Development questions

How to traverse the environment?

The sequence of all declarations (logical ones such as Definition, but also non logical ones such as say Notation) is registered in a tree-like structure called the lib_stk. Each entry has a tag describing what kind of declaration it is, e.g. "CONSTANT" for Theorem/Definition/Axiom/Parameter/..., "VARIABLE" for Variable/Hypothesis/Let, "INDUCTIVE" for Inductive/CoInductive/Record/Variant, "NOTATION" for interpretation of notations, etc.

Independently, each kind of declaration generally comes with its own data structures or tables storing relevant information about this entry.

Back to the library stack, each entry there has a kernel name which is an identifier for fetching the information related to this entry in the appropriate table. For instance, with the kernel name of a "CONSTANT" you can get its body, type and other related informations by looking up the table of constants (function Global.lookup_constant). You can see examples of walking through the environment in the code for "Search" (Search.iter_declarations which itself relies on an iterator over module contents called Declaremods.iter_all_segments), or in the code for Print All (Printer.print_full_pure_context).