I've started looking more seriously into optimization (suggestions welcome). Don Stewart's blog post (http://cgi.cse.unsw.edu.au/~dons/blog/2008/05/16#fast) was quite useful, but it seems like there's a lot of arcane knowledge required to understand what's really happening in "core" code. Is there any better reference than Andrew Tolmach's paper "An External Representation for the GHC Core Language (2001)" http://citeseer.ist.psu.edu/tolmach01external.html?
As SPJ says, it is just a simple functional language (with unlifted and lifted types). The problem is probably more the syntax, than Core itself. There's a new paper about the core type system, http://research.microsoft.com/%7Esimonpj/papers/ext%2Df/ Otherwise, Andrew's paper is still a reasonable reference. I'd install ghc-core too, which cleans up the output somewhat, and helps with syntax highlighting. -- Don