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;;;; Structure and Interpretation of Computer Programs
;;;; Chapter 2 Section 1 Introduction to Data Abstraction
;;; Exercise 2.04 cons, car, and cdr as closures
(define (cons x y)
(lambda (m) (m x y)))
(define (car z)
(z (lambda (p q) p)))
;; This idea is similarly presented in "The Seasoned Schemer" (maybe Felleisen
;; and Friedman borrow it from SICP?). Even having seen it before, it's still
;; mind-blowing. Appropriate definition of cdr...
(define (cdr z)
(z (lambda (p q) q)))