Cabal and Tool Dependencies

Isaac Jones ijones at
Mon Jul 11 01:25:17 EDT 2005

Brian Smith <brianlsmith at> writes:

> 1. How can I tell what tool dependencies a package has? For example, how can 
> I tell from a .cabal package that Happy 1.14 or later, or Alex 2.0 is 
> required for the package to build properly? I am making a simple tool that 
> uses .cabal files to build programs and I would like to be able to say "This 
> package requires Happy 1.14 to be installed" upon loading the .cabal file 
> (before the user runs "./Setup.hs build").

Neither of these is possible at this time.  I'd be happy to see a
proposal for such, but at the moment, Cabal only tracks dependencies
between libraries.

>  2. Is it possible to register binary (executable) packages? For example, I 
> would like to "register" Happy 1.15 with Cabal, somehow, so that Cabal knows 
> what version of Happy I have installed. This would eliminate the need for me 
> to use --with-happy, etc. when configuring.

If you only have one version of Happy installed, why would you need
--with-happy?  It just uses the one it finds in its path.



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