trouble with Debian package ghc5

[Michael Weber]

* Norman Ramsey <nr at eecs.harvard.edu> [2002-05-27T19:12-0400]:
> I'm trying to compile some Haskell code using Debian package ghc5,
> and it fails to find -lreadline at link time.  Looks like a config
> problem because hte library is sitting there in /lib.

You also need the libreadline4-dev package to compile stuff against
readline (but see below).  Can you please check whether it is
installed?

> I'm cc-ing the GHC bug list even though this looks to me like a Debian
> problem.

>From looking at http://bugs.debian.org/134950, it _seemed_ to me only
ghc package util needed readline to link, and that wouldn't
necessarily warrant a dependency on libreadline*-dev.  Quoting Debian
policy:

>>>
7.2. Binary Dependencies - `Depends', `Recommends', `Suggests', 
     `Enhances', `Pre-Depends'
----------------------------------------------------------------------------
[...]
     The meaning of the five dependency fields is as follows:

     `Depends'
[...]
          The `Depends' field should be used if the depended-on
	  package is required for the depending package to provide a
	  significant amount of functionality.
<<<

with "significant amount of functionality" being the key phrase.  So
Depends: is a weak dependency, not an absolute one (whether this is
good or nor is debatable...).

However, it seems you are right: whenever _some_ ghc package needs
util, it will implicitly depend on libreadline being installed, even
if readline is never really linked to.

So, what can be done?

The hot-fix is to install libreadline4-dev.

I _could_ make readline a hard dependency of ghc, but this is somehow
not satisfactory.  I'd rather like readline to be out-factored to its
own package (I know, this would break other Haskell programs, but it's
arguably easy-to-fix breakage...).

Comments?


Cheers,
Michael