WG1 Scheme implementations SHOULD provide a REPL.
At startup, a REPL MUST import the core module and MAY import an implementation-defined list of other modules. Implementations SHOULD allow this list to be changed in advance.
A REPL MUST allow other modules to be imported using the same syntax as is used when one module imports another. Imports may be performed at any time during the life of the REPL. It is undefined how many times an imported module is instantiated.
Definitions and expressions to be evaluated MAY be intermixed freely. Identifiers and syntax keywords MAY be redefined, subject to the following rules:
A REPL MUST provide the syntax (include filename), which causes the declarations and expressions in filename to be processed exactly as if they had been input directly to the REPL.
A REPL MAY provide a means of loading modules or include files that have been compiled by a compiler associated with the implementation.