I'm trying to build the latest regex base, which is required for the other regex packages under ghc 6.7 It complains that it can't find Data.Sequence, because it's in a hidden module containers. I added containers to the cabal depends as can be seen in the grep below. And containers isn't hidden when I do ghc-pkg list. What gives? Still getting used to cabal... thomas. hartthoma@linuxpt:~/installs/regex-base-0.91>runghc Setup.hs build Preprocessing library regex-base-0.91... Building regex-base-0.91... Text/Regex/Base/RegexLike.hs:47:17: Could not find module `Data.Sequence': it is a member of package containers-0.1, which is hidden hartthoma@linuxpt:~/installs/regex-base-0.91>grep -i containers regex-base.cabal Build-Depends: base >= 2.0, mtl, containers hartthoma@linuxpt:~/installs/regex-base-0.91>ghc-pkg list /usr/local/lib/ghc-6.7.20070816/package.conf: Cabal-1.1.7, HUnit-1.1.1, QuickCheck-1.0.1, array-0.1, arrows-0.2.1, base-2.1, bytestring-0.1, cgi-3001.1.5, containers-0.1, directory-1.0, fgl-5.4.1, filepath-1.0, (ghc-6.7.20070816), haskell-src-1.0.1, haskell98-1.0, hpc-0.5, html-1.0.1, mtl-1.0.1, network-2.0.1, old-locale-1.0, old-time-1.0, packedstring-0.1, parallel-1.0, parsec-2.0, pretty-1.0, process-1.0, random-1.0, readline-1.0, regex-base-0.72, rts-1.0, stm-2.1, template-haskell-0.1, unix-2.0, xhtml-3000.0.2 --- This e-mail may contain confidential and/or privileged information. If you are not the intended recipient (or have received this e-mail in error) please notify the sender immediately and destroy this e-mail. Any unauthorized copying, disclosure or distribution of the material in this e-mail is strictly forbidden.