cvs commit: fptools/libraries/HaXml HaXml.cabal configure fptools/libraries/HaXml/src Makefile

[Simon Marlow]

On 18 April 2005 16:31, Malcolm Wallace wrote:

> Ross Paterson <ross at soi.city.ac.uk> writes:
> 
>>> I have to admit I haven't been following the development of Cabal
>>> too closely.  I am still using my own Makefiles to build HaXml, and
>>> these tweaks only affect that process.
>> 
>> You added depends and hs-libraries fields to the top-level .cabal
>> file, which triggers a parse error.
> 
> OK, I see.  Easy enough to fix.  Any idea why the 'depends' field is
> distinct from the 'build-depends' field?  I can't immediately think of
> a situation in which they would differ.  (The extra fields I added
> were exactly those given to me by a user filing a bug report.)

depends specifies exact packages, whereas build-depends specifies
version ranges.  eg. you might have

   build-depends: base>=1.0

in the .cabal file, which might give rise to

  depends: base-1.1

in the InstalledPackageInfo (i.e. the input to ghc-pkg, which you don't
see if you're using Cabal's build system).  Currently, ghc-pkg lets you
omit the version numbers in the depends field, filling it in with
whatever version is installed.  But that will go wrong if the package is
shipped to another location which has a different version installed, or
multiple versions.

Cheers,
	Simon