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Today's Topics:

   1.  Question about ghc and cabal: finding packages (C Gosch)
   2. Re:  Question about ghc and cabal: finding packages
      (Mathew de Detrich)
   3. Re:  Question about ghc and cabal: finding packages
      (Henk-Jan van Tuyl)
   4.  forM vs mapM (Gaius Hammond)
   5. Re:  forM vs mapM (Thomas Davie)
   6. Re:  forM vs mapM (Gaius Hammond)
   7. Re:  Question about ghc and cabal: finding packages
      (Jonas Almstr?m Dureg?rd)
   8. Re:  Question about ghc and cabal: finding packages
      (Daniel Fischer)


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

Message: 1
Date: Thu, 19 Aug 2010 09:12:49 +0200
From: C Gosch <ch.go...@googlemail.com>
Subject: [Haskell-beginners] Question about ghc and cabal: finding
        packages
To: beginners@haskell.org
Message-ID:
        <aanlktimn5n7hwaxr32kzg7h7j3n+4mj7aa6ak-gss...@mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"

Hi everyone,
I have installed ghc 6.12.3 and the Haskell platform; now, when I install
packages from hackage using
   cabal install <package-name>,
they get installed in ~/.cabal,
which is fair enough.
However, when I call a
   runhaskell Setup.lhs configure
that used to work on a different computer with the same software setup,
ghc (or is it cabal?) complains that it cannot find the packages I have just
installed.
Checking again revealed that they are indeed installed, just not in the ghc
installation directory,
but under ~/.cabal.
How can I tell cabal and/or ghc where to look for libraries?

Thanks, again, for any help!
Christian
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Message: 2
Date: Thu, 19 Aug 2010 07:57:50 +0000
From: Mathew de Detrich <dete...@gmail.com>
Subject: Re: [Haskell-beginners] Question about ghc and cabal: finding
        packages
To: C Gosch <ch.go...@googlemail.com>
Cc: beginners@haskell.org
Message-ID:
        <aanlktink1dp7h_jvpcni0nmk8guugukb82xciglcs...@mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"

If you install a package through cabal install, it will automatically
register with GHC (it works the same way that gems works on ruby for
example)

Using runhaskell <commands> is whats used when manually building/configuring
packages (for example creating archlinux packages from cabal packages from
hackage) or when you are developing and creating cabal packages yourself

(in other words, when you do cabal install, cabal internally does all the
commands for configuring/checking dependencies/building and installing)

So you should be able to use use the package instantly after you install it
(you can also use ghc-pkg list to check all installed packages)
On Thu, Aug 19, 2010 at 7:12 AM, C Gosch <ch.go...@googlemail.com> wrote:

> Hi everyone,
> I have installed ghc 6.12.3 and the Haskell platform; now, when I install
> packages from hackage using
>    cabal install <package-name>,
> they get installed in ~/.cabal,
> which is fair enough.
> However, when I call a
>    runhaskell Setup.lhs configure
> that used to work on a different computer with the same software setup,
> ghc (or is it cabal?) complains that it cannot find the packages I have
> just installed.
> Checking again revealed that they are indeed installed, just not in the ghc
> installation directory,
> but under ~/.cabal.
> How can I tell cabal and/or ghc where to look for libraries?
>
> Thanks, again, for any help!
> Christian
>
>
> _______________________________________________
> Beginners mailing list
> Beginners@haskell.org
> http://www.haskell.org/mailman/listinfo/beginners
>
>
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------------------------------

Message: 3
Date: Thu, 19 Aug 2010 11:06:40 +0200
From: "Henk-Jan van Tuyl" <hjgt...@chello.nl>
Subject: Re: [Haskell-beginners] Question about ghc and cabal: finding
        packages
To: beginners@haskell.org, "C Gosch" <ch.go...@googlemail.com>
Message-ID: <op.vhogxequpz0...@zen5.router.home>
Content-Type: text/plain; charset=iso-8859-15; format=flowed;
        delsp=yes

On Thu, 19 Aug 2010 09:12:49 +0200, C Gosch <ch.go...@googlemail.com>  
wrote:

> Hi everyone,
> I have installed ghc 6.12.3 and the Haskell platform; now, when I install
> packages from hackage using
>    cabal install <package-name>,
> they get installed in ~/.cabal,
> which is fair enough.
> However, when I call a
>    runhaskell Setup.lhs configure
> that used to work on a different computer with the same software setup,
> ghc (or is it cabal?) complains that it cannot find the packages I have  
> just
> installed.
> Checking again revealed that they are indeed installed, just not in the  
> ghc
> installation directory,
> but under ~/.cabal.
> How can I tell cabal and/or ghc where to look for libraries?
>
> Thanks, again, for any help!
> Christian

The command "cabal install " installs a package locally by default,  
whereas "runhaskell Setup" installs globally. When installing globally,  
the local packages are ignored.

Regards,
Henk-Jan van Tuyl


-- 
http://Van.Tuyl.eu/
http://members.chello.nl/hjgtuyl/tourdemonad.html
--


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

Message: 4
Date: Thu, 19 Aug 2010 10:02:22 +0000
From: "Gaius Hammond" <ga...@gaius.org.uk>
Subject: [Haskell-beginners] forM vs mapM
To: "Haskell Beginners List" <beginners@haskell.org>
Message-ID:
        
<128061004-1282212139-cardhu_decombobulator_blackberry.rim.net-2030406...@bda240.bisx.produk.on.blackberry>
        
Content-Type: text/plain

Hi all,


Can anyone give me an example of a situation where you would use forM but *not* 
mapM or vice versa? As far as I can see one is simply a flip of the other. Does 
forM make any guarantees about order of execution?


Thanks,


G



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


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

Message: 5
Date: Thu, 19 Aug 2010 11:08:34 +0100
From: Thomas Davie <tom.da...@gmail.com>
Subject: Re: [Haskell-beginners] forM vs mapM
To: ga...@gaius.org.uk
Cc: Haskell Beginners List <beginners@haskell.org>
Message-ID: <8d722972-3edb-48ad-b853-061df513f...@gmail.com>
Content-Type: text/plain; charset=us-ascii


On 19 Aug 2010, at 11:02, Gaius Hammond wrote:

> Hi all,
> 
> 
> Can anyone give me an example of a situation where you would use forM but 
> *not* mapM or vice versa? As far as I can see one is simply a flip of the 
> other. Does forM make any guarantees about order of execution?

Nope, no extra guarentees, just reverses the argument order.

forM can look quite nice if you have a large function that you want to map...

forM [someList]
  lots of
  large function
  here
  ...

while mapM can look good if you have a small function...
mapM simpleFunction [someList]

They're also useful both ways round partially applied.

Bob

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

Message: 6
Date: Thu, 19 Aug 2010 10:16:06 +0000
From: "Gaius Hammond" <ga...@gaius.org.uk>
Subject: Re: [Haskell-beginners] forM vs mapM
To: "Thomas Davie" <tom.da...@gmail.com>
Cc: Haskell Beginners List <beginners@haskell.org>
Message-ID:
        
<712809430-1282212964-cardhu_decombobulator_blackberry.rim.net-7039081...@bda240.bisx.produk.on.blackberry>
        
Content-Type: text/plain

Thanks, I suspected that might be the case but it seemed too simple :-)



Cheers,



G



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

-----Original Message-----
From: Thomas Davie <tom.da...@gmail.com>
Date: Thu, 19 Aug 2010 11:08:34 
To: <ga...@gaius.org.uk>
Cc: Haskell Beginners List<beginners@haskell.org>
Subject: Re: [Haskell-beginners] forM vs mapM


On 19 Aug 2010, at 11:02, Gaius Hammond wrote:

> Hi all,
> 
> 
> Can anyone give me an example of a situation where you would use forM but 
> *not* mapM or vice versa? As far as I can see one is simply a flip of the 
> other. Does forM make any guarantees about order of execution?

Nope, no extra guarentees, just reverses the argument order.

forM can look quite nice if you have a large function that you want to map...

forM [someList]
  lots of
  large function
  here
  ...

while mapM can look good if you have a small function...
mapM simpleFunction [someList]

They're also useful both ways round partially applied.

Bob

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

Message: 7
Date: Thu, 19 Aug 2010 13:19:26 +0200
From: Jonas Almstr?m Dureg?rd <jonas.dureg...@chalmers.se>
Subject: Re: [Haskell-beginners] Question about ghc and cabal: finding
        packages
To: C Gosch <ch.go...@googlemail.com>
Cc: beginners@haskell.org
Message-ID:
        <aanlktinjabxeyros8avfoxjtulwgiksru4ctcpk3b...@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1

Try simply

cabal configure

in the directory where Setup.lhs (and your .cabal file) is located.

/J

On 19 August 2010 09:12, C Gosch <ch.go...@googlemail.com> wrote:
> Hi everyone,
> I have installed ghc 6.12.3 and the Haskell platform; now, when I install
> packages from hackage using
>    cabal install <package-name>,
> they get installed in ~/.cabal,
> which is fair enough.
> However, when I call a
>    runhaskell Setup.lhs configure
> that used to work on a different computer with the same software setup,
> ghc (or is it cabal?) complains that it cannot find the packages I have just
> installed.
> Checking again revealed that they are indeed installed, just not in the ghc
> installation directory,
> but under ~/.cabal.
> How can I tell cabal and/or ghc where to look for libraries?
>
> Thanks, again, for any help!
> Christian
>
>
> _______________________________________________
> Beginners mailing list
> Beginners@haskell.org
> http://www.haskell.org/mailman/listinfo/beginners
>
>


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

Message: 8
Date: Thu, 19 Aug 2010 14:14:44 +0200
From: Daniel Fischer <daniel.is.fisc...@web.de>
Subject: Re: [Haskell-beginners] Question about ghc and cabal: finding
        packages
To: beginners@haskell.org
Cc: C Gosch <ch.go...@googlemail.com>
Message-ID: <201008191414.44647.daniel.is.fisc...@web.de>
Content-Type: text/plain;  charset="iso-8859-1"

On Thursday 19 August 2010 13:19:26, Jonas Almström Duregård wrote:
> Try simply
>
> cabal configure
>
> in the directory where Setup.lhs (and your .cabal file) is located.
>
> /J

Or, to configure, build and install in one go, just `cabal install' in that 
directory.
If you want to go the runhaskell Setup.[l]hs road, however, you have to 
pass the --user flag to runhaskell Setup.[l]hs configure if you need 
packages from your user db.
Or you have to reinstall the cabal-installed packages globally (surprise: 
pass the --global flag to cabal install), perhaps set `user-install: False' 
in ~/.cabal/config if you want to have global installs by default.

>
> On 19 August 2010 09:12, C Gosch <ch.go...@googlemail.com> wrote:
> > Hi everyone,
> > I have installed ghc 6.12.3 and the Haskell platform; now, when I
> > install packages from hackage using
> >    cabal install <package-name>,
> > they get installed in ~/.cabal,
> > which is fair enough.
> > However, when I call a
> >    runhaskell Setup.lhs configure
> > that used to work on a different computer with the same software
> > setup, ghc (or is it cabal?) complains that it cannot find the
> > packages I have just installed.
> > Checking again revealed that they are indeed installed, just not in
> > the ghc installation directory,
> > but under ~/.cabal.
> > How can I tell cabal and/or ghc where to look for libraries?
> >
> > Thanks, again, for any help!
> > Christian
> >


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

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