In This Exercise We Implement The Method Just Described For Interpreting Internaldef 661595

In this exercise we implement the method just described for interpreting internaldefinitions. We assume that the evaluator supports let.

a. Change lookup-variable-value to signal an error if the value it finds is thesymbol *unassigned*.

b. Write a procedure scan-out-defines that takes a procedure body and returns an equivalentone that has no internal definitions, by making the transformation described above.

c. Install scan-out-defines in the interpreter, either in make-procedure or inprocedure-body. Which place is better? Why?