libVersionFromInstalled :: Installed -> Maybe Version
libVersionFromInstalled (Library ghcPkgId) =
    case ghcPkgIdPackageIdentifier ghcPkgId of
       PackageIdentifier _ v -> Just v
libVersionFromInstalled :: Installed -> Maybe Version
libVersionFromInstalled (Library ghcPkgId) =
    case ghcPkgIdPackageIdentifier ghcPkgId of
       PackageIdentifier _ v -> Just v
libVersionFromInstalled (Library ghcPkgId) =
    case ghcPkgIdPackageIdentifier ghcPkgId of
       PackageIdentifier _ v -> Just v