[Haskell-cafe] Norvig's Sudoku Solver in Haskell
gale at sefer.org
Sun Aug 26 18:44:58 EDT 2007
>> Perhaps you would gain something if you used Data.Map.!
>> instead of your "lookup".
> I'm not sure I understand, do you mean I should have use a strict Map
> constructor ?
> like : Map !key !value ?
No, there is an operator in Data.Map called "!".
> how can it replace the lookup function ?
> import qualified Data.Map as M
> import Data.Map (!)
Then, instead of "lookup k m"
use "m ! k".
>> Other than that, I'm not
>> sure why your code runs slower than mine.
Malte Milatz wrote:
MM> The use of "length" here is not an actual
MM> performance problem...
Maybe not there, but I think Malte's suggestion might
actually improve performance if you do the same
thing a few lines further down, where you wrote:
> case length dPlaces of
By using Malte's idea there instead of length, you might
allow some calculations inside dPlaces to be lazily
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