RosettaCodeData/Task/Visualize-a-tree/Racket/visualize-a-tree.rkt

14 lines
511 B
Racket

#lang racket/base
(define (visualize t0)
(let loop ([t t0] [last? #t] [indent '()])
(define (I mid last) (cond [(eq? t t0) ""] [last? mid] [else last]))
(for-each display (reverse indent))
(unless (eq? t t0) (printf "|\n"))
(for-each display (reverse indent))
(printf "~a~a\n" (I "\\-" "+-") (car t))
(for ([s (cdr t)] [n (in-range (- (length t) 2) -1 -1)])
(loop s (zero? n) (cons (I " " "| ") indent)))))
(visualize '(1 (2 (3 (4) (5) (6 (7))) (8 (9)) (10)) (11 (12) (13))))