Thanks Ben.
Both A and B (mentioned in Simon's reply) are good alternatives as long as existing Hoopl users are NOT forced to upgrade when they upgrade Cable or Stackage. Otherwise, we will see more forks of Hoopl. Once Cable and Stackage gain the multi-version capability, A and B can be merged back to Hoopl as a major release.
In my experience, Hoopl based optimizations/program analyses tend to use a lot of memory, but they are also easy to verify. So it's still a useful tool in some special use cases. If the performance of Hoopl can be improved, it will certainly be more useful.
Cheers,
Ning