Re: [Haskell-cafe] ghc 6.8.2 issue

[Galchin, Vasili]

Duncan,

 By installing localling, I "runhaskell Setup.hs configure
--prefix=$HOME" plus add local path to LD_LIBRARY_PATH and LD_RUN_PATH? On
Linux, does ghc use .so's or is it linked statically?

Vasili

On Mon, Jun 2, 2008 at 5:38 AM, Duncan Coutts <[EMAIL PROTECTED]>
wrote:

>
> On Mon, 2008-06-02 at 00:07 -0500, Galchin, Vasili wrote:
> > Hello,
> >
> >   I have been developing new code for the "unix" package. I have
> > run into what I think are ghc 6.8.2 anomalies but couldn't see a
> > pattern. Possibly now I do. I have been using the 32-bit x86 ghc
> > binary that I downloaded from http://www.haskell.org and running on
> > Ubuntu Linux. I am pretty I can repeat now. Everything is ok until I
> > do "sudo runhaskell Setup.hs install" which installs a new "unix"
> > package that I just built. Of course the "intall" installs
> > into /usr/local/lib/unix-2.3.0.0/ghc-6.8.2. The "install" seems to
> > destroy some ghc compiler state under /usr/local ...
>
> That sounds right. You're replacing the unix-2.3.0.0 library that comes
> with ghc-6.8.2 with your own version. It is highly unlikely to be ABI
> compatible with the one you are replacing and so all the other packages
> that already depends on the existing unix-2.3.0.0 library end up broken.
> You'd expect this kind of breakage to be exposed as link errors and
> segfaults.
>
> I suggest you do not replace any of the libraries that come with ghc. To
> be more precise, it is perfectly ok to *add new versions* but it is not
> ok to *replace existing versions* without rebuilding all the other libs
> that depend on it.
>
> Make sense?
>
> So if you really want to make changes to the unix lib, make sure you
> change the version number too. I also suggest not installing the
> packages as root, just install them locally. That way you can guarantee
> you never mess up your ghc install. You would be able to revert to a
> clean ghc install just by removing your
> ~/.ghc/$arch/ghc-6.8.2/package.conf file which will unregister *all*
> locally registered packages. To unregister individual packages use
> ghc-pkg --user unregister $pkgname
>
> Duncan
>
>
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Re: [Haskell-cafe] Mutually Recursive Modules

[ajb]

G'day all.

Quoting Isaac Dupree <[EMAIL PROTECTED]>:


Luckily,
it is very often the case that your code will be better off anyway if
refactored to have less module recursion. (though not always.)


Nonetheless, I prefer not to leave the robustness of my code to luck.
Besides, if I liked structuring code around artificial language
restrictions, I'd be programming in C, not Haskell.

Cheers,
Andrew Bromage
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Re: [Haskell-cafe] ghc 6.8.2 issue

[Galchin, Vasili]

Hi Duncan,

 Not sure I agree the behavior is ok. E.g. here is a build of mmap:

[EMAIL PROTECTED]:~/FTP/Haskell/bytestring-mmap-0.2.0$ runhaskell Setup.lhs
clean
cleaning...
[EMAIL PROTECTED]:~/FTP/Haskell/bytestring-mmap-0.2.0$ runhaskell Setup.lhs
configure
Configuring bytestring-mmap-0.2.0...
[EMAIL PROTECTED]:~/FTP/Haskell/bytestring-mmap-0.2.0$ runhaskell Setup.lhs
build
Preprocessing library bytestring-mmap-0.2.0...
Building bytestring-mmap-0.2.0...
[1 of 3] Compiling System.IO.Posix.MMap.Internal (
System/IO/Posix/MMap/Internal.hs, dist/build/System/IO/Posix/MMap/Internal.o
)
[2 of 3] Compiling System.IO.Posix.MMap.Lazy ( System/IO/Posix/MMap/Lazy.hs,
dist/build/System/IO/Posix/MMap/Lazy.o )
[3 of 3] Compiling System.IO.Posix.MMap ( System/IO/Posix/MMap.hs,
dist/build/System/IO/Posix/MMap.o )
/usr/bin/ar: creating dist/build/libHSbytestring-mmap-0.2.0.a

at this point rebuild and install the "unix" package ...

[EMAIL PROTECTED]:~/FTP/Haskell/bytestring-mmap-0.2.0$ runhaskell Setup.lhs
clean
cleaning...
[EMAIL PROTECTED]:~/FTP/Haskell/bytestring-mmap-0.2.0$ runhaskell Setup.lhs
configure
Configuring bytestring-mmap-0.2.0...
[EMAIL PROTECTED]:~/FTP/Haskell/bytestring-mmap-0.2.0$ runhaskell Setup.lhs
build
Setup.lhs: error reading dist/setup-config; run "setup configure" command?

"dist/setup-config" is not being populated at the end. In your response
below, are you saying that teh segfaults occur because ghc itself relies on
the "unix" package?

Thanks, Vasili




On Mon, Jun 2, 2008 at 5:38 AM, Duncan Coutts <[EMAIL PROTECTED]>
wrote:

>
> On Mon, 2008-06-02 at 00:07 -0500, Galchin, Vasili wrote:
> > Hello,
> >
> >   I have been developing new code for the "unix" package. I have
> > run into what I think are ghc 6.8.2 anomalies but couldn't see a
> > pattern. Possibly now I do. I have been using the 32-bit x86 ghc
> > binary that I downloaded from http://www.haskell.org and running on
> > Ubuntu Linux. I am pretty I can repeat now. Everything is ok until I
> > do "sudo runhaskell Setup.hs install" which installs a new "unix"
> > package that I just built. Of course the "intall" installs
> > into /usr/local/lib/unix-2.3.0.0/ghc-6.8.2. The "install" seems to
> > destroy some ghc compiler state under /usr/local ...
>
> That sounds right. You're replacing the unix-2.3.0.0 library that comes
> with ghc-6.8.2 with your own version. It is highly unlikely to be ABI
> compatible with the one you are replacing and so all the other packages
> that already depends on the existing unix-2.3.0.0 library end up broken.
> You'd expect this kind of breakage to be exposed as link errors and
> segfaults.
>
> I suggest you do not replace any of the libraries that come with ghc. To
> be more precise, it is perfectly ok to *add new versions* but it is not
> ok to *replace existing versions* without rebuilding all the other libs
> that depend on it.
>
> Make sense?
>
> So if you really want to make changes to the unix lib, make sure you
> change the version number too. I also suggest not installing the
> packages as root, just install them locally. That way you can guarantee
> you never mess up your ghc install. You would be able to revert to a
> clean ghc install just by removing your
> ~/.ghc/$arch/ghc-6.8.2/package.conf file which will unregister *all*
> locally registered packages. To unregister individual packages use
> ghc-pkg --user unregister $pkgname
>
> Duncan
>
>
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Re: [Haskell-cafe] [Newbie question] -- Looping stdin until condition is met

[Neil Mitchell]

Hi

> The best thing to do is bypass read and use 'reads' to define your
> own safe read.
>
>maybeRead :: Read a => String -> Maybe a
>maybeRead s = case reads s of
>[(x, "")] -> Just x
>_ -> Nothing

Or just use the Safe package:
http://hackage.haskell.org/cgi-bin/hackage-scripts/package/safe

http://hackage.haskell.org/packages/archive/safe/0.2/doc/html/Safe.html#v%3AreadMay

Thanks

Neil
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Re: [Haskell-cafe] [Newbie question] -- Looping stdin until condition is met

[Ryan Ingram]

On 5/30/08, Martin Blais <[EMAIL PROTECTED]> wrote:
> Dear Philip, could you point your virtual finger towards a
> reference/paper/book/any-bleeping-thing that would help this simple
> beginner understand why it doesn't work in this case? I'm trying to
> picture why a "read" function that terminates the program would be
> useful anywhere. In fact, any library function other than something like
> UNIX's "exit" or "kill" which terminates my program is not really
> welcome in any of my computer programs, but then again, I haven't yet
> been illuminated by the genie of pure functional languages.  A reference
> would be awesome.

As others have pointed out, the reason why it doesn't work is due to
lazy evaluation; the exception is "hidden" in a pure value and isn't
triggered until some other bit of code causes the pure value to be
evaluated.  You can force the exception to be generated in your catch
block by using "seq" (or "$!", which is implemented using "seq").
This forces the evaluation to happen at that point, although there are
a lot of gotchas involved; for Int it works fine, though.

Your question, then, requires asking "why would you want to hide an
exception in a pure value"?  The answer to that is quite interesting,
but here's a simpler example that might enlighten you:

head :: [a] -> a
head (x:_) = x
head _ = error "head: empty list"

Just as you are required to prove before calling "head" that you
aren't passing an empty list, for your program to be total, you should
prove before calling "read" that the string parses properly.  If you
can't provide that proof (because, in this case, the string is
provided by the user), you should be using another function for
parsing.

Don suggested "reads" to implement "maybeRead", which seems like a
great idea to me.

  -- ryan
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Re: [Haskell-cafe] Implementing ParseChart with Data.Map

[Neil Mitchell]

Hi

> case insertLookupWithKey (\_ -> Set.union) k (Set.singleton v) chart of
>  (Nothing, chart) -> Just chart
>  (Just set, chart) | Set.member v set -> Nothing
>  | otherwise -> Just chart
>
> but notice that the set is still traversed twice.

Yes, I missed that bit. I don't see any way of reducing that, other
than using an unsafePerformIO and IORef to track the combining
function - which is probably a really bad idea.

Thanks

Neil
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Re: [Haskell-cafe] Implementing ParseChart with Data.Map

[Krasimir Angelov]

Not completely! This is a possible implementation:

case insertLookupWithKey (\_ -> Set.union) k (Set.singleton v) chart of
  (Nothing, chart) -> Just chart
  (Just set, chart) | Set.member v set -> Nothing
  | otherwise -> Just chart

but notice that the set is still traversed twice.

On Tue, Jun 3, 2008 at 12:07 AM, Neil Mitchell <[EMAIL PROTECTED]> wrote:
> Hi Krasimir,
>
>> insert :: k -> v -> Chart k v -> Maybe (Chart k v)
>>
>> where the result is (Just _) if the (k,v) is actually added to the
>> chart or Nothing if it was already there and nothing have to be done.
>
> insertLookupWithKey :: Ord k => (k -> a -> a -> a) -> k -> a -> Map k
> a -> (Maybe a, Map k a)
>
> This should provide the information you need, without the double
> traversal of the data structure.
>
> Thanks
>
> Neil
>
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Re: [Haskell-cafe] cabal install fail for happs-hsp-template

[Duncan Coutts]

On Mon, 2008-06-02 at 09:42 -0700, Thomas Hartman wrote:
> Can cabal install be made to work for this package?
> *
> [EMAIL PROTECTED]:~>sudo cabal install happs-hsp-template
> [sudo] password for thartman:
> cabal: internal error: could not construct a valid install plan.
> The proposed (invalid) plan contained the following problems:
> Package Cabal is required by several packages, but they require
> inconsistent versions:
>   package ghc-6.8.2 requires Cabal-1.2.3.0
>   package plugins-1.2 requires Cabal-1.5.2

The package deps are not actually inconsistent, the problem is that the
current cabal-install dependency resolution algorithm is completely
naive and comes up with an invalid install plan.

I'll let people know when the new dep resolver for cabal-install is
ready (hopefully just a few days now). It should address this issue.

Duncan

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Re: [Haskell-cafe] Implementing ParseChart with Data.Map

[Duncan Coutts]

On Mon, 2008-06-02 at 22:35 +0200, Krasimir Angelov wrote:

> The problem with this is that both the Map and the Set are traversed
> twice. The first time from lookup/member and the second time from
> insert. Does someone have an idea how to do this with the current
> libraries?


> The chart manipulation is in the tight loop of my application so I
> need fast code. Any other ideas?

I'm not sure if it helps your application but we had a discussion on
#haskell the other day about Data.Map and were talking about a general
insert/modify/delete operator like:

modify :: k -> Map k e -> (e, Maybe e -> Map k e)

so it's a lookup that returns the element at k and also a continuation
that lets you rebuild a new map with an altered element. I guess that
doesn't account for the element not existing. There's probably a
generalisation that does.

Duncan

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Re: [Haskell-cafe] hs-plugins compile error

[Thomas Hartman]

after darcs record,

 darcs send -o file.patch

and then send file.patch via email to the maintainer.

2008/6/2 Edsko de Vries <[EMAIL PROTECTED]>:
> Hi Don,
>
> Is this the kind of thing you mean (I'm not really a darcs user; this is
> the patch created by darcs record):
>
> [Hide some names to remove ambiguity errors
> Edsko de Vries <[EMAIL PROTECTED]>**20080602202001] {
> hunk ./src/System/Plugins/Env.hs 76
> -import Distribution.Package
> +import Distribution.Package hiding (packageName)
> hunk ./src/System/Plugins/PackageAPI.hs 43
> -import Distribution.Package
> +import Distribution.Package hiding (depends, packageName)
> hunk ./src/System/Plugins/ParsePkgConfCabal.hs 9
> -import Distribution.Package
> +import Distribution.Package hiding (depends)
> }
>
> Edsko
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Re: [Haskell-cafe] Implementing ParseChart with Data.Map

[Neil Mitchell]

Hi Krasimir,

> insert :: k -> v -> Chart k v -> Maybe (Chart k v)
>
> where the result is (Just _) if the (k,v) is actually added to the
> chart or Nothing if it was already there and nothing have to be done.

insertLookupWithKey :: Ord k => (k -> a -> a -> a) -> k -> a -> Map k
a -> (Maybe a, Map k a)

This should provide the information you need, without the double
traversal of the data structure.

Thanks

Neil
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Re: [Haskell-cafe] Vancouver Haskell users meeting

[Don Stewart]

jstrait:
> Anyone else here from Vancouver (Canada)?  I thought it would be great 
> to have a little informal get-together at a local cafe and share how 
> we're currently using Haskell, or really anything (problems,  
> comparisons, useful software tools, etc.) in relation to Haskell.
> 
> I'm scheduling a meeting for this Thursday, June 5th. for 7PM at 
>  Waazubee Cafe - 
> http://www.waazubee.com/content/directions.php  (at Commercial Dr. and 
> 1st Ave.) 
> 
> They have wireless internet access.  I'll get a table near the back, 
> bring my laptop, and will have a copy of Hudak's SOE book (the front 
> cover is impossible to miss) out on the table.
> 
> If anyone wants to meet, but this Thursday is not a good day for you, 
> let me know what days are better and we'll move the meeting.  If anyone 
> is sure that they will come this Thursday, you might let me know, so I 
> can have an idea about the resistance in changing the day, if needed.

Great! I've added these details to the events listing on http://haskell.org
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[Haskell-cafe] Vancouver Haskell users meeting

[Jon Strait]

Anyone else here from Vancouver (Canada)?  I thought it would be great 
to have a little informal get-together at a local cafe and share how 
we're currently using Haskell, or really anything (problems,  
comparisons, useful software tools, etc.) in relation to Haskell.


I'm scheduling a meeting for this Thursday, June 5th. for 7PM at 
 Waazubee Cafe - 
http://www.waazubee.com/content/directions.php  (at Commercial Dr. and 
1st Ave.) 

They have wireless internet access.  I'll get a table near the back, 
bring my laptop, and will have a copy of Hudak's SOE book (the front 
cover is impossible to miss) out on the table.


If anyone wants to meet, but this Thursday is not a good day for you, 
let me know what days are better and we'll move the meeting.  If anyone 
is sure that they will come this Thursday, you might let me know, so I 
can have an idea about the resistance in changing the day, if needed.


Thanks,

Jon
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[Haskell-cafe] Implementing ParseChart with Data.Map

[Krasimir Angelov]

Hi,

I have to write ParseChart implementation with Data.Map/Set. The chart
is type like this:

type Chart k v = Map k (Set v)

now I need operation like:

insert :: k -> v -> Chart k v -> Maybe (Chart k v)

where the result is (Just _) if the (k,v) is actually added to the
chart or Nothing if it was already there and nothing have to be done.
The straight forward implementation is:

case Map.lookup k chart of
  Nothing -> Just (Map.insert k (Set.singleton v) chart)
  Just set | Set.member v set -> Nothing
   | otherwise-> Just (Map.insert k
(Set.insert v set) chart)

The problem with this is that both the Map and the Set are traversed
twice. The first time from lookup/member and the second time from
insert. Does someone have an idea how to do this with the current
libraries?

There are the Map.updateLookupWithKey and the Map.alter functions:

updateLookupWithKey :: Ord k => (k -> a -> Maybe a) -> k -> Map k a ->
(Maybe a,Map k a)
alter :: Ord k => (Maybe a -> Maybe a) -> k -> Map k a -> Map k a

which are the closest that I need. The problem is that the first
doesn't allow the client function to be called if there isn't matching
key in the map and the second is doesn't allow to return value from
the client function. What I really need is an alterLookúp function:

alterLookúp :: Ord k => (Maybe a -> (b,Maybe a)) -> k -> Map k a -> (b,Map k a)

The chart manipulation is in the tight loop of my application so I
need fast code. Any other ideas?

Regards,
   Krasimir
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[Haskell-cafe] Vancouver Haskell users meeting

[Jon Strait]

Anyone else here from Vancouver (Canada)?  I thought it would be great
to have a little informal get-together at a local cafe and share how
we're currently using Haskell, or really anything (problems, 
comparisons, useful software tools, etc.) in relation to Haskell. 

I'm scheduling a meeting for this Thursday, June 5th. for 7PM at Waazubee Cafe. 
(At Commercial Dr. and 1st Ave.)  

They have wireless internet access.  I'll get a table near the back,
bring my laptop, and will have a copy of Hudak's SOE book (the front
cover is impossible to miss) out on the table. 

If anyone wants to meet, but this Thursday is not a good day for you,
let me know what days are better and we'll move the meeting.  If anyone
is sure that they will come this Thursday, you might let me know, so I
can have an idea about the resistance in changing the day, if needed.

Thanks,

Jon



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Re: [Haskell-cafe] Re: [ANN] bloomfilter 1.0 - Fast immutable and mutable Bloom filters

[Edward Kmett]

On Sat, May 31, 2008 at 6:22 PM, Jim Snow <[EMAIL PROTECTED]> wrote:
> In practice, one might use something like 32 hash tables.  This yields a
> false positive rate of 1/(2^32).  Their most obvious application is to store
> the dictionary for a spell checker in a space-efficient way, though I have a
> friend who wrote a paper on using them for router caches.

One minor technicality is that you don't actually use k separate hash
tables. You use k separate hash functions, and hash using different
functions into the same physical table with a goal of having
approximately half of
the bits in the table set when all of your data is hashed.
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Re: [Haskell-cafe] hs-plugins compile error

[Edsko de Vries]

Hi Don,

Is this the kind of thing you mean (I'm not really a darcs user; this is
the patch created by darcs record):

[Hide some names to remove ambiguity errors
Edsko de Vries <[EMAIL PROTECTED]>**20080602202001] {
hunk ./src/System/Plugins/Env.hs 76
-import Distribution.Package
+import Distribution.Package hiding (packageName)
hunk ./src/System/Plugins/PackageAPI.hs 43
-import Distribution.Package
+import Distribution.Package hiding (depends, packageName)
hunk ./src/System/Plugins/ParsePkgConfCabal.hs 9
-import Distribution.Package
+import Distribution.Package hiding (depends)
}

Edsko
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Re: [Haskell-cafe] What is the maturity of Haskell Web Frameworks

[Keith Fahlgren]

On 6/2/08 10:21 AM, Don Stewart wrote:

aditya_siram:

I am building a web-app that, in broad strokes, allows a leader to
assign tasks to team members and allows team members to
accept/reject/pick tasks that they want to do. 


I really like Haskell and I would like to use it to implement the
solution. Are frameworks like Happs ready? Not so much in terms of
documentation, but in functionality and stability. 


HAppS is nice (see hpaste.org for example, which is nice and simple, and
has been running for over a year).

Another nice option in Haskell is using something like HStringTemplate
or the xhtml combinators  with fastcgi hooked into GHC's concurrency
mechanisms.


If you're interested in the background of rolling your own web stuff, I like 
Paul Brown's description of building perpubplat here: http://mult.ifario.us/t/blog



HTH,
Keith

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[Haskell-cafe] Re: modelling C in Haskell ..

[Ben Franksen]

Galchin, Vasili wrote:
>
> typedef struct blah
> {
>int val1;
> 
>union {
> 
>int  val2;
> 
>struct {
> 
>  int val3;
> 
>  int val4;
>}
>}
> }C_type;
> 
> question: in Haskell, can I embed definition of the "union" inside of the
> C typedef, i.e. recursion definition? Or must I have a separate definition
> for the "union" which I "instantiate" inside the Haskell "typedef", i.e.
> Haskell "data"?

No. Each definition of a data type must occur at the top-level. Also,
Haskell has only a very weak record system, a deficit that is generally
agreed to be one of Haskell's greatest weaknesses.

Like jcc, I'd also be interested what concrete problem prompted your
question. While I have often found it annoying that in Haskell e.g. record
labels are global in scope, I have never encountered a situation where I
wanted to have lexically nested data type declarations.

Cheers
Ben

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[Haskell-cafe] Re: modelling C in Haskell ..

[Ben Franksen]

Galchin, Vasili wrote:
> my knowledge of point-free is from category theory. in what sense is
> Haskell point-free handle namespace pollution?

In the sense that you can write e.g.

  f = g . h

instead of

  f x = g (h x)

thereby avoiding the need to give a name the argument to f.

Cheers
Ben

BTW,
A: No.
Q: Should I include quotations after my reply?

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Re: [Haskell-cafe] hs-plugins compile error

[Don Stewart]

Thanks, 

if possible, could you construct this as a patch against the darcs
branch, which lives here:

http://code.haskell.org/~dons/code/hs-plugins

Cheers,
  Don

devriese:
> Hi,
> 
> I'm getting the compilation error that is actually logged on Hackage:
> 
> http://hackage.haskell.org/cgi-bin/hackage-scripts/package/plugins
> 
> Below is a small diff file that resolves these problems; I don't know
> what the proper protocol is for submitting these diffs but it may be
> useful to someone.
> 
> - E 
> 
> diff -ur plugins-1.2-orig/src/System/Plugins/Env.hs 
> plugins-1.2/src/System/Plugins/Env.hs
> --- plugins-1.2-orig/src/System/Plugins/Env.hs2008-06-02 
> 14:57:59.0 +0100
> +++ plugins-1.2/src/System/Plugins/Env.hs 2008-06-02 15:00:25.0 
> +0100
> @@ -73,7 +73,7 @@
>  
>  import Control.Concurrent.MVar  ( MVar(), newMVar, withMVar )
>  
> -import Distribution.Package
> +import Distribution.Package hiding (packageName)
>  import Text.ParserCombinators.ReadP
>  
>  import qualified Data.Map as M
> diff -ur plugins-1.2-orig/src/System/Plugins/PackageAPI.hs 
> plugins-1.2/src/System/Plugins/PackageAPI.hs
> --- plugins-1.2-orig/src/System/Plugins/PackageAPI.hs 2008-06-02 
> 14:57:59.0 +0100
> +++ plugins-1.2/src/System/Plugins/PackageAPI.hs  2008-06-02 
> 14:59:49.0 +0100
> @@ -40,7 +40,7 @@
>  
>  #if CABAL == 1 || __GLASGOW_HASKELL__ >= 604
>  import Distribution.InstalledPackageInfo
> -import Distribution.Package
> +import Distribution.Package hiding (depends, packageName)
>  #else
>  import System.Plugins.Package
>  #endif
> diff -ur plugins-1.2-orig/src/System/Plugins/ParsePkgConfCabal.hs 
> plugins-1.2/src/System/Plugins/ParsePkgConfCabal.hs
> --- plugins-1.2-orig/src/System/Plugins/ParsePkgConfCabal.hs  2008-06-02 
> 14:57:59.0 +0100
> +++ plugins-1.2/src/System/Plugins/ParsePkgConfCabal.hs   2008-06-02 
> 14:58:56.0 +0100
> @@ -6,7 +6,7 @@
>) where
>  
>  import Distribution.InstalledPackageInfo
> -import Distribution.Package
> +import Distribution.Package hiding (depends)
>  import Distribution.Version
>  
>  import Data.Char ( isSpace, isAlpha, isAlphaNum, isUpper, 
> isDigit )
> 
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Re: [Haskell-cafe] Re: hmatrix

[Bulat Ziganshin]

Hello Anatoly,

>> Yes, I will try to write a simple version of Data.Array.ST...
> Wouldn't it be more efficient to use StorableArray, so you can cast

there is some difference between them - MutableByteArray# (used for
STUArray) is movable Haskell object which is subject to GC while
StorableArray has a fixed address and allocated through C malloc().
this makes MBA more appropriate for small arrays while SA should be
used for large ones because GC makes memory usage of program 3 times
larger


-- 
Best regards,
 Bulatmailto:[EMAIL PROTECTED]

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Re: [Haskell-cafe] What is the maturity of Haskell Web Frameworks

[Don Stewart]

aditya_siram:
> 
> I am building a web-app that, in broad strokes, allows a leader to
> assign tasks to team members and allows team members to
> accept/reject/pick tasks that they want to do. 
> 
> I really like Haskell and I would like to use it to implement the
> solution. Are frameworks like Happs ready? Not so much in terms of
> documentation, but in functionality and stability. 

HAppS is nice (see hpaste.org for example, which is nice and simple, and
has been running for over a year).

Another nice option in Haskell is using something like HStringTemplate
or the xhtml combinators  with fastcgi hooked into GHC's concurrency
mechanisms.

You can find *many* more things here,

http://hackage.haskell.org/packages/archive/pkg-list.html#cat:Network
http://hackage.haskell.org/packages/archive/pkg-list.html#cat:Web
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[Haskell-cafe] Re: hmatrix

[Anatoly Yakovenko]

>> do you have any plans to provide an interface for inplace updates?
>
> Yes, I will try to write a simple version of Data.Array.ST...
>

I can try to help you, although I still dont quite grok monads.
Wouldn't it be more efficient to use StorableArray, so you can cast
from and to C?  I am not sure how vectors and matrixes are represented
in C, but I imagine it should be possible to manipulate them without
resorting to copying between haskell and C.
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[Haskell-cafe] Re: cabal install fail for happs-hsp-template

[Thomas Hartman]

I just noticed this is also reported as a 6.8 build failure on hackage itself.

http://hackage.haskell.org/cgi-bin/hackage-scripts/package/happs-hsp-template

2008/6/2 Thomas Hartman <[EMAIL PROTECTED]>:
> Can cabal install be made to work for this package?
> *
> [EMAIL PROTECTED]:~>sudo cabal install happs-hsp-template
> [sudo] password for thartman:
> cabal: internal error: could not construct a valid install plan.
> The proposed (invalid) plan contained the following problems:
> Package Cabal is required by several packages, but they require
> inconsistent versions:
>  package ghc-6.8.2 requires Cabal-1.2.3.0
>  package plugins-1.2 requires Cabal-1.5.2
>
>
> [EMAIL PROTECTED]:~>cabal --version
> cabal-install version 0.4.7
> using version 1.3.11 of the Cabal library
> [EMAIL PROTECTED]:~>ghc --version
> The Glorious Glasgow Haskell Compilation System, version 6.8.2
> [EMAIL PROTECTED]:~>ghc-pkg list | grep -i ghc
> /usr/local/lib/ghc-6.8.2/package.conf:
>(ghc-6.8.2), haskell-src-1.0.1.1, haskell98-1.0.1.0, hpc-0.5.0.0,
>
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[Haskell-cafe] cabal install fail for happs-hsp-template

[Thomas Hartman]

Can cabal install be made to work for this package?
*
[EMAIL PROTECTED]:~>sudo cabal install happs-hsp-template
[sudo] password for thartman:
cabal: internal error: could not construct a valid install plan.
The proposed (invalid) plan contained the following problems:
Package Cabal is required by several packages, but they require
inconsistent versions:
  package ghc-6.8.2 requires Cabal-1.2.3.0
  package plugins-1.2 requires Cabal-1.5.2


[EMAIL PROTECTED]:~>cabal --version
cabal-install version 0.4.7
using version 1.3.11 of the Cabal library
[EMAIL PROTECTED]:~>ghc --version
The Glorious Glasgow Haskell Compilation System, version 6.8.2
[EMAIL PROTECTED]:~>ghc-pkg list | grep -i ghc
/usr/local/lib/ghc-6.8.2/package.conf:
(ghc-6.8.2), haskell-src-1.0.1.1, haskell98-1.0.1.0, hpc-0.5.0.0,
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Re: [Haskell-cafe] Damnit, we need a CPAN.

[Thomas Schilling]

On 29 maj 2008, at 18.13, Don Stewart wrote:


Hackage and Cabal are nice, but a command line tool for automatically
searching Hackage and installing Hackage packages (like the cpan
program, or easy_install) would be nice.  Unless I haven't done my
homework and this tool exists...



This tool exists. It is called 'cabal-install'. To try out one of
today's new packages:

$ cabal update
$ cabal install category-extras




Another nice feature:  Say you want to hack on the darcs version of a  
project, but you need to install the dependencies.  If the project is  
Cabalised you can build and install the darcs version as well as all  
dependencies by calling 'cabal install' with no arguments inside the  
project directory.


  $ darcs get 
  $ cd 
  $ cabal install

/ Thomas
--
Push the envelope.  Watch it bend.





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Re: [Haskell-cafe] What is the maturity of Haskell Web Frameworks

[Marc Weber]

On Mon, Jun 02, 2008 at 09:37:11AM -0500, Aditya Siram wrote:
> 
> I am building a web-app that, in broad strokes, allows a leader to assign 
> tasks to team members and allows team members to accept/reject/pick tasks 
> that they want to do. 
> 
> I really like Haskell and I would like to use it to implement the solution. 
> Are frameworks like Happs ready? Not so much in terms of documentation, but 
> in functionality and stability. 
Me too, but in this case if it's only about assigning tasks you should
consider using existing solutions such as flysrpay or mantis 
http://www.mantisbt.org/
Maybe they fit your needs ?

mit freundlichem Gruss
Marc Weber
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Re: [Haskell-cafe] What is the maturity of Haskell Web Frameworks

[Daniel Patterson]

You definitely could use HAppS for that, but considering that it sounds like a
pretty small/lightweight app, you might want to check out hvac
( http://fmapfixreturn.wordpress.com/2008/03/23/ ), which is a newer (but
still surprisingly full-featured) web framework. It is pretty
lightweight, and might be easier to get working for your purposes.

Daniel

On Mon, 2 Jun 2008 09:37:11 -0500
Aditya Siram <[EMAIL PROTECTED]> wrote:

> 
> I am building a web-app that, in broad strokes, allows a leader to assign
> tasks to team members and allows team members to accept/reject/pick tasks
> that they want to do. 
> 
> I really like Haskell and I would like to use it to implement the solution.
> Are frameworks like Happs ready? Not so much in terms of documentation, but
> in functionality and stability. 
> 
> -Deech
> _
> Give to a good cause with every e-mail. Join the i’m Initiative from
> Microsoft. http://im.live.com/Messenger/IM/Join/Default.aspx?souce=EML_WL_
> GoodCause___ Haskell-Cafe mailing
> list Haskell-Cafe@haskell.org
> http://www.haskell.org/mailman/listinfo/haskell-cafe
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Re: [Haskell-cafe] Default definitions for associated type synonyms

[Stefan Holdermans]

Isaac,

Does anyone know if it is possible to specify a default definition  
for an

associated type synonym?



According to http://hackage.haskell.org/trac/ghc/wiki/TypeFunctionsStatus 
 defaults for associated types is still a TODO.


Cheers,

  Stefan
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Re: [Haskell-cafe] Default definitions for associated type synonyms

[Isaac Dupree]

Dreixel wrote:

Hello,

Does anyone know if it is possible to specify a default definition for an
associated type synonym? When I tried:

class A a where

  type B a = a



GHC (version 6.9.20080309) told me: "Type declaration in a class must be a
kind signature or synonym default". However, when I look at the parser I see
no way to specify such synonym default. Is this possible?


I'm curious... so, cc'ing glasgow-haskell-users mailinglist because the 
question is more likely to be noticed by relevant people there.



Thanks,
Zé Pedro

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[Haskell-cafe] What is the maturity of Haskell Web Frameworks

[Aditya Siram]

I am building a web-app that, in broad strokes, allows a leader to assign tasks 
to team members and allows team members to accept/reject/pick tasks that they 
want to do. 

I really like Haskell and I would like to use it to implement the solution. Are 
frameworks like Happs ready? Not so much in terms of documentation, but in 
functionality and stability. 

-Deech
_
Give to a good cause with every e-mail. Join the i’m Initiative from Microsoft.
http://im.live.com/Messenger/IM/Join/Default.aspx?souce=EML_WL_ 
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Re: [Haskell-cafe] Re: Damnit, we need a CPAN.

[Wolfgang Jeltsch]

Am Freitag, 30. Mai 2008 22:09 schrieb Achim Schneider:
> […]

> I'm generally very interested in declarative GUI programming, but not
> nearly enough acquainted with the whole topic to judge one project's
> approach over the other. I just followed standard scientific evaluation
> technique to select the projects to consider: The ones with the most and
> most recent activity win.
>
> So far, my impression is that documentation is severely lacking, but
> then I'm too busy watching Babylon 5 right now and did not get more
> than half an hour or so looking at grapefruit.

Okay, I think we’ll improve API documentation and then make a release, despite 
Grapefruit not being production quality yet.  I hope, you’ll find it 
useful. :-) 

Best wishes,
Wolfgang
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Re: [Haskell-cafe] Mutually Recursive Modules

[Isaac Dupree]

Richard Giraud wrote:

Hello

I'm using GHC 6.8.2 with mutally recursive modules.  I'm familiar with 
how to do simple cases in GHC ({-# SOURCE #-} and .hs-boot files) but I 
can't figure out how to get it to work for a particular set of modules.


Is it known (i.e., proven) that GHC 6.8.2 can compile any set of 
mutually recursive modules without refactoring?  Are there known 
limitations?


With the old (6.2 and before) .hi-boot scheme where there was no 
abstraction in boot-files, it could probably do anything that it could 
do.  But I'm not convinced with .hs-boot... it can resolve one level of 
cycle, and I don't know how to *prove* that it *can't* do any given 
thing, but I strongly suspect there are things it can't do.  Luckily, it 
is very often the case that your code will be better off anyway if 
refactored to have less module recursion. (though not always.)


-Isaac
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[Haskell-cafe] Mutually Recursive Modules

[Richard Giraud]

Hello

I'm using GHC 6.8.2 with mutally recursive modules.  I'm familiar with 
how to do simple cases in GHC ({-# SOURCE #-} and .hs-boot files) but I 
can't figure out how to get it to work for a particular set of modules.


Is it known (i.e., proven) that GHC 6.8.2 can compile any set of 
mutually recursive modules without refactoring?  Are there known 
limitations?


Thanks,

Richard G.
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[Haskell-cafe] hs-plugins compile error

[Edsko de Vries]

Hi,

I'm getting the compilation error that is actually logged on Hackage:

http://hackage.haskell.org/cgi-bin/hackage-scripts/package/plugins

Below is a small diff file that resolves these problems; I don't know
what the proper protocol is for submitting these diffs but it may be
useful to someone.

- E 

diff -ur plugins-1.2-orig/src/System/Plugins/Env.hs 
plugins-1.2/src/System/Plugins/Env.hs
--- plugins-1.2-orig/src/System/Plugins/Env.hs  2008-06-02 14:57:59.0 
+0100
+++ plugins-1.2/src/System/Plugins/Env.hs   2008-06-02 15:00:25.0 
+0100
@@ -73,7 +73,7 @@
 
 import Control.Concurrent.MVar  ( MVar(), newMVar, withMVar )
 
-import Distribution.Package
+import Distribution.Package hiding (packageName)
 import Text.ParserCombinators.ReadP
 
 import qualified Data.Map as M
diff -ur plugins-1.2-orig/src/System/Plugins/PackageAPI.hs 
plugins-1.2/src/System/Plugins/PackageAPI.hs
--- plugins-1.2-orig/src/System/Plugins/PackageAPI.hs   2008-06-02 
14:57:59.0 +0100
+++ plugins-1.2/src/System/Plugins/PackageAPI.hs2008-06-02 
14:59:49.0 +0100
@@ -40,7 +40,7 @@
 
 #if CABAL == 1 || __GLASGOW_HASKELL__ >= 604
 import Distribution.InstalledPackageInfo
-import Distribution.Package
+import Distribution.Package hiding (depends, packageName)
 #else
 import System.Plugins.Package
 #endif
diff -ur plugins-1.2-orig/src/System/Plugins/ParsePkgConfCabal.hs 
plugins-1.2/src/System/Plugins/ParsePkgConfCabal.hs
--- plugins-1.2-orig/src/System/Plugins/ParsePkgConfCabal.hs2008-06-02 
14:57:59.0 +0100
+++ plugins-1.2/src/System/Plugins/ParsePkgConfCabal.hs 2008-06-02 
14:58:56.0 +0100
@@ -6,7 +6,7 @@
   ) where
 
 import Distribution.InstalledPackageInfo
-import Distribution.Package
+import Distribution.Package hiding (depends)
 import Distribution.Version
 
 import Data.Char ( isSpace, isAlpha, isAlphaNum, isUpper, isDigit )

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Re: [Haskell-cafe] [ANNOUNCE] git-darcs-import 0.1

[Bertram Felgenhauer]

Thomas Schilling wrote:
>
> On 1 jun 2008, at 20.44, Bertram Felgenhauer wrote:
[git-darcs-import]
>
> Nice!  Do you happen to also have a darcs (or Git) repository somewhere?

I've uploaded my (git) repo to repo.or.cz, see
http://repo.or.cz/w/git-darcs-import.git

Patches are welcome.

enjoy,

Bertram
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Re: [Haskell-cafe] [ANNOUNCE] git-darcs-import 0.1

[Thomas Schilling]

On 1 jun 2008, at 20.44, Bertram Felgenhauer wrote:


Hi,

I'm pleased to announce yet another tool for importing darcs  
repositories

to git. Unlike darcs2git [1] and darcs-to-git [2], it's written in
Haskell, on top of the darcs2 source code. The result is a much faster
program - it can convert the complete ghc 6.9 branch (without  
libraries)
in less than 15 minutes on my slightly dated machine (Athlon XP 2500 
+),

which is quite fast [3]. Incremental updates work, too.


Nice!  Do you happen to also have a darcs (or Git) repository somewhere?

/ Thomas
--
Monkey killing monkey killing monkey over pieces of the ground.
Silly monkeys give them thumbs they forge a blade
And where there's one they're bound to divide it
Right in two



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Re: [Haskell-cafe] ghc 6.8.2 issue

[Duncan Coutts]

On Mon, 2008-06-02 at 00:07 -0500, Galchin, Vasili wrote:
> Hello,
> 
>   I have been developing new code for the "unix" package. I have
> run into what I think are ghc 6.8.2 anomalies but couldn't see a
> pattern. Possibly now I do. I have been using the 32-bit x86 ghc
> binary that I downloaded from http://www.haskell.org and running on
> Ubuntu Linux. I am pretty I can repeat now. Everything is ok until I
> do "sudo runhaskell Setup.hs install" which installs a new "unix"
> package that I just built. Of course the "intall" installs
> into /usr/local/lib/unix-2.3.0.0/ghc-6.8.2. The "install" seems to
> destroy some ghc compiler state under /usr/local ...

That sounds right. You're replacing the unix-2.3.0.0 library that comes
with ghc-6.8.2 with your own version. It is highly unlikely to be ABI
compatible with the one you are replacing and so all the other packages
that already depends on the existing unix-2.3.0.0 library end up broken.
You'd expect this kind of breakage to be exposed as link errors and
segfaults.

I suggest you do not replace any of the libraries that come with ghc. To
be more precise, it is perfectly ok to *add new versions* but it is not
ok to *replace existing versions* without rebuilding all the other libs
that depend on it.

Make sense?

So if you really want to make changes to the unix lib, make sure you
change the version number too. I also suggest not installing the
packages as root, just install them locally. That way you can guarantee
you never mess up your ghc install. You would be able to revert to a
clean ghc install just by removing your
~/.ghc/$arch/ghc-6.8.2/package.conf file which will unregister *all*
locally registered packages. To unregister individual packages use
ghc-pkg --user unregister $pkgname

Duncan

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[Haskell-cafe] Re: hmatrix

[Alberto Ruiz]

Anatoly Yakovenko wrote:

do you have any plans to provide an interface for inplace updates?


Yes, I will try to write a simple version of Data.Array.ST...


On Sun, Jun 1, 2008 at 3:20 AM, Alberto Ruiz <[EMAIL PROTECTED]> wrote:

Anatoly Yakovenko wrote:

What is the most efficient way to update a position in a matrix or a
vector?  I came up with this:

updateVector :: Vector Double -> Int -> Double -> Vector Double
updateVector vec pos val = vec `add` v2
  where
 v2 = fromList $ (replicate (pos) 0.0) ++ ((val - (vec @>
pos)):(replicate ((dim vec)- pos - 1) 0.0))

but this seems pretty inefficient to me.

thanks,
Anatoly


It is probably more efficient to use subVector and join (implemented by
copyArray):

updateVector' v pos val
   | pos == 0= join [b,c]
   | pos == dim v -1 = join [a,b]
   | otherwise   = join [a,b,c]
   where a = subVector 0 pos v
 b = fromList [val]
 c = subVector (pos+1) (dim v -pos-1) v


updateVector' (fromList [1,2,3,4,5]) 2 57

5 |> [1.0,2.0,57.0,4.0,5.0]

(The three cases are required because empty vectors are not currently
allowed.)

Something similar can be done for matrices using flatten and reshape.

Although vectors and matrices in this library are immutable and intended to
be manipulated as a whole by higher level functions, this kind of update
functions may often be useful. I will include them soon.

Alberto




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Re: [Haskell-cafe] GHCi panic

[Jules Bean]

Andrew Coppin wrote:

I don't suppose this will surprise anybody greatly, but...

Apparently if you write a Haskell module that is 400 KB in size and 
defines a single CAF consisting of a 45,000-element [String], GHCi 
panics when attempting to load it interpretted, and hits a stack 
overflow attempting to load it compiled.


qv http://hackage.haskell.org/trac/ghc/ticket/2002
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Re: [Haskell-cafe] Re: Images and GUIs in Haskell

[Yann Golanski]

Quoth Achim Schneider on Sun, Jun 01, 2008 at 04:09:10 +0200
> I would go for GL(U(T)), as it's as good for 2d primitives as SDL will
> ever be, has excellent cross-platform support and allows you to go 3d
> if you want to. There's also some very decent event handling.

You can use R as well. http://www.r-project.org/

-- 
[EMAIL PROTECTED] -= H+ =- www.kierun.org
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