No, that's not accurate. The final form of your Haskell program before it's compiled down to some assembly language (currently C-- or LLVM) is a graph reduction problem. The partially imperative part is the runtime system, which actually reduces the graph (= runs your program), but this is significantly more complicated than the sort of high level loop transformations you're talking about. Search "spineless tagless G-machine" for a (somewhat idealized) description of the core architecture of GHC.