Jakub,

It's certainly a hack, but one thing you can do is the following:

In your main package (the one which depends on your customization), simply set up a sandbox like this:

$ cd /home/me/my-package

$ cabal sandbox init

Then, in your custom mysql package, tell it to *share* a sandbox with "my-package" and then install it, like this:

$ cd /home/me/mysql-custom

$ cabal sandbox init --sandbox /home/me/my-package/.cabal-sandbox

$ cabal install

Now, back in "my-package", "cabal install --dependencies-only" will not re-download mysql. Make sure that your cabal config depends on the same package name and version that you have customized.

Hope this helps:

Elliot

From: "Miëtek Bak" <mietek@bak.io>
To: "Jakub Arnold" <darthdeus@gmail.com>
Cc: haskell-cafe@haskell.org
Sent: Saturday, February 7, 2015 9:50:08 PM
Subject: Re: [Haskell-cafe] Building with some dependencies pre-installed in a sandbox

It sounds like you’re looking for `cabal sandbox add-source`:
https://www.haskell.org/cabal/users-guide/installing-packages.html#developing-with-sandboxes

--
Miëtek

On 2015-02-08, at 02:33, Jakub Arnold <darthdeus@gmail.com> wrote:

> Hey guys, sorry for re-posting, but I feel that my original question is largely different from this one.
>
> I've managed to get my broken dependency to build (the mysql package), but unfortunately I had to manually change its source code to make this happen, (original post https://www.haskell.org/pipermail/haskell-cafe/2015-February/118064.html), but I do have the package installed locally (or in the sandbox of my app).
>
> The problem is that when I try to `cabal install` the whole application, it will re-download the `mysql` package from Hackage and try to build it again, instead of using the version I custom built and installed myself. Is it normal that cabal won't re-use the already existing packages, or did I somehow change it so that it won't recognize it?
>
> Also, is it possible to explicitly say where should cabal resolve some of its dependencies? Such as this case when one package is in a local path, and other should be built from hackage. I'm not really sure what the best approach is here.
>
> again sorry for posting twice in a row, but I just can't seem to find this information anywhere in the docs
>
> Thanks!
> _______________________________________________
> Haskell-Cafe mailing list
> Haskell-Cafe@haskell.org
> http://www.haskell.org/mailman/listinfo/haskell-cafe

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