cannot satisfy -package-id aeson-0.7.0.6-0eee69c20a6ac37a1ed3f0a5b9fd0229:
    aeson-0.7.0.6-0eee69c20a6ac37a1ed3f0a5b9fd0229 is unusable due to missing or recursive dependencies:
      attoparsec-0.11.3.4-f914e42919eac942ba5e6ee1ac04790f hashable-1.2.2.0-0c662c50ab8227a1eba932300663cbb4 scientific-0.3.2.1-c6ed5dbaa429fdd1469cd78
c439876c9 unordered-containers-0.2.5.0-5e0d64c28dcd6c2a28787a3811ece1ea
    (use -v for more information)

% cabal sandbox hc-pkg list  -- -v | grep -e aeson -e hashable -e attoparsec -e scientific -e unordered-containers
Timestamp 2014-10-03 08:20:16.482925464 UTC for /home/feuerbach/work/.cabal-sandbox/i386-linux-ghc-7.8.3-packages.conf.d/package.cache
Timestamp 2014-10-03 08:20:16 UTC for /home/feuerbach/work/.cabal-sandbox/i386-linux-ghc-7.8.3-packages.conf.d (older than cache)
Timestamp 2014-09-12 20:31:35.03885547 UTC for /opt/ghc783/lib/ghc-7.8.3/package.conf.d/package.cache
Timestamp 2014-09-12 20:31:34 UTC for /opt/ghc783/lib/ghc-7.8.3/package.conf.d (older than cache)
    aeson-0.7.0.6 (aeson-0.7.0.6-0eee69c20a6ac37a1ed3f0a5b9fd0229)
    attoparsec-0.11.3.4 (attoparsec-0.11.3.4-f914e42919eac942ba5e6ee1ac04790f)
    hashable-1.2.2.0 (hashable-1.2.2.0-0c662c50ab8227a1eba932300663cbb4)
    scientific-0.3.2.1 (scientific-0.3.2.1-c6ed5dbaa429fdd1469cd78c439876c9)
    unordered-containers-0.2.5.0 (unordered-containers-0.2.5.0-5e0d64c28dcd6c2a28787a3811ece1ea)