<div dir="ltr"><div>In your definition for data set, I'm concerned about the call to read-json. The documentation doesn't say if it raises an exception on malformed json, but a quick test shows that it does indeed raise an exn:fail:read exception for bad input. So your call to read-json should include an exception handler to make sure your input port gets closed when you're done. Perhaps it should be something like: (define data-set (let* ( ;; Turn url into a net/url-struct so you can allow a different search query as well as other customizations ;; easily. [api-url (string->url "<a href="http://gdata.youtube.com/feeds/api/videos/?alt=json&v=2&category=Movies&q=Inception">http://gdata.youtube.com/feeds/api/videos/?alt=json&v=2&category=Movies&q=Inception</a>")] ;; figure out how to use call/input url [in (get-pure-port api-url #:redirections 2)] [json-blob (with-handlers ([exn:fail:read? (lambda (e) #f)]) (read-json in))]) (close-input-port in) json-blob)) </div>So close-input-port gets called either way, but if the returned json is malformed, json-blob will be set to #f, so data-set will be set to #f. #f just needs to be in tail-position for that lambda, you could do whatever you want before it to inspect the exception or figure out how to stop your program from continuing. </div><div class="gmail_extra"> <div class="gmail_quote">On Mon, May 13, 2013 at 5:45 AM, Cody Goodman <<a href="mailto:codygman.consulting@gmail.com" target="_blank">codygman.consulting@gmail.com</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Hello, can anyone offer an idiom/thinking process/approach critique on my code below? I'm new to racket and trying to program in racket, not program python in racket syntax ;) #lang racket (require json) (require net/url) (define data-set (let* ( ;; Turn url into a net/url-struct so you can allow a different search query as well as other customizations ;; easily. [api-url (string->url "<a href="http://gdata.youtube.com/feeds/api/videos/?alt=json&v=2&category=Movies&q=Inception" target="_blank">http://gdata.youtube.com/feeds/api/videos/?alt=json&v=2&category=Movies&q=Inception</a>")] ;; figure out how to use call/input url [in (get-pure-port api-url #:redirections 2)] [json-blob (read-json in)]) (close-input-port in) json-blob)) (struct movie (title price link)) (define movies (hash-ref (hash-ref data-set 'feed) 'entry)) (define (make-movie movie-result) (let* ( [title (hash-ref (hash-ref movie-result 'title) '$t)] [price (with-handlers ([exn:fail? (lambda (exn) 0)]) (hash-ref (car (hash-ref (hash-ref movie-result 'media$group) 'media$price)) 'price))] [link (hash-ref (car (hash-ref movie-result 'link)) 'href)] [movie-to-return (movie title price link)]) movie-to-return)) (define (make-movie-listing movie) (list (movie-title movie) (movie-price movie) (movie-link movie))) (define (show-all-movie-listings) (map make-movie-listing (map make-movie movies))) (define (get-relevant-movie-listings movie) ;; TODO: Figure out how to pass paramters into a function with map. Maybe lambda? (cond [(string=? (movie-title movie) "Inception") movie])) ;; TODO: Make this into a function after figuring out how to pass parameters into a function with map. (define find-movie (car(map get-relevant-movie-listings (map make-movie movies)))) (define inception-movie find-movie) (movie-title inception-movie) </div> ____________________ Racket Users list: <a href="http://lists.racket-lang.org/users" target="_blank">http://lists.racket-lang.org/users</a> </blockquote></div> </div>