butlast.rkt

#lang racket
(define es (list 1 2 3))

(define base
  (lambda (k)
    (lambda (es)
      '())))

(define step
  (lambda (k)
    (lambda (es)
      (cons (first es)
            (k (rest es))))))

(define butlast
  (lambda (es)
    ((if (empty? (rest es))
        (base identity)
        (step butlast)) es)))

(butlast es) ;; => '(1 2)