Hi,
External Core is a feature of GHC that is lonely and unloved. External Core longs to have someone to look after it, tell it that it is a Truly Useful Feature, and keep it working.
Just for reference, Yhc.Core is deeply loved and very close to my heart. There are disadvantages to Yhc Core (no types, relatively new API, only works with Yhc accepted Haskell, can't compile Core files) and advantages (loved, simple, stable, used, pretty). I'm currently addressing the last disadvantage, so it will soon be able to compile Core files. Not wanting to "poach" GHC users, but for some projects Yhc.Core might be a better choice. I use it for my PhD, for DrHaskell, and a few other small projects and its really handy to have. I looked at GHC Core first, but didn't get very far, partly because it looks a bit ugly :) See http://haskell.org/haskellwiki/Yhc/API/Core Thanks Neil