[plt-scheme] HTDP 16.3.4

On Sep 22, 2006, at 5:28 PM, wooks . wrote:

>
> I am looking at the last part of the section marked Challenge which  
> requires a function
>
> ;;func-producing-list-of-lists: symbol directory-structure ->  
> [[symbol]]
> ;;produces a list of all the paths to files of the specified name  
> in the directory structure.

Where is the definition of [[symbol]]? Where is the definition of  
"directory-structure"?

Let's use the recipe. Presumably you have a template, one line in one  
function and three in the other keeping in mind that the function(s)  
really must return a list of paths. So

-- cases without cross or self-references: return a list, distinguish  
success from failure. done

-- cases with self- or cross-references: each recursive/cross call  
produces a list of paths to the "successes".  The answer is a  
combination of those partial results, plus the knowledge that these  
paths aren't complete. Since you figured out how to do one path, I  
bet that this part is a minor little step. It really is just a help  
function plus a line. 

-- Matthias





> I've  not been able to figure how to continue to generate paths  
> after finding the first one ..... well thats not quite true but I  
> presume removing entries from the directory so that the basic find  
> function selects a different path on each invocation isn't what is  
> sought for here.
>
>
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