[arch-haskell] help upgrading packages

[Bardur Arantsson]

On 2014-05-15 11:35, Magnus Therning wrote:
> On Wed, May 14, 2014 at 10:47 PM, Bardur Arantsson <spam at scientician.net> wrote:
>> On 2014-05-12 15:47, Magnus Therning wrote:
>> [--snip--]
>>
>> All I needed to install build-wrapper (which I think was the inital
>> "problem" package in this thread) was to do
>>
>> $ mkdir somewhere/buildwrapper
>> $ cd somewhere/buildwrapper
>> $ cabal sandbox init
>> $ cabal install buildwrapper
>>
>> Add "somewhere/buildwrapper" to $PATH. Bonus points for using "stow" or
>> similar.
>> The key point in the above recipe is to *NOT* have all kinds of
>> libraries installed system-wide (aka. via pacman). It usually works
>> better that way.
> 
> Surely you should then `cabal install` the tool so you don't end up
> with a complete sandbox with every dependency of buildwrapper's in it,
> no?
> 

You *do* need to keep the sandbox around (or at least parts of it).
That's where the last "cabal install" line installs to.

> For some packages you would have to keep the sandbox around and do it
> your way though, e.g. `pandoc` since it contains both a library and
> executables.
> 

If you want to use a sandboxed thing as a library then you need to
develop "inside" the sandbox, so e.g. you'd just create a little cabal
file for your project which declares all the dependencies and use cabal
to build your project.

>> Disclaimer: I haven't actually used buildwrapper personally, but one
>> assumes that it just acts as an executable and doesn't install things
>> into its own environment or other weird things.
> 
> Personally I think `cabal` really shines when doing more serious
> Haskell development than I do.  I never test my Haskell packages on
> anything other than the GHC that's in [haskell-core], and neither do I
> test them against any other versions of packages than what's found in
> [haskell-core].  My Haskell development is completely in my free time
> and for fun.  I think that if I ever am lucky enough find myself using
> Haskell professionally I'd quickly see more use in what `cabal` has to
> offer.
> 

Cabal also works beautifully for "hobby" type development. Once you've
created a cabal file you hardly ever need to touch it again. :)

Regards,