There's a rather extensive series of blog posts by Edward Yang, a GHC contributor, that cutely and obliquely describe the STG machine that gives semantics to ST

There's a rather extensive series of blog posts by Edward Yang, a GHC contributor, that cutely and obliquely describe the STG machine that gives semantics to STG code. Highly recommended for anyone who found this interesting! * http://blog.ezyang.com/2011/04/the-haskell-heap/ * http://blog.ezyang.com/2011/04/evaluation-on-the-haskell-heap/ * http://blog.ezyang.com/2011/04/io-evaluates-the-haskell-heap/ * http://blog.ezyang.com/2011/04/implementing-the-haskell-heap-in-python-v1/ * http://blog.ezyang.com/2011/04/functions-produce-the-haskell-heap/ * http://blog.ezyang.com/2011/04/how-the-grinch-stole-the-haskell-heap/ * http://blog.ezyang.com/2011/05/bindings-and-cafs-on-the-haskell-heap/ Also, C-- has updated from its spec as the author noted and... as far as I'm aware there aren't actually any updated specs or documentation. Perhaps a few papers? C-- was originally marketed as a new, designed intermediary language for compiling functional programs but it never quite took off as far as I understand. My understanding is that GHC is also moving toward using LLVM instead.