SICP Exercise 1.34

Exercise 1.34.  Suppose we define the procedure


(define (f g)
  (g 2))

Then we have


(f square)
4

(f (lambda (z) (* z (+ z 1))))
6


What happens if we (perversely) ask the interpreter to evaluate the combination (f f)? Explain.

SOLUTION

 The code and tests are here.

 Explanation:

 (f f) evaluates to (f 2) which in turn results in (2 2) where the first term 
is expected to be a procedure. So the evaluator doesn't accept it and gives an
error.

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