The csp package

[Tags: lgpl, library]

Constraint satisfaction problem (CSP) solvers


[Skip to ReadMe]

Properties

Version1.0
Change logNone available
Dependenciesbase (>=3 && <5), containers, mtl (>=2), nondeterminism [details]
LicenseLGPL
AuthorAndrei Barbu <andrei@0xab.com>
MaintainerAndrei Barbu <andrei@0xab.com>
CategoryControl, AI, Constraints, Failure, Monads
Source repositoryhead: git clone git://github.com/abarbu/csp-haskell.git
UploadedWed Aug 14 08:53:46 UTC 2013 by AndreiBarbu
Downloads333 total (19 in last 30 days)
Votes
0 []
StatusDocs uploaded by user
Build status unknown [no reports yet]

Modules

[Index]

Downloads

Maintainers' corner

For package maintainers and hackage trustees

Readme for csp-1.0

CSP

A simple example which solves Sudoku puzzles, project Euler problem 96.

solveSudoku :: (Enum a, Eq a, Num a) => [[a]] -> [[a]]
solveSudoku puzzle = oneCSPSolution $ do
  dvs <- mapM (mapM (\a -> mkDV $ if a == 0 then [1 .. 9] else [a])) puzzle
  mapM_ assertRowConstraints dvs
  mapM_ assertRowConstraints $ transpose dvs
  sequence_ [assertSquareConstraints dvs x y | x <- [0,3,6], y <- [0,3,6]]
  return dvs
      where assertRowConstraints =  mapAllPairsM_ (constraint2 (/=))
            assertSquareConstraints dvs i j = 
                mapAllPairsM_ (constraint2 (/=)) [(dvs !! x) !! y | x <- [i..i+2], y <- [j..j+2]]

sudoku3 = [[0,0,0,0,0,0,9,0,7],
           [0,0,0,4,2,0,1,8,0],
           [0,0,0,7,0,5,0,2,6],
           [1,0,0,9,0,4,0,0,0],
           [0,5,0,0,0,0,0,4,0],
           [0,0,0,5,0,7,0,0,9],
           [9,2,0,1,0,8,0,0,0],
           [0,3,4,0,5,9,0,0,0],
           [5,0,7,0,0,0,0,0,0]]

mapAllPairsM_ :: Monad m => (a -> a -> m b) -> [a] -> m ()
mapAllPairsM_ f []     = return ()
mapAllPairsM_ f (_:[]) = return ()
mapAllPairsM_ f (a:l) = mapM_ (f a) l >> mapAllPairsM_ f l

solveSudoku sudoku3

Future