Evaluation Handler

 

        An evaluation handler is invoked by  eval,  read-eval-print-loop, and  load to evaluate Scheme expressions. An evaluation handler takes one argument, an S-expression to be evaluated, and returns the value of the expression (possibly multiple values; see section 2.26).

 
• (current-eval) returns the current evaluation handler.
• (current-eval f) sets the handler to f.

The default evaluation handler expands, compiles, and executes the input expression in the top-level environment.