2.3 Repl module

provides functions that are strictly required for hscheme to actually be a lisp and also to be a programming language. These are mostly functions that do not evaluate their arguments. In traditional sense you would regard them as macros, but they are not macros as they mostly provide a way to modify the environment, or manipulate the evaluation process itself.

These functions corespond to their Scheme definitions, reading the R5RS specification and the source code should be enough to understand them.