- scheme-report-environment version #!optional mutableprocedure
- null-environment version #!optional mutableprocedure
Version must be either the exact integer 4 or 5, corresponding to the respective revisions of the Scheme report (the Revised^N Report on Scheme). Scheme-report-environment returns a specifier for an environment that is empty except for all bindings defined in this report that are either required or both optional and supported by the implementation. Null-environment returns a specifier for an environment that is empty except for the (syntactic) bindings for all syntactic keywords defined in this report that are either required or both optional and supported by the implementation.
The environments specified by scheme-report-environment and null-environment are immutable by default. In CHICKEN, as an extension to R5RS, an extra mutable argument can be passed, which makes the environments mutable when non-#f. Mutability means new top-level definitions are accepted and the values of existing top-level bindings can be mutated.