[Haskell-beginners] cabal sandbox add-source installs but disappears

[Dimitri DeFigueiredo]

Hello all,

I am having "a bit" of an issue trying to use a source dependency with 
cabal. I have a very simple setup with only 2 packages:

~/code/haskell/package-tests/a-package
         a.cabal
         src/MainA.hs

and

~/code/haskell/package-tests/MinhaCommon
         MinhaCommon.cabal
         setup.hs
         src/MainCommon.hs

I have setup a sandbox for the MinhaCommon package and can build it. 
However, the first one (a-package) depends on the second (MinhaCommon). 
So, I also created a sandbox for it as such:

a-package>cabal sandbox init

and that seems to work fine...

Writing a default package environment file to
/Users/dimitri/code/haskell/package-tests/a-package/cabal.sandbox.config
Creating a new sandbox at
/Users/dimitri/code/haskell/package-tests/a-package/.cabal-sandbox

I then add the source package and install...

a-package>cabal sandbox add-source '../MinhaCommon/'
a-package>cabal install --only-dep
Resolving dependencies...
Notice: installing into a sandbox located at
/Users/dimitri/code/haskell/package-tests/a-package/.cabal-sandbox
Configuring MinhaCommon-0.7.0...
Building MinhaCommon-0.7.0...
Installed MinhaCommon-0.7.0
Updating documentation index
/Users/dimitri/code/haskell/package-tests/a-package/.cabal-sandbox/share/doc/x86_64-osx-ghc-7.10.2/index.html

Here's the snag!

a-package>cabal configure
Resolving dependencies...
Configuring a-0.1.0...
cabal: At least the following dependencies are missing:
MinhaCommon ==0.7.0

WTF!? I just installed that!


The cabal file for package 'a' just includes the MinhaCommon package 
thru the build-depends section
(http://pastebin.com/Wpz5845k)
------------------------------------------------
name:                a
version:             0.1.0
build-type:          Simple
cabal-version:       >=1.20
----------------------------------------------
executable a
   main-is:          MainA.hs
   hs-source-dirs:   ./src

   build-depends:      base                  >= 4.4
                     , unordered-containers
                     , unix
                     , process
                     , stm
                     , MinhaCommon           == 0.7.0

   default-language:    Haskell2010
------------------------------------------------

Any pointers on how to get this to build are much appreciated.

Thanks,

Dimitri