[Haskell-cafe] cabal-install profiling libraries

[Daniel Fischer]

On Friday 20 August 2010 15:20:41, Johannes Waldmann wrote:
> Here's another instance of the machine (*) telling me what to do,
> instead of doing it (or am I missing something):
>
> I have a large set of cabal packages installed with ghc.
> Then suddenly I need some package Foo with profiling.
> So I switch to library-profiling: True  in  my .cabal/config,
> and then "cabal install Foo" -  failing with the message:
>
>  Perhaps you haven't installed the profiling libraries for package `Bar'
>
> for some package Bar that Foo depends upon. - Dear Cabal: Yes!
> I know that I haven't installed them! I want you to install them for me!
> But it isn't listening ...

The problem is that otherpackages may depend on them too, so when cabal 
automatically reinstalls, those can break.
I don't think GHC can register a profiling version of the package and leave 
the vanilla package in peace, so then cabal can't just build the profiling 
lib and keep the old vanilla either.

>
> (*) "machine" = everything in that metal box that was so expensive
> and has a lot of cables coming out, and ventilators running.
>
>
> Of course you know that I have the highest respect for the work
> of the cabal authors. I'm just suggesting that the above feature
> (auto-re-install dependencies) would be helpful. Perhaps it's already
> there? If not - would it be hard to specify? To build? Or would it have
> bad consequences?
>
> Is it "cabal upgrade --reinstall"? But that was deprecated?

cabal install --reinstall

> Here I really want "reinstall with exactly the same versions".
> Is it the problem that their sources may have vanished, meanwhile?
> Could it be solved by having "cabal install" storing a copy of
> the source package that it used?

cabal keeps the tarballs of the packages, so that's not a problem.