What happens in create-bst-word, when the word to inserted is the same as (node-word bst) ?
/Jens Axel 2014-08-05 21:56 GMT+02:00 Daniel Bastos <dbas...@toledo.com>: > After studying chapter 14 of HtDP, I decided to try putting strings into a > BST. The code below works with a few strings. I have a file with 22064 > strings --- one per line. Up until 1471 words, it works. With 1472 it yields > a contract violation. > >> (length (read-words)) > 22064 > >> (create-bst-word-from-list (take (read-words) 1471)) > #<node> > >> (create-bst-word-from-list (take (read-words) 1472)) > node-word: contract violation > expected: node? > given: #<void> > context...: > /home/dbastos/public_html/rkt/functions.rkt:974:0: create-bst-word > /home/dbastos/public_html/rkt/functions.rkt:987:0: > create-bst-word-from-list > /home/dbastos/public_html/rkt/functions.rkt:987:0: > create-bst-word-from-list > /home/dbastos/public_html/rkt/functions.rkt:987:0: > create-bst-word-from-list > /home/dbastos/public_html/rkt/functions.rkt:987:0: > create-bst-word-from-list > /home/dbastos/public_html/rkt/functions.rkt:987:0: > create-bst-word-from-list > /home/dbastos/public_html/rkt/functions.rkt:987:0: > create-bst-word-from-list > /home/dbastos/public_html/rkt/functions.rkt:987:0: > create-bst-word-from-list > /home/dbastos/public_html/rkt/functions.rkt:987:0: > create-bst-word-from-list > /home/dbastos/public_html/rkt/functions.rkt:987:0: > create-bst-word-from-list > /home/dbastos/public_html/rkt/functions.rkt:987:0: > create-bst-word-from-list > /home/dbastos/public_html/rkt/functions.rkt:987:0: > create-bst-word-from-list > /home/dbastos/public_html/rkt/functions.rkt:987:0: > create-bst-word-from-list > /home/dbastos/public_html/rkt/functions.rkt:987:0: > create-bst-word-from-list > /home/dbastos/public_html/rkt/functions.rkt:987:0: > create-bst-word-from-list... > >> > > It seems node-word says I gave it a #<void>. Perhaps my list of words > contains a #<void>, but when I search for it, I do not find it. > >> (define ls (read-words)) >> (length ls) > 22064 >> (length (filter string? ls)) > 22064 >> (filter void? ls) > () > > So I'm perplexed. > > (define-struct node (word left right)) > > (define (create-bst-word bst str) > (cond > ((false? bst) > (make-node str false false)) > ((string<? str (node-word bst)) ;; insert at the left > (make-node (node-word bst) > (create-bst-word (node-left bst) str) > (node-right bst))) > ((string>? str (node-word bst)) ;; insert at the right > (make-node (node-word bst) > (node-left bst) > (create-bst-word (node-right bst) str))))) > > (define (create-bst-word-from-list ls) > (cond > ((empty? ls) false) > (else > (create-bst-word (create-bst-word-from-list (rest ls)) (first ls))))) > > (define (read-lines in) > (let* ((ln (read-line in))) > (cond > ((eof-object? ln) empty) > (else (cons ln (read-lines in)))))) > > (define (read-words) > (call-with-input-file "words" read-lines)) > > Thank you in advance for any information. > > ____________________ > Racket Users list: > http://lists.racket-lang.org/users > -- -- Jens Axel Søgaard ____________________ Racket Users list: http://lists.racket-lang.org/users
