Find all possible redexes of a given lambda term

find-redexes.rkt

#lang racket

(define (find-redexes e)
  (match e
    [`(λ (,x) ,body) (find-redexes body)]
    [(? symbol? x) (void)]
    [`((λ (,x) ,body) ,arg)
     (begin
       (display "I found this redex!\n")
       (pretty-print e)
       (find-redexes body)
       (find-redexes arg))]
    [`(,e0 ,e1)
     (begin
       (find-redexes e0)
       (find-redexes e1))]))

(define example '((λ (x) ((λ (y) (x y)) x)) (λ (z) (z z))))