Re: [Haskell-cafe] How to direct cabal to use an alternative ghc version, ala stack?

If I had to guess, I'd say there's a directory structure like: /project /foo /bar /baz And stack found all the packages in those subdirs. It just happened to be that those were the exact ones that were add-source'd. But this is just a guess, of course. Erik On 3 September 2015 at 15:25, Michael Snoyman wrote:

I'm glad it worked, but I don't think it's doing what you think it's doing. stack intentionally ignores cabal sandbox settings and the like so that the tools don't step on each others' toes. I'm not sure what --add-source you were using, but it's very unlikely that stack picked it up.

I am now quite curious what the problem was and how stack ended up just working for this.

On Thu, Sep 3, 2015 at 3:32 PM, David Banas wrote:

...

Thanks to all, whom replied.

I found that a simple “stack install …” worked perfectly, as an alternative to “cabal install ...". Stack seems to have honored all the “cabal …” things I did in setting up my sandbox, including all my “cabal sandbox —add-source …” commands (5 in all). And, of course, it used the back-rev’d version of ghc I configured it (i.e. - stack) for.

That is SO neat that I can’t understand why it’s not a featured item in the Stack documentation. Thanks, Stack crew!

-db

On Sep 2, 2015, at 8:59 PM, Michael Snoyman wrote:

On Thu, Sep 3, 2015 at 3:37 AM, David Banas wrote:

...

Hi all,

How do I direct cabal to use an alternative (i.e. - not my system’s default) version of ghc, which I’ve installed, via stack?

I tried this:

stack exec cabal install ...

but got this:

cabal: Use of GHC's environment variable GHC_PACKAGE_PATH is incompatible with Cabal. Use the flag --package-db to specify a package database (it can be used multiple times).

Thanks, -db

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We have a flag to working better with cabal, you can try:

stack exec --no-ghc-package-path -- cabal install

I'm under the impression that there are changes planned to cabal (possibly already implemented but not released) that will allow it to function nicely with the GHC_PACKAGE_PATH environment variable, but I'm uncertain if that's true.

Michael

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