[gobolinux-devel] Enhance Compile to support Haskell Cabal builds

[Kevin Quick]

[Sorry Michael: my Spam filter ate your response, so I'm paraphrasing  
here]

Attached is an updated version of this patch against the SVN for  
Compile.  It utilized runhooks and SandboxInstall.  (Thanks due  
Michael Homer for the pointers)

On 10 Apr 2008, at 12:01 AM, quick at sparq.org wrote:
> Attached is a patch that will upgrade Compile/MakeRecipe to support  
> the Cabal
> build/library system (http://hackage.haskell.org/cabal) used for  
> Haskell
> (GHC).  This performs the build using the standard Haskell  
> methodology,
> registering the results to make it available for import in Haskell  
> programs.
> This also allows the easy reference to the Hackage library database  
> (http://
> hackage.haskell.org/) for Haskell.
>
> No management of the local Cabal database is made beyond the initial
> registration; specifically DisableProgram, SymlinkProgram, and  
> RemoveProgram
> will require corresponding manual modifications of the database  
> (e.g. via ghc-
> pkg), but installation and upgrades of packages are handled quite  
> nicely.

The issue here is that the Cabal database (visible via "$ ghc-pkg  
list") should be told when a new version is selected or a version is  
removed.  It supports hide/show (like Gobo's DisableProgram/ 
EnableProgram) and unregister (viz. RemoveProgram).  However, to  
effectively perform these, all of the various Gobo Scripts would need  
to look at the recipe type to detect a cabal recipe and then perform  
the needed actions.

It's generally possible to do this, although it represents  
significant modifications to the Scripts package; the current   
implementation pretty much matches the functionality provided by  
existing Haskell-implementing recipes, which use recipe_type of  
manifest and then just do the runhaskell Setup operations in the  
pre_install() hook manually.

If this package is going to move forward, then I would look into  
Scripts updates, but I didn't want to spend the work if this patch  
wasn't acceptable.

 > Where is this database stored?

The cabal/ghc-pkg environment supports 2: a system one and a user  
one.  I'm modifying the system one in the above patch.  The first  
line of "$ ghc-pkg list" shows where the database is located.

 > Is it necessary to use, or does it just provide extra  
functionality somehow?

It's pretty much necessary to resolve Haskell import statements.

-KQ

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