[plt-scheme] Re: Help requested for HtDP Exercise 16.3.4 Challenge Part 2

Here are 2 important points i use when problem is complex.

1. Remember what a function produces , without going into the
   details how it produces
2. How to combine what we have with what function produces



Here are the some clues , i hope i don't confuse you more .



;;find? : dir symbol -> list-of-paths or false
(define (find? a-dir a-sym) ..)

;;1. If file is found in a current directory(find-in-files?) what to do we
;;   have and what to do with other dirs in this current dir
;;          a. (dir-name a-dir)
;;          b. (find-in-dirs? (dir-dirs a-dir) a-sym) produces what?
(false or list-of-paths)

;;Hint:         How will you combine the two and
;;                if b is a list-of-paths then we need to
;;                insert or prefix "what" to each element in list-of-paths

;;2. If file is not found in current dir then
;;       a. Do we search for dirs in current dir if so which function to use
;;       b. What that function return and what is needed to be inserted into
;;          it


;;find-in-dirs? : list-of-dirs symbol -> list-of-paths or false
(define (find-in-dirs? alods a-sym) ..)

;;1.  alods is empty ...

;;2.  (find? (first alods) a-sym)  produces what ?

;;       a. if 2 is false  what to do
;;       b. else we have (find? (first alods) a-sym)

;;       Now for b. we have list-of-paths and we also have
;;       a list-of-paths from (find-in-dirs? (rest alods) a-sym)
;;       Only thing is needed to combine them
;;       remember find-in-dirs? returns what?


;;find-in-files?: list-of-files a-sym -> boolean
(define (find-in-files? alofs a-sym) ..)



;;insert-or-prefix-funcion :

Veer

On Sun, May 11, 2008 at 10:29 AM, dave yrueta <dyrueta at gmail.com> wrote:
> Hi Matthias --
>
>
>  >BTW, I didn't see any check-expects and test-examples but this could
>  > be due to your formatting.
>
>  Did not run check-expects (forgot that existed) but do have test
>  examples with desired outcomes under each function purpose statement.
>  Also contrasted expected outcomes with actual outcomes at the end of
>  the post.
>
>
>  >You might be better off posting a url to a
>  > solution.
>
>  Here it is --
>
>  http://docs.google.com/Doc?id=dhdqh3jf_10g9gt37ds
>
>  I apologize for the length of the post.  I have a hard time keeping it
>  brief while justifying each move with respect to the design recipe.
>
>
>
>
>
>
>
>  On May 10, 5:47 pm, Matthias Felleisen <matth... at ccs.neu.edu> wrote:
>  > On May 10, 2008, at 7:50 PM, dave yrueta wrote:
>  >
>  >
>  >
>  > > I've found it difficult to isolate the problem within a single
>  > > function since they are all interrelated.
>  >
>  > Sorry no time to look thru details BUT when you have mut rec specs of
>  > data, you get mut rec functions to process them. And yes, in that
>  > case it's nearly impossible to write independent tests (and find
>  > problems).
>  >
>  > ;; ---
>  >
>  > BTW, I didn't see any check-expects and test-examples but this could
>  > be due to your formatting. You might be better off posting a url to a
>  > solution. My Mail client scrambles your posting.
>  >
>  > -- Matthias
>  >
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