On Mon, Jul 26, 2010 at 08:13, ka <sancha...@gmail.com> wrote: >> For the program, I know that when processing a character, I do not >> need the previous result. All I need is the current character, and I >> can return a function that acts on the result. I'm not sure if this is >> simple to implement in a functional way. > > Actually my understanding says that you need the whole list as this > cannot be implemented as lazy ? (you might have any number of > backspaces ahead so you need all the result) > > See also: http://kotka.de/blog/2009/11/Stopping%20Times%20and%20Laziness.html
Yes, you're quite correct. I reformulated the assignment a bit. ;-) Strings are not lazy in Java & Clojure. However, the originally proposed solution is only half-lazy. It's lazy on the input. The ouput is always fully realized. Consider also that a StringBuffer of N chars uses far less heap than a vector of N Characters due to per-object overheads. So, in the end, a fully eager solution based on strings might be preferable to a half-lazy solution. That would depend on the problem size. That said, don't use my code. It's hideous. And by now, I'm sure there's a cleaner solution possible for my approach: The idea is to split the input string into a lazy list of substrings alternating between strings containing no "<" and strings composed soley of "<". We then consume these strings 2 at a time, using the length of the second to modify the first before passing it through. The concatenation of the resulting lazy sequence of strings is the solution. // Ben -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
