Question

I need to eliminate this Scheme lambda construction for my school assignment.

Any ideas how to accomplish this?

(define (foo x)
(letrec
  ((h 
    (lambda (y z)
      (cond
        ((null? y) 'undefined)
        ((null? (cdr y)) (car z))
        (else (h (cddr y) (cdr z)))
        ))))
  (h x x))
)

Answer 1

Well, you could replace the lambda expression in the letrec with an internal definition:

(define (foo x)
  (define (h y z)
    (cond
      ((null? y) 'undefined)
      ((null? (cdr y)) (car z))
      (else (h (cddr y) (cdr z)))))
  (h x x))

… Or you could extract the h procedure outside of foo, as a helper procedure. Either way the result would be the same.