but I'm unsure how easy it
> is to make it work on windows. Beside that, I'm not sure it would be the
>  easiest API for me to use.
>
> []'s
> Rafael
> _______________________________________________
> Haskell-Cafe mailing list
> Haskell-Cafe@haskell.org
> http://www.haskell.org/mailman/listinfo/haskell-cafe
>


------------------------------

Message: 3
Date: Thu, 25 Sep 2008 10:41:38 +0200
From: Achim Schneider <barsoap@web.de>
Subject: [Haskell-cafe] Re: Am I doing it right?
To: haskell-cafe@haskell.org
Message-ID: <20080925104138.02079514@solaris>
Content-Type: text/plain; charset=US-ASCII

Daniel Fischer <daniel.is.fischer@web.de> wrote:
> The fast searching function on ByteStrings has already been written
> for you :)
>
That's in ghc 6.8.3, which is not in gentoo but only in the haskell
overlay, which means that all blame goes to the gentoo maintainers for
being utterly out of date.

The KMP import works like a charm.

findSubstring is only defined for strict bytestrings... try
running those benchmarks again, this time on data bigger than your ram.
Not to mention that it's deprecated.

The really interesting topic is hacking Parsec to use KMP search on
"manyTill anyChar (try string match), or rather any recursive try
involving combinators that can calculate the position for the next
candidate match as a side effect.

PS: Thank you for not pointing out that my original code crashes on
B.tail B.empty in some cases, or even just that it can't replace
overlapping matches at all.

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------------------------------

Message: 4
Date: Thu, 25 Sep 2008 09:45:12 +0100
From: Jules Bean <jules@jellybean.co.uk>
Subject: Re: [Haskell-cafe] if - then - else layout
To: leledumbo <leledumbo_cool@yahoo.co.id>
Cc: haskell-cafe@haskell.org
Message-ID: <48DB4F98.9000804@jellybean.co.uk>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

leledumbo wrote:
> consider this partial program:
> if n>5 then
>  putStrLn "big"
> else
>  putStrLn "small"
>
> this works fine in hugs, but in ghc I must change it to:
> if n>5
>  then
>    putStrLn "big"
>  else
>    putStrLn "small"

Actually both of those are valid expressions.

And they both work in hugs and ghc.

The question I imagine you're asking involves layout mode:

do
  if n>5 then
    putStrLn "big"
  else
    putStrLn "small"

this is shorthand for

do { if n > 5 then putStrLn "big" ; else putStrLn "small" }

which is a syntax error. A statement in a do block cannot begin with the
keyword "else".

If you indent the else a bit further than it counts and a continuation
of the enclosing expression (beginning with if) so it desugars to

do { if n > 5 then putStrLn "big" else putStrLn "small" }

which is fine.

Haskell' is apparently going to include a hack to permit this case. I
think that's a poor decision, because including a hack to the layout
rule makes it harder to understand and explain the layout rule.

Jules


------------------------------

Message: 5
Date: Thu, 25 Sep 2008 10:48:21 +0200
From: Achim Schneider <barsoap@web.de>
Subject: [Haskell-cafe] Re: if - then - else layout
To: haskell-cafe@haskell.org
Message-ID: <20080925104821.09da2a93@solaris>
Content-Type: text/plain; charset=US-ASCII

"Brandon S. Allbery KF8NH" <allbery@ece.cmu.edu> wrote:

> I think Hugs is violating the Haskell98 layout rules.
>
One could argue that GHC should, too.

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------------------------------

Message: 6
Date: Thu, 25 Sep 2008 11:04:00 +0200
From: Christian Maeder <Christian.Maeder@dfki.de>
Subject: [Haskell-cafe] Re: Distributing Haskell binaries as OSX App
    Bundles
To: Stephen <analytic@gmail.com>
Cc: Haskell-Cafe@haskell.org
Message-ID: <48DB5400.4060804@dfki.de>
Content-Type: text/plain; charset=ISO-8859-1

Stephen wrote:
> I wrote a command-line program recently for a friend in haskell.
> However, he's far away and not particularly computer literate.  I sent
> him the raw binaries, but they came up with errors about not being able
> to find libgmp stuff.  So then I thought I should probably be able to

I usually link in libgmp.a statically. This happens automatically if
libgmp.a resides in ghc's libdir (just copy it)

Cheers Christian


------------------------------

Message: 7
Date: Thu, 25 Sep 2008 11:12:26 +0200
From: Achim Schneider <barsoap@web.de>
Subject: [Haskell-cafe] Re: if - then - else layout
To: haskell-cafe@haskell.org
Message-ID: <20080925111226.67482196@solaris>
Content-Type: text/plain; charset=US-ASCII

Jules Bean <jules@jellybean.co.uk> wrote:

> do
>    if n>5 then
>      putStrLn "big"
>    else
>      putStrLn "small"
>
> this is shorthand for
>
> do { if n > 5 then putStrLn "big" ; else putStrLn "small" }
>
> which is a syntax error. A statement in a do block cannot begin with
> the keyword "else".
>
> Haskell' is apparently going to include a hack to permit this case. I
> think that's a poor decision, because including a hack to the layout
> rule makes it harder to understand and explain the layout rule.
>
There's no need to hack the layout rule, you're even giving pointers to
the solution. Something like this:

if p = do
    (_, c, a) <- get
    put (b, c, a)
    mzero

then c = do
    (b, _, a) <- get
    put (b, c, a)
    mzero

else a = do
    (b, c, _) <- get
    put (b, c, a)
    mzero

end = do
    (b, c, a) <- get
    return if p then a else c

Advantages are obvious: Order doesn't really matter anymore, as in

then "get away"
else "or else"
if i tell you to
end

Furthermore, this scheme supports logical comments, a rare kind of
control structure enabling mindboggingly diverse rapid prototyping
options:

if i knew what i want to do
if i knew how to do it
then i'd have written the next line much earlier
if i wrote this line
then i don't need to remove the other lines
else where in other languages i'd have to do that
end

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------------------------------

Message: 8
Date: Thu, 25 Sep 2008 11:20:58 +0200
From: Achim Schneider <barsoap@web.de>
Subject: [Haskell-cafe] Re: if - then - else layout
To: haskell-cafe@haskell.org
Message-ID: <20080925112058.46e0c095@solaris>
Content-Type: text/plain; charset=US-ASCII

Achim Schneider <barsoap@web.de> wrote:

> if i knew how to do it

Sorry, apparent mistake, besides confusing b (bool) with p (predicate):

if p _ c = do
    (_, _, a) <- get
    put (p, c, a)
    mzero

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------------------------------

Message: 9
Date: Thu, 25 Sep 2008 10:32:27 +0100
From: Eric Kow <kowey@darcs.net>
Subject: [Haskell-cafe] announcing darcs 2.1.0pre2
To: darcs-users@darcs.net
Cc: haskell-cafe@haskell.org
Message-ID: <20080925093227.GG301@Macintosh.local>
Content-Type: text/plain; charset="utf-8"

Hi everybody,

The second pre-release of darcs 2.1 (formerly known as 2.0.3) is now
available at http://darcs.net/darcs-2.1.0pre2.tar.gz

We have increased the version number since the last pre-release because
we are adopting an important new behaviour:

  The darcs initialize command now creates darcs-2 format
  repositories by default

This will help new repositories to benefit from the improved handling of
duplicate patches and to avoid the exponential time conflicts problem.

Upcoming release schedule
-------------------------
2008-10-03: darcs 2.1.0pre3
2008-10-10: darcs 2.1.0

Work remaining
--------------
* http://bugs.darcs.net/issue971 (Petr Ročkai)
  When using hashed or repositories, allow darcs check to deal with filenames
  that differ only in case when run on a case-insensitive filesystem.  Petr
  has done 90% of the work for this -- he has implemented this for darcs
  repair -- so this shall largely be a question of refactoring.

* http://bugs.darcs.net/issue1003
  Allow darcs-transfer mode to deal with a specific set of missing files
  (namely _darcs/format) so that users can benefit from ssh connection
  sharing even if the remote end uses an old-fashioned repository.  In
  the meantime, a simple workaround is to touch the _darcs/format file in
  the remote repoistory
 
* http://bugs.darcs.net/issue1078
  Fix a corner case in paths handling that makes darcs overly
  cautious if the repository is a symbolic link

* http://bugs.darcs.net/issue1026
  Improve the error messages for 'bug in get_extra' errors, which can
  happen if darcs is fooled into thinking that two patches are the same.

Changes since the last pre-release
----------------------------------
* User Experience: Do not allow users to add files to a darcs repository if
  their filenames would be considered invalid under Windows. This can be
  overridden with the --reserved-ok flag (issue53, Eric Kow)

* Bug Fix: Do not leave behind a half-gotten directory if darcs get fails
  (issue1041, Vlad Dogaru, David Roundy)

* User Experience: notice when you are trying to pull from a seemingly
  unrelated repository, that is one with a sufficiently different history.
  This can be overridden with the --allow-unrelated-repos flag (Dmitry
  Kurochkin, David Roundy)

* Bug Fix: Fix hang after a user input error (for example, EOF) (Judah
  Jacobson)

* Quality Assurance: Improvements to documentation and online help (Simon
  Michael)

--
Eric Kow <http://www.nltg.brighton.ac.uk/home/Eric.Kow>
PGP Key ID: 08AC04F9
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------------------------------

Message: 10
Date: Thu, 25 Sep 2008 11:52:26 +0200
From: "jean-christophe mincke" <jeanchristophe.mincke@gmail.com>
Subject: Re: [Haskell-cafe] pure Haskell database
To: "Marc Weber" <marco-oweber@gmx.de>, haskell-cafe@haskell.org
Message-ID:
    <c0727ea70809250252gb1ea978j661df85f79a529b1@mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"

Marc

What is this strange syntax

columns = [ ("trackId", conT *''Int* )

It looks like a not ended string literal unless I still have sth to learn
about Haskell.

Thank you

J-C



On Thu, Sep 25, 2008 at 12:03 AM, Marc Weber <marco-oweber@gmx.de> wrote:

> On Wed, Sep 24, 2008 at 11:17:01PM +0200, Manlio Perillo wrote:
> >  Hi.
> >
> >  I need a simple, concurrent safe, database, written in Haskell.
> >  A database with the interface of Data.Map would be great, since what I
> need
> >  to to is atomically increment some integer values, and I would like to
> avoid
> >  to use SQLite.
>
> I've tried writing at least part of that. But it's still higly
> experimental and uses template haskell.
> It looks like this:
> from that some datastructures are defined which look like
> tables used in traditional RDBMS such as SQLite..
> However if you don't want to use many "tables" you may be a lot faster
> writing down what you need yourself. My lib automacially generates code
> for inserting / deleting tuples into multi indexes such as (Map Int (Map
> Int PrimIdx)).
>
> $(let cds = defaultTable {
>                tblName = "cds"
>                , columns = [ ("cdId", conT ''Int) , ("title", conT ''Int) ]
>                , primary = PrimaryUniq [ "cdId" ] [| 0 |]
>                , indexes = [ Index "title" [] ]
>                , tblStates = [ ( "nextCdId", [t| Int |], [| 0 |] ) ]
>            }
>
>      tracks = let
>            a="a"
>            -- updateNumRows n = [| \n -> cdUpdateByPK (\r -> r {
> num_tracks = (num_tracks r) + $(n) } ) |]
>            in defaultTable {
>            tblName = "tracks"
>            , columns = [ ("trackId", conT ''Int )
>                      , ("name", conT ''String)
>                      , ("cd", conT ''Int) -- foreign key
>                      ]
>            , primary = PrimaryUniq [ "cd", "trackId" ] [| 0 |]
>            , indexes = [ Index "cd" [ IndexUnique "trackId" ] ] --the id
> is uniq foreach cd
>            -- checks = [ foreignConstraint "cd" "cds" "id" ]
>            -- triggers =  [ InsertUpdate  (Just ["cd"]) [| cdUpdateByPK (
> updateNum_tracks (+1) ) . pk |]
>                          -- DeleteUpdate  (Just ["cd"]) [| cdUpdateByPK (
> updateNum_tracks (-1) ) . pk |]
>                          -- ]
>                }
>      db = defaultDB {
>              dbName = "my"
>            , tables = [ cds, tracks]
>            , statistics = True
>            }
>  in createDB db)
>
>
> If you're interested drop me a mail.
>
> Marc
> _______________________________________________
> Haskell-Cafe mailing list
> Haskell-Cafe@haskell.org
> http://www.haskell.org/mailman/listinfo/haskell-cafe
>
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------------------------------

Message: 11
Date: Thu, 25 Sep 2008 12:08:28 +0200
From: Achim Schneider <barsoap@web.de>
Subject: [Haskell-cafe] Re: pure Haskell database
To: haskell-cafe@haskell.org
Message-ID: <20080925120828.09fec80f@solaris>
Content-Type: text/plain; charset=US-ASCII

"jean-christophe mincke" <jeanchristophe.mincke@gmail.com> wrote:

> What is this strange syntax
>
> columns = [ ("trackId", conT *''Int* )
>
> It looks like a not ended string literal unless I still have sth to
> learn about Haskell.
>
' isn't special in Haskell, it's idiomatic: you often see things like

foo' = bar foo

, as mathematicians and haskellers are to lazy to think of a new name
for foo just because they got a derived foo.

I, too, have no idea what *''Int* means. It's part of the "just use the
*&%*$^!#!$%!^ operator" problem.

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Message: 12
Date: Thu, 25 Sep 2008 12:31:44 +0200
From: Marc Weber <marco-oweber@gmx.de>
Subject: Re: [Haskell-cafe] pure Haskell database
To: haskell-cafe@haskell.org
Message-ID: <20080925103144.GA18833@gmx.de>
Content-Type: text/plain; charset=utf-8

On Thu, Sep 25, 2008 at 11:52:26AM +0200, jean-christophe mincke wrote:
>    Marc
>
>    What is this strange syntax
>
>    columns = [ ("trackId", conT ''Int )

Hi J-C,

I'ts part of template haskell and tells ghc to use the type
referenced by Int. There are some getting started guides on haskell.org
By the way you can enhance readability of your messages if you only keep
that part of the message you're refering to.

Sincerly
Marc Weber


------------------------------

Message: 13
Date: Thu, 25 Sep 2008 14:48:12 +0400
From: Bulat Ziganshin <bulat.ziganshin@gmail.com>
Subject: Re[2]: [Haskell-cafe] pure Haskell database
To: "jean-christophe mincke" <jeanchristophe.mincke@gmail.com>
Cc: haskell-cafe@haskell.org
Message-ID: <988210512.20080925144812@gmail.com>
Content-Type: text/plain; charset=us-ascii

Hello jean-christophe,

Thursday, September 25, 2008, 1:52:26 PM, you wrote:

>  columns = [ ("trackId", conT ''Int )

> It looks like a not ended string literal unless I still have sth to learn about Haskell.

it's TemplateHaskell, look for Reification in http://www.haskell.org/bz/thdoc.htm


--
Best regards,
Bulat                            mailto:Bulat.Ziganshin@gmail.com



------------------------------

Message: 14
Date: Thu, 25 Sep 2008 04:33:09 -0700
From: "Adam Langley" <agl@imperialviolet.org>
Subject: Re: [Haskell-cafe] Google Android
To: "Galchin, Vasili" <vigalchin@gmail.com>
Cc: "haskell-cafe@haskell.org" <haskell-cafe@haskell.org>
Message-ID:
    <396556a20809250433n75d817bfr30847a0fe6334ff@mail.gmail.com>
Content-Type: text/plain; charset=UTF-8

2008/9/24 Galchin, Vasili <vigalchin@gmail.com>:
>    Do there currently (or in the works) exist FFI bindings for Google's
> Android API?

The Android API is obviously a Java API, additionally Android will
only execute DEX bytecode programs, so you would first need a way to
compile Haskell to Java, Java bytecode or DEX directly. A Google
search for "haskell java" turns up at least one good candidate[1], but
if you manage to get that working well, binding the APIs is a rather
trivial task ;)


[1] http://www.cse.unsw.edu.au/~pls/thesis-topics/ghcjava.html

AGL

--
Adam Langley agl@imperialviolet.org http://www.imperialviolet.org


------------------------------

Message: 15
Date: Thu, 25 Sep 2008 13:46:36 +0200
From: Maarten Hazewinkel <maarten.hazewinkel@gmail.com>
Subject: Re: [Haskell-cafe] Google Android
To: Adam Langley <agl@imperialviolet.org>
Cc: "Galchin, Vasili" <vigalchin@gmail.com>,
    "haskell-cafe@haskell.org" <haskell-cafe@haskell.org>
Message-ID: <3E3F4C9A-18F7-4C39-8701-839107B490CD@mac.com>
Content-Type: text/plain; charset=US-ASCII; format=flowed

On 25 Sep 2008, at 13:33, Adam Langley wrote:

> A Google
> search for "haskell java" turns up at least one good candidate[1], but
> if you manage to get that working well, binding the APIs is a rather
> trivial task ;)
>
> [1] http://www.cse.unsw.edu.au/~pls/thesis-topics/ghcjava.html

That's actually just a thesis proposal, not actual work done.
Try this for something closer to realization:

http://www.cs.rit.edu/~bja8464/lambdavm/


Regards,

Maarten


------------------------------

Message: 16
Date: Thu, 25 Sep 2008 15:39:22 +0200
From: "minh thu" <noteed@gmail.com>
Subject: [Haskell-cafe] Where is OpenGL loadMatrix ?
To: "Haskell-cafe Cafe" <haskell-cafe@haskell.org>
Message-ID:
    <40a414c20809250639s2da31e6fv24c797ca3e328381@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1

Hi,

I can't find the loadMatrix function in
http://hackage.haskell.org/packages/archive/OpenGL/latest/doc/html/Graphics-Rendering-OpenGL-GL-CoordTrans.html

Should I use loadIdentity then multMatrix instead ?

Thank you,
Thu


------------------------------

Message: 17
Date: Thu, 25 Sep 2008 15:45:21 +0200
From: " Krzysztof Skrz?tnicki " <gtener@gmail.com>
Subject: Re: [Haskell-cafe] Where is OpenGL loadMatrix ?
To: "minh thu" <noteed@gmail.com>
Cc: Haskell-cafe Cafe <haskell-cafe@haskell.org>
Message-ID:
    <220e47b40809250645o51a3ab47mbde6e0b7c90e28e0@mail.gmail.com>
Content-Type: text/plain; charset=UTF-8

On Thu, Sep 25, 2008 at 15:39, minh thu <noteed@gmail.com> wrote:
>
> Hi,
>
> I can't find the loadMatrix function in
> http://hackage.haskell.org/packages/archive/OpenGL/latest/doc/html/Graphics-Rendering-OpenGL-GL-CoordTrans.html
>
> Should I use loadIdentity then multMatrix instead ?
>
> Thank you,
> Thu
> _______________________________________________
> Haskell-Cafe mailing list
> Haskell-Cafe@haskell.org
> http://www.haskell.org/mailman/listinfo/haskell-cafe

>From what I can see in the source, loadMatrix is method of class
MatrixComponent [1]:

instance MatrixComponent GLfloat_ where
  getMatrix = getFloatv
  loadMatrix = glLoadMatrixf
  loadTransposeMatrix = glLoadTransposeMatrixfARB
  multMatrix_ = glMultMatrixf
  multTransposeMatrix = glMultTransposeMatrixfARB
  rotate a (Vector3 x y z) = glRotatef a x y z
  translate (Vector3 x y z) = glTranslatef x y z
  scale = glScalef

However, for some reason it is not exported:

  MatrixOrder(..), MatrixComponent(rotate,translate,scale), Matrix(..),

Best regards

Christopher Skrzętnicki

[1]: http://hackage.haskell.org/packages/archive/OpenGL/latest/doc/html/src/Graphics-Rendering-OpenGL-GL-CoordTrans.html#MatrixComponent

------------------------------

Message: 18
Date: Thu, 25 Sep 2008 15:59:35 +0200
From: Achim Schneider <barsoap@web.de>
Subject: [Haskell-cafe] Re: Where is OpenGL loadMatrix ?
To: haskell-cafe@haskell.org
Message-ID: <20080925155935.7ea6f1cc@solaris>
Content-Type: text/plain; charset=US-ASCII

"minh thu" <noteed@gmail.com> wrote:

> I can't find the loadMatrix function in
> http://hackage.haskell.org/packages/archive/OpenGL/latest/doc/html/Graphics-Rendering-OpenGL-GL-CoordTrans.html
>
> Should I use loadIdentity then multMatrix instead ?
>
You're supposed to use withMatrix and regard OpenGL not as an
imperative language, but as a markup language coincidentally using
"do" to specify (flattened) lists. I even read about some library
managing display lists transparently for you, but I can't recall where.

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for copyright history. All rights reserved. Copying, hiring, renting,
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------------------------------

Message: 19
Date: Thu, 25 Sep 2008 16:12:31 +0200
From: "minh thu" <noteed@gmail.com>
Subject: Re: [Haskell-cafe] Re: Where is OpenGL loadMatrix ?
To: "Achim Schneider" <barsoap@web.de>
Cc: haskell-cafe@haskell.org
Message-ID:
    <40a414c20809250712m2d4f9effy35506a0934dfeaf7@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1

2008/9/25 Achim Schneider <barsoap@web.de>:
> "minh thu" <noteed@gmail.com> wrote:
>
>> I can't find the loadMatrix function in
>> http://hackage.haskell.org/packages/archive/OpenGL/latest/doc/html/Graphics-Rendering-OpenGL-GL-CoordTrans.html
>>
>> Should I use loadIdentity then multMatrix instead ?
>>
> You're supposed to use withMatrix and regard OpenGL not as an
> imperative language, but as a markup language coincidentally using
> "do" to specify (flattened) lists. I even read about some library
> managing display lists transparently for you, but I can't recall where.

If you're right, it's weird there are things like  loadIdentity, $=,
... and it is
even weirder to not provide loadMatrix (which can be done with
loadIdenity and multMatrix).

Anyway, the bindings are not that much functionnal, even with things
like withMatrix.

Cheers
Thu


------------------------------

Message: 20
Date: Thu, 25 Sep 2008 10:18:13 -0400
From: "Anthony LODI" <anthony.lodi@gmail.com>
Subject: [Haskell-cafe] StateWriter: a monad-writing exercise
To: haskell-cafe@haskell.org
Message-ID:
    <d58ec4e0809250718xfb315aevc567750d7f5c99dc@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1

Hello haskell-cafe,

In my application I have a complex state threaded through long
computation chains, and I need a way to log all state changes (so that
the evolving state can be animated/replayed somewhere else).
Initially I tried combining State and Writer monads but this allows
for the possibility to change the state, and forget to write a log
entry, etc.

So I decided to write a separate monad, StateWriter l s, that takes a
state-modifying function, l->s->s (l is an ADT for all the allowable
state transitions), an initial state s, and only allows s to change by
appending 'l' log entries inside the monad.  The net result is that I
should have read-only access to the current state inside the monad,
and all state transitions should be logged (by going through the one
function, the log entries serve as witnesses to all state
transitions).

Anyway, here's my (very rough!) first stab at the problem.  This is
the first time I've tried writing a monad so any comments/critiques
are much appreciated.

Also, about the 'StateWriter' idea in general: am I just (poorly?)
reimplementing something obvious?  Is it unlikely to scale well on
real-world problems?  Is there some way to combine the existing State
and Writer monads to avoid having to do this?

If there's nothing seriously wrong here, I was thinking my next step
would be to try changing the lists to monoids (like in the Writer
monad), and then to try writing a transformer version of the whole
thing.

Cheers,

- Anthony LODI


================================================================================

{-# LANGUAGE MultiParamTypeClasses,
            FunctionalDependencies,
            FlexibleInstances #-}

newtype StateWriter l s a = StateWriter { _runSWriter :: (l -> s -> s)
                                                    -> [l]
                                                    -> s
                                                    -> (a, [l], s)
                                      }


instance Monad (StateWriter l s) where
  return a = StateWriter $ \_ ls s -> (a, ls, s)

  (StateWriter x) >>= f = StateWriter $ \fn ls s ->
                                let (v, ls', s') = x fn ls s
                                in
                                  _runSWriter (f v) fn ls' s'

class MonadStateWriter m l s | m -> l s where
put :: l -> m ()
get :: m s

instance MonadStateWriter (StateWriter l s) l s where
put l = StateWriter $ \fn ls s -> ((), ls ++ [l], fn l s)
get = StateWriter $ \fn ls s -> (s, ls, s)


runSWriter :: StateWriter l s a -> (l -> s -> s) -> s -> (a, [l], s)
runSWriter sw fn = _runSWriter sw fn []


--------------------------------------------------------------------------------


data Ops = Inc
        | Dec
          deriving (Show)

test :: StateWriter Ops Int String
test = do
put Inc
put Inc
put Inc
val <- get
let op = if val == 3 then Dec else Inc
put op
return "done"

stateFn :: Ops -> Int -> Int
stateFn Inc s = s + 1
stateFn Dec s = s - 1

runtest = runSWriter test stateFn 0 -- ("done",[Inc,Inc,Inc,Dec],2)


------------------------------

Message: 21
Date: Thu, 25 Sep 2008 16:34:18 +0200 (CEST)
From: Henning Thielemann <lemming@henning-thielemann.de>
Subject: Re: [Haskell-cafe] StateWriter: a monad-writing exercise
To: Anthony LODI <anthony.lodi@gmail.com>
Cc: haskell-cafe@haskell.org
Message-ID: <Pine.SOC.4.64.0809251631320.21141@verdi>
Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed


On Thu, 25 Sep 2008, Anthony LODI wrote:

> Hello haskell-cafe,
>
> In my application I have a complex state threaded through long
> computation chains, and I need a way to log all state changes (so that
> the evolving state can be animated/replayed somewhere else).
> Initially I tried combining State and Writer monads but this allows
> for the possibility to change the state, and forget to write a log
> entry, etc.

Instead of rewriting from scratch, you can also define

  newtype StateWriter l s a = StateWriter (StateT s (Writer l) a)

and then the monad instance is just about wrapping and unwrapping. Or you
use {-# LANGUAGE GeneralizedNewtypeDeriving #-} and 'deriving Monad'.


------------------------------

Message: 22
Date: Thu, 25 Sep 2008 17:39:26 +0300
From: "Bit Connor" <bit@mutantlemon.com>
Subject: Re: [Haskell-cafe] Re: Where is OpenGL loadMatrix ?
To: "minh thu" <noteed@gmail.com>
Cc: Achim Schneider <barsoap@web.de>, haskell-cafe@haskell.org
Message-ID:
    <6205bd290809250739u4b987f7cm285624fb9d5b6601@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1

withMatrix doesn't seem to have anything to do with glLoadMatrix.

You are right that you can do glLoadMatrix with loadIdentity and multMatrix.

To directly load a matrix, use the function "matrix" (with a Nothing
argument). This will internally call the loadMatrix function that
Krzysztof mentioned (which is correctly not exported).

Note that in addition to loading a matrix, the "matrix" function is
also used for retrieving the current matrix. (glGetFloatv with
argument GL_MODELVIEW_MATRIX and friends).

On Thu, Sep 25, 2008 at 5:12 PM, minh thu <noteed@gmail.com> wrote:
> 2008/9/25 Achim Schneider <barsoap@web.de>:
>> "minh thu" <noteed@gmail.com> wrote:
>>
>>> I can't find the loadMatrix function in
>>> http://hackage.haskell.org/packages/archive/OpenGL/latest/doc/html/Graphics-Rendering-OpenGL-GL-CoordTrans.html
>>>
>>> Should I use loadIdentity then multMatrix instead ?
>>>
>> You're supposed to use withMatrix and regard OpenGL not as an
>> imperative language, but as a markup language coincidentally using
>> "do" to specify (flattened) lists. I even read about some library
>> managing display lists transparently for you, but I can't recall where.
>
> If you're right, it's weird there are things like  loadIdentity, $=,
> ... and it is
> even weirder to not provide loadMatrix (which can be done with
> loadIdenity and multMatrix).
>
> Anyway, the bindings are not that much functionnal, even with things
> like withMatrix.
>
> Cheers
> Thu
> _______________________________________________
> Haskell-Cafe mailing list
> Haskell-Cafe@haskell.org
> http://www.haskell.org/mailman/listinfo/haskell-cafe
>


------------------------------

Message: 23
Date: Thu, 25 Sep 2008 16:48:25 +0200
From: "minh thu" <noteed@gmail.com>
Subject: Re: [Haskell-cafe] Re: Where is OpenGL loadMatrix ?
To: "Bit Connor" <bit@mutantlemon.com>
Cc: Achim Schneider <barsoap@web.de>, haskell-cafe@haskell.org
Message-ID:
    <40a414c20809250748i2ffebafal5d20edcf7dff2bfc@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1

2008/9/25 Bit Connor <bit@mutantlemon.com>:
> withMatrix doesn't seem to have anything to do with glLoadMatrix.
>
> You are right that you can do glLoadMatrix with loadIdentity and multMatrix.
>
> To directly load a matrix, use the function "matrix" (with a Nothing
> argument). This will internally call the loadMatrix function that
> Krzysztof mentioned (which is correctly not exported).
>
> Note that in addition to loading a matrix, the "matrix" function is
> also used for retrieving the current matrix. (glGetFloatv with
> argument GL_MODELVIEW_MATRIX and friends).

Ok, thank you,
Thu


------------------------------

Message: 24
Date: Thu, 25 Sep 2008 16:52:52 +0200
From: Achim Schneider <barsoap@web.de>
Subject: [Haskell-cafe] Re: Where is OpenGL loadMatrix ?
To: haskell-cafe@haskell.org
Message-ID: <20080925165252.5d88839b@solaris>
Content-Type: text/plain; charset=US-ASCII

"minh thu" <noteed@gmail.com> wrote:

> Anyway, the bindings are not that much functionnal, even with things
> like withMatrix.
>
http://thread.gmane.org/gmane.comp.lang.haskell.cafe/35444/focus=35713

Mind you: regarding 3d, I barely manage to code up camera movements.
That is, I don't use it much at all.

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for copyright history. All rights reserved. Copying, hiring, renting,
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------------------------------

Message: 25
Date: Thu, 25 Sep 2008 18:09:18 +0200
From: Manlio Perillo <manlio_perillo@libero.it>
Subject: Re: [Haskell-cafe] pure Haskell database
To: Rich Neswold <rich.neswold@gmail.com>
Cc: Haskell Cafe mailing list <haskell-cafe@haskell.org>
Message-ID: <48DBB7AE.9010002@libero.it>
Content-Type: text/plain; charset=UTF-8; format=flowed

Rich Neswold ha scritto:
> On Wed, Sep 24, 2008 at 4:17 PM, Manlio Perillo
> <manlio_perillo@libero.it <mailto:manlio_perillo@libero.it>> wrote:
>
>    I need a simple, concurrent safe, database, written in Haskell.
>    A database with the interface of Data.Map would be great, since what
>    I need to to is atomically increment some integer values, and I
>    would like to avoid to use SQLite.
>
>
> How about  "MVar (Map k Int)"?  or even "Map k (MVar Int)"?
>

Yes, it is a solution; and I can run a thread that every N seconds
writes the database to a file.

But this works only if the database is used by only one process.


Manlio Perillo


------------------------------

Message: 26
Date: Thu, 25 Sep 2008 12:14:55 -0400
From: "Lihn, Steve" <horng_twu_lihn@merck.com>
Subject: [Haskell-cafe] Microsoft's Craig Mundie outlines the future
    of    computing
To: <haskell-cafe@haskell.org>
Message-ID:
    <6BD267D89E66B9499514F119920E583C029A2E90@usctmx1110.merck.com>
Content-Type: text/plain; charset="us-ascii"


http://news.cnet.com/8301-13953_3-10050826-80.html?part=rss&subj=news&ta
g=2547-1_3-0-5

"We have to see a paradigm change in the way we write applications." He
also said that software development hasn't graduated to become a formal
engineering discipline. "The resilience of systems is not up to the
task," he said. "We have to master the transition to a parallel
programming environment, with highly distributed, concurrent systems.
It's nascent at this point but it's required to achieve these
capabilities."

Sounds like Haskell will fit well in this future world.

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------------------------------

Message: 27
Date: Thu, 25 Sep 2008 18:27:19 +0200
From: "Svein Ove Aas" <svein.ove@aas.no>
Subject: [Haskell-cafe] GHC 6.10, OS X, Fink and CPPFLAGS
To: "Haskell Cafe" <haskell-cafe@haskell.org>
Message-ID:
    <221b53ab0809250927l2caa3359pe699c7ff6c52a8d1@mail.gmail.com>
Content-Type: text/plain; charset=UTF-8

While trying to test 6.10, I ran into the issue that a number of the
libraries it wants are not installed by default, and are most
conveniently added via Fink. This includes gmp, binutils, readline,
etc.

/sw/ is not in the default gcc path, of course, so the usual solution
is to add -I/sw/include, -L/sw/lib, etc. to it via the CPPFLAGS and
LDFLAGS environment variables, which are supported by most[1]
autoconf-based packages. The help text for ghc's configure script does
in fact suggest that this is the case, and it has some code meant to
read it; broken code, as it happens.

As it is, the script fails to propagate those variables to whatever is
responsible for compiling the RTS, which fails with a missing gmp.h,
bfd.h, and so on. All those files exist live quite happily in
/sw/include, and would no doubt appreciate visiting makefiles.

So my question is two-fold:
Is the help file wrong? Is there some other way to do it?
Or is this in fact a bug, and if so, will any of you volunteer to fix
it for me? ^_^


------------------------------

Message: 28
Date: Thu, 25 Sep 2008 18:57:05 +0200
From: Ketil Malde <ketil@malde.org>
Subject: Re: [Haskell-cafe] Climbing up the shootout...
To: "John Van Enk" <vanenkj@gmail.com>
Cc: Bulat Ziganshin <Bulat.Ziganshin@gmail.com>,
    haskell-cafe@haskell.org
Message-ID: <87skro88pq.fsf@malde.org>
Content-Type: text/plain; charset=us-ascii

"John Van Enk" <vanenkj@gmail.com> writes:

> I'm going to have to agree with David... even if you ignore the multi-threaded
> projects, why couldn't the C programs just implement very specific version of
> the third party library inside their code?

Or they could just FFI to the Haskell libraries :-)

-k
--
If I haven't seen further, it is by standing in the footprints of giants


------------------------------

Message: 29
Date: Thu, 25 Sep 2008 18:15:56 +0100
From: Eric <eeoam@ukfsn.org>
Subject: [Haskell-cafe] Problem with existential quantification
To: Haskell-cafe <haskell-cafe@haskell.org>
Message-ID: <48DBC74C.3030303@ukfsn.org>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Dear all,

I've written a function with the following type:

build :: Bifunctor s => (forall b. (s a b  ->  b) -> b)  ->  Fix s a

When I try to compile I get the following error:

Illegal polymorphic or qualified type: forall b. (s a b -> b) -> b
In the type signature for `build':
  build :: (Bifunctor s) => (forall b. (s a b -> b) -> b) -> Fix s a

What's happening?

E.M.



------------------------------

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