Platform policy question: API compatability in minor releases

Heinrich Apfelmus apfelmus at
Tue May 12 07:08:29 EDT 2009

Duncan Coutts wrote:
> Heinrich Apfelmus wrote:
>> Can the Haskell Platform be uninstalled / upgraded seamlessly?
> This depends on the packaging for each OS.
> The Windows installer will install a new ghc and set of packages without
> disturbing existing installations. The source based installer will do
> the same (though it has no builtin uninstall facility). Not sure yet
> about OSX.
>> I think it's a key technical requirement for shorter release cycles that
>> installing a new release does not break due to any old ones that were
>> installed previously.
> It is possible in principle though many distro packaging systems only
> allow one version of a package at once.

Ah, what I meant is that the following scenario:

   1) User installs Haskell Platform 1.0
   2) New release of the Haskell Platform, version 1.1
   3) User downloads the new release and installs it

   4) User is no longer able to compile or run
      his Haskell programs because of some
      artifact from HP 1.0 that interferes with the
      new install of HP 1.1.

      For instance, what about his previous Hackage

      Both HP 1.0 and HP 1.1 work fine in isolation.

   5) User expresses his emotions in various ways,
      like breaking in tears on the #haskell channel,
      writing furious blog posts or divorcing Haskell

So, having only one release installed is not a problem, and the Linux
package managers in general are unlikely to create the mess required for 4).

But I bet that 4) is going to happen for the Windows and OS X
installers. I think it would be counterproductive to the goals of the HP
if people don't upgrade because they don't want to risk breaking their
working Haskell environment.



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