This is the information about an installed package that
is communicated to the
ghc-pkg program in order to register
ghc-pkg now consumes this package format (as of version
6.4). This is specific to GHC at the moment.
.cabal file format is for describing a package that is not yet
installed. It has a lot of flexibility, like conditionals and dependency
ranges. As such, that format is not at all suitable for describing a package
that has already been built and installed. By the time we get to that stage,
we have resolved all conditionals and resolved dependency version
constraints to exact versions of dependent packages. So, this module defines
InstalledPackageInfo data structure that contains all the info we keep
about an installed package. There is a parser and pretty printer. The
textual format is rather simpler than the
.cabal format: there are no
sections, for example.