rendered paste body(define (find-route orig dest G)
(local ((define (neighbours v G)
(cond
[(empty? G) (error 'neighbours (string-append (symbol->string v) " not in graph"))]
[else
(cond
[(symbol=? v (first (first G))) (second (first G))]
[else (neighbours v (rest G))])]))
(define (find-route-helper orig dest seen still-to-visit G)
(cond
[(and (empty? still-to-visit) (empty? (neighbours orig G))) false]
[(member dest seen) still-to-visit]
[(empty? (neighbours orig G))
(find-route-helper (first still-to-visit)
dest
seen
(second (rest still-to-visit)) G)]
[else (find-route-helper (first (neighbours orig G))
dest
(append (neighbours orig G) seen)
(append (list (first seen) (rest (neighbours orig G))) (list still-to-visit))
G)])))
(find-route-helper orig dest (list orig) empty G)))