The Haskell Execution Model
The STG language has a clear operational model, as well as having a declarative lambda-calculus reading. The business of the code generator is to translate the STG program into
C--, and thence to machine code, but that is mere detail. From the STG program you should be able to understand:
- What functions are in the compiled program, and what their entry and return conventions are
- What heap objects are allocated, when, and what their layout is
GHC uses an eval/apply execution model, described in the paper How to make a fast curry: push/enter vs eval/apply. This paper is well worth reading if you are interested in this section.