Top-level Evaluation Functions

    The functions  scheme_eval,  scheme_eval, etc., are top-level evaluation functions. Continuation invocations are confine to jumps within a top-level evaluation.

The functions  _scheme_eval,  _scheme_apply,  _scheme_apply_to_list provide the same functionality without starting a new top-level evaluation; these functions should only be used within new primitive procedures or syntax. Functions which call the non-top-level evaluation functions are special:

• Calls to non-top-level evaluation functions can return multiple times.
• Scheme values created by the function cannot be allocated on the C stack. Otherwise, if stack is copied into the heap and replace while the Scheme value is still accessible, the value or the the stack may be corrupted.