[Haskell-beginners] Cabal: Upgrading to the latest version of library

Hello, Recently I had to update and install a newer version of a library. I executed the "cabal update", which downloads the latest package list. I had assumed that this command would also detect, build and install those libraries that have been upgraded. However this does not seem to be the case. I had to manually build the library and then use GHC's package manager do unregister the old version. My question is: how does one check for and upgrade the cabal libraries automatically? TIA, Hugo F.