#lang racket

(define prefix-list-r
      (lambda (op L-accum L-todo)
        (if (null? L-todo)
            L-accum

            ; add the next element to the end and recurse
            (prefix-list-r op
                ; new L-accum
                (append L_accum
                  (list (op (last L-accum) (first L-todo))))
                (rest L-todo))
            )
        )
      )

(define prefix-list
  (lambda (op L)
    (prefix-list-r op (list (first L)) (rest L))))