[Haskell-cafe] Code Review: Sudoku solver
robdockins at fastmail.fm
Wed Mar 22 16:24:12 EST 2006
On Mar 22, 2006, at 2:16 PM, David F. Place wrote:
> Hi All,
> I really appreciate all the help I received when I asked you to
> critique my PrefixMap module a few weeks ago. I think I am making
> good progress in correcting the "lisp" in my Haskell programming.
> I'll be very grateful to anyone who can take a glance at the
> attached short program and say if any unidiomatic usages pop out.
> sudoku :: Sudoku -> IO ()
> sudoku s = ((mapM_ putStrLn) . (check s) . (take 1) . solveSudoku) s
> check puzzle  = [showSudoku puzzle,"No solutions."]
> check puzzle [solution]
> | solution `solves` puzzle =
> ["Puzzle:",showSudoku puzzle,"Solution:",showSudoku
> | otherwise = ["Program Error. Incorrect Solution!"]
That '(check s) . (take 1)' bit looks a little odd to me. I would
simply have written 'check' to match like:
check puzzle  = <failure case>
check puzzle (solution : _ ) = <success case>
Also, I like to put off doing IO as long as possible, so I'd probably
have 'sodoku' return a String or [String] and move the putStr into
main. Its an easy way to make your code more reusable.
Also, your parser is pretty hackish (but I suspect you knew that
FYI, solveSudoku has a bug; if you enter an invalid puzzle it will
> It solves sudoku puzzles. (What pleasure do people get by doing
> these in their heads?!?)
I have no idea.
Speak softly and drive a Sherman tank.
Laugh hard; it's a long way to the bank.
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