gmane.comp.lang.haskell.libraries

Peter Gammie | 6 Dec 11:33

Cabal, System.Filepath

To my surprise, if you type ^C at the right moment you can trash GHC's  
(system-wide) package list. I figured it was easier to reinstall than  
fix, but forgot Debian installs GHC 6.6 if I don't ask for "unstable".  
So, let's get Cabal on its feet again:

$ ghc --version
The Glorious Glasgow Haskell Compilation System, version 6.6

$ darcs pull
Pulling from "http://darcs.haskell.org/cabal"...
No remote changes to pull in!

$ ghc -i. --make Setup.lhs -o setup

Distribution/Simple.hs:114:7:
     Could not find module `System.FilePath':
       Use -v to see a list of the files searched for.

Can I humbly suggest that Cabal rely on very few external libraries?

(I'm switching to 6.6.1 as I type this.)

cheers
peter

headers

Duncan Coutts | 6 Dec 12:56

Re: Cabal, System.Filepath

On Thu, 2007-12-06 at 17:35 +0700, Peter Gammie wrote:
> To my surprise, if you type ^C at the right moment you can trash GHC's  
> (system-wide) package list. I figured it was easier to reinstall than  
> fix, but forgot Debian installs GHC 6.6 if I don't ask for "unstable".  
> So, let's get Cabal on its feet again:

Debian actually installs a backup of the global package.conf file. It's
called package.conf.shipped or something like that.

> $ ghc --version
> The Glorious Glasgow Haskell Compilation System, version 6.6
> 
> $ darcs pull
> Pulling from "http://darcs.haskell.org/cabal"...
> No remote changes to pull in!
> 
> $ ghc -i. --make Setup.lhs -o setup
> 
> Distribution/Simple.hs:114:7:
>      Could not find module `System.FilePath':
>        Use -v to see a list of the files searched for.
> 
> Can I humbly suggest that Cabal rely on very few external libraries?

We recently defined filepath to be a core library. As you point out
however this does pose a problem for older compilers. Fortunately it's
not that bad, you can build and install filepath using the older cabal
that comes with your older compiler. If that's not possible for whatever
reason you can download both Cabal and filepath and:

(Continue reading)

headers

Peter Gammie | 6 Dec 15:44

Re: Cabal, System.Filepath

On 06/12/2007, at 6:56 PM, Duncan Coutts wrote:

> On Thu, 2007-12-06 at 17:35 +0700, Peter Gammie wrote:
>> Can I humbly suggest that Cabal rely on very few external libraries?
>
> We recently defined filepath to be a core library. As you point out
> however this does pose a problem for older compilers. Fortunately it's
> not that bad, you can build and install filepath using the older cabal
> that comes with your older compiler. If that's not possible for  
> whatever
> reason you can download both Cabal and filepath and:
>
> ghc -i../filepath --make Setup.lhs -o setup

I realise all this, I just wanted to log the fact that darcs-Cabal  
does not build on GHC 6.6. I thought it was a design goal for Cabal to  
compile on all GHCs back to 6.4.x (or something). No matter, I  
installed GHC 6.6.1:

$ ghc --version
The Glorious Glasgow Haskell Compilation System, version 6.6.1

Next problem: let's reinstall the 'cgi' package (latest from darcs):

$ ghc-pkg list
/usr/lib/ghc-6.6.1/package.conf:
     Cabal-1.1.6.2, Cabal-1.3.1, base-2.1.1, filepath-1.0, (ghc-6.6.1),
     haskell98-1.0, parsec-2.0, readline-1.0, regex-base-0.72,
     regex-compat-0.71, regex-posix-0.71, rts-1.0, stm-2.0,
     template-haskell-2.1, unix-2.1

(Continue reading)

headers

Duncan Coutts | 6 Dec 23:40

Re: Cabal, System.Filepath


On Thu, 2007-12-06 at 21:44 +0700, Peter Gammie wrote:
> On 06/12/2007, at 6:56 PM, Duncan Coutts wrote:
> 
> > On Thu, 2007-12-06 at 17:35 +0700, Peter Gammie wrote:
> >> Can I humbly suggest that Cabal rely on very few external libraries?
> >
> > We recently defined filepath to be a core library. As you point out
> > however this does pose a problem for older compilers. Fortunately it's
> > not that bad, you can build and install filepath using the older cabal
> > that comes with your older compiler. If that's not possible for  
> > whatever reason you can download both Cabal and filepath and:
> >
> > ghc -i../filepath --make Setup.lhs -o setup
> 
> I realise all this, I just wanted to log the fact that darcs-Cabal  
> does not build on GHC 6.6. I thought it was a design goal for Cabal to  
> compile on all GHCs back to 6.4.x (or something).

I have considered bundling filepath for exactly this reason. I'm still
undecided.

> Why is ghc-pkg looking only at globally-installed packages?

It's not ghc-pkg, it's Cabal that by default only looks at the global
packages. You can configure with --user to have it look at the user
ones. Personally I'm in favour of switching the default to --user.

Of course it cannot use user packages and then install globally, and the
current default prefix is /usr/local which is usually root only, so if

(Continue reading)

headers

Peter Gammie | 7 Dec 01:24

Re: Cabal, System.Filepath

On 07/12/2007, at 5:40 AM, Duncan Coutts wrote:
> On Thu, 2007-12-06 at 21:44 +0700, Peter Gammie wrote:
>> Why is ghc-pkg looking only at globally-installed packages?
>
> It's not ghc-pkg, it's Cabal that by default only looks at the global
> packages. You can configure with --user to have it look at the user
> ones. Personally I'm in favour of switching the default to --user.
>
> Of course it cannot use user packages and then install globally, and  
> the
> current default prefix is /usr/local which is usually root only, so if
> we switch the default to user installs then we'd have to switch the
> default prefix. I'd prefer that too though. However it's a change that
> would require general consensus.

Ah, I see. I didn't realise configure had a --user switch as well.

A stop-gap might be to generate a more helpful error message:

ghc-pkg --global list
<check for deps>
if unsatisfied dep
   ghc-pkg list
   if dep is satisfied now, print "Perhaps configure with --user?"

IMH and not so informed opinion, I think the defaults should be close  
to autoconf's, if only by the principle of least surprise.

Thanks!

(Continue reading)