Re: Haskell dependencies for custom cabal builds

[John Soo]

Hi there,

I did a little digging this morning and it seems like runhaskell is probably 
deprecated in favor of runghc. Do we expect anyone to be using hugs or jhc?  
Runghc also supports ghc flags. I still need to do some more research here but 
the Haskell configure phase deliberately unsets GHC_PACKAGE_PATH. I assume it 
does this because runhaskell supports many Haskell compilers. If custom cabal 
builds are rare, I would suspect that non-ghc builds are even rarer. Would it 
be possible to replace runhaskell with runghc? Or parameterize the command?

Thanks,

John

> On Feb 12, 2019, at 8:06 AM, Timothy Sample <address@hidden> wrote:
> 
> Hi John,
> 
> John Soo <address@hidden> writes:
> 
>> I’ll check out git-annex as a start. Custom Cabal builds would be a
>> nice feature to add to the haskell-build-system. Would it be
>> sufficient to add some extra argument to the build system?
> 
> At this point, I don’t know what the argument would do.  :)
> 
> The solution I came up with for git-annex only works for git-annex.  I
> had to carefully read the build code, and carve out certain parts so
> that they could run in different environments.  It is not something that
> could be enabled by an argument.
> 
> The only idea I have would be switching from using “runhaskell Setup.hs”
> to using the “cabal” executable.  Hopefully, Cabal would set up the GHC
> package database before running the custom code.  If it worked, it could
> be enabled by a build-system argument.  I’m definitely just guessing
> here, though.  If you wanted to test this, you could copy out code from
> “guix/build/haskell-build-system.scm” into custom phases in your
> package.  If it proves useful, we could adapt it into the build system.
> 
> So far, custom builds have been extremely rare, so these issues are not
> very well explored.
> 
> 
> -- Tim