Unregistering a package

[Simon Marlow]

On 09 February 2005 13:32, Peter Simons wrote:

> I have an interesting problem. There are two versions of the
> HsDNS package installed right now:
> 
>  $ ghc-pkg list
>  | /usr/local/ghc-current/lib/ghc-6.5/package.conf:
>  |     rts-1.0, [...]  (hsdns-2005-02-04),
>  |     hsdns-2005-02-08
> 
> Now how can I unregister them? I have tried everything I
> could think of, but no luck:
> 
>  $ ghc-pkg unregister hsdns
>  | ghc-pkg: package hsdns matches multiple packages:
>  |   hsdns-2005-02-04, hsdns-2005-02-08
> 
>  $ ghc-pkg unregister hsdns-2005-02-08
>  | ghc-pkg: cannot parse 'hsdns-2005-02-08' as a package identifier
> 
> Can someone give me a pointer how to remedy this situation?

The problem is not really that "hsdns-2005-02-08" isn't a legal package
identifier, actually it is an ambiguous package identifier.  I suggest
you remove that package by hand from the package.conf file, and instead
use "hsdns-2005.02.08".

The general syntax of package ids is:

   pkgid ::= pkg ('-' version)?
   pkg ::= (alphanum|'-')+
   version ::= (digit+) ('.' digit+)* ('-' alphanum+)*

This syntax means that package ids which have numeric component(s) at
the end and no '.' will be ambiguous.

I've added a test to ghc-pkg to prevent you from registering a package
with a problematic package id for now.  Perhaps we should change the
syntax of package ids though?

Cheers,
	Simon