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
solution]
| 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
already).
FYI, solveSudoku has a bug; if you enter an invalid puzzle it will
return non-solutions.
It solves sudoku puzzles. (What pleasure do people get by doing
these in their heads?!?)
I have no idea.
Rob Dockins
Speak softly and drive a Sherman tank.
Laugh hard; it's a long way to the bank.
-- TMBG
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