[Haskell-cafe] Cabal in ghc 6.4.2

allan a.d.clark at ed.ac.uk
Sun Jul 30 10:47:09 EDT 2006

> The Text.ParserCombinators.Parsec modules are in the parsec module.
>> build-depends:  base
> Add parsec here:
> build-depends:  base, parsec
> The reason it works when you run it without -hide-all-packages is that
> by default for convenience all packages are 'exposed'. That is they can
> be used without explicitly having to specify them. However it was felt
> that for distributing software, which is one of the main purposes of
> Cabal, one should be fully explicit about the dependencies so that users
> compiling on other machines know exactly what packages needed and don't
> end up with mysterious import errors.
Yip this sounds like a good policy to me too.

> Now it's true that Cabal could be a bit cleverer here and warn you
> before it even starts compiling that you have not specified all the
> right packages in the build-depends. At the moment however Cabal doesn't
> have a proper imports chaser so it can't do this.
> Duncan

Thanks very much for the response, however, adding "parsec" to the 
build-depends of the .cabal file now causes a slightly different error, 
and in fact this is the same error I get with my other project:
haskellprint$ ./Setup.hs  build
Preprocessing executables for haskellprint-0.1...
Building haskellprint-0.1...
Chasing modules from: Main.hs
Could not find module `Char':
  use -v to see a list of the files searched for
  (imported from ./Parser.hs)

so basically I was expecting 'Char' to be in the 'base' package, I guess 
this is wrong?

thanks again.

More information about the Haskell-Cafe mailing list