[racket] Unreachable line reached

On 17/09/12 19:23, Danny Yoo wrote:
>
> Hi Paolo,
>
>
> When I look at the program more closely, I think the structure of the
> iteration might be improved with a "for" loop and the match library.
> I'm trying to avoid let loops these days just because they remind me
> too much of GOTO-sytle programming.  :)
>

Embarrassingly when I started using Scheme we didn't have for loops so I 
actually have never used them but I will take a look at their syntax.

>
> Here's my take on your snippet:
>
> ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
> (for ([line (in-lines in)])
>    (match (string-split line ",")
>      [(list path modtime-str md5-str)
>       (define modtime (string->number (string-trim modtime-str)))
>       (define md5 (string->bytes/utf-8 (string-trim md5-str)))

why not let for these?
I have always heard these kind of define's would be poor style. What's 
your take on this?

>       (cond
>         [(or (not path) (not modtime) (not md5))
>          (printf "[2] read-cache fails, unexpected line in cache file:
> ~a, ignoring.~n" line)]
>         [else
>          (hash-set! (*cache*) path (cons modtime md5))])]
>      [else
>       (printf "[1] read-cache fails, unexpected line in cache file: ~a,
> ignoring.~n" line)]))
> ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
>

Looks much better. Thanks.

>
> Good luck!
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-- 
PMatos