[Haskell-cafe] Norvig's Sudoku Solver in Haskell

[manu]

> From: Malte Milatz <malte at gmx-topmail.de>
> Subject: Re: [Haskell-cafe] Norvig's Sudoku Solver in Haskell
>
> Your program was wrapped by your mail client, so you may want to  
> hpaste
> your program for easier digestion.
>

here it is : http://hpaste.org/2452

>
> Your profiling output suggests that much time is consumed by the  
> lookup
> function. Since you're using (fromJust . lookup) everywhere anyway, a
> data structure not envolving the Maybe type is probably a more succint
> choice. And why bother with characters and strings?
>

no rationale except that's what the original Python script did use




>>  newV2 <- case length newCell of
>>              0 -> Nothing
>>              1 -> do let peersOfS =  [ s' | s' <- lookup s peers ]
>>                      res <- foldM  eliminate newV (zip peersOfS  
>> (cycle newCell))
>>                      return res
>>               _ -> return newV
>
> The use of “length” here is not an actual performance problem, but
> unnecessary. Simply write: case newCell of []  -> ...
>                               [_] -> ...
>                               _   -> ...
>
> The same is valid for your other use of length.
>
> Malte

I see, thanks !

E.D