If you were to replace stream-cons with this function: (define (not-stream-cons x y) (printf "x ~s y ~s\n" x y) 'something-random)
would it make sense to you what happens? Robby On Thu, May 16, 2013 at 7:30 AM, Patrick Sweetman <sweetma...@woosh.co.nz>wrote: > I'm doing this problem: > > 6. Write a stream dan-then-dog, where the elements of the stream > alternate between the strings "dan.jpg" and "dog.jpg" (starting with > "dan.jpg"). More specically, dan-then-dog should be a thunk that when > called produces a pair of "dan.jpg" and a thunk that when called > produces a pair of "dog.jpg" and a thunk that when called... etc. Sample > solution: 4 lines. > > and I cannot for the life of me understand why the following code does > not produce a properly thunked stream. It evaluates the entries until it > runs out of memory > > (define dan "dan.jpg") > (define dog "dog.jpg") > > (define (dan-then-dog) > (define (H1 st0 b0) > (cond > [(= b0 1) (H1 (stream-cons dan st0) 0)] > [else (H1 (stream-cons dog st0) 1)] > ) > ) > (H1 empty-stream 1)) > > Can somebody please explain why my understanding of Racket streams is > faulty? > > Thanks, > Patrick Sweetman > ____________________ > Racket Users list: > http://lists.racket-lang.org/users >
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