assignment3.hs

{-
	Assignment3 
	Written by: Michael Schwarz Stuart Woodbury Neh Patel and Matthew Henry

        see Alternative.hs
-}
import System.Environment
import System.IO
import Data.List
import Control.Applicative
import Data.List.Split
import Alternative        --all the functions are in Alternative

main :: IO ()
main = 
     do
	args <- getArgs      --supposedly reads two arguments. error if user doesn't                           
        let students = read(head args) :: Int      
            grpsize = read(head $tail args) :: Int

        if checkmod students grpsize
           then
               do
               let a = combinations (students `div` grpsize) [1..students] --gets combinations of maximum group size
                   b = getUnique a  --gets the combinations of maximum group size where no one works together more than once 
               if (length b) < 8 * (students `div` grpsize) --fail
                  then putStrLn "it is impossible to group all the students in maximum group sizes for every assignment"
                  else
                      mapM_ putStrLn b --prints out the unique combinations
           else
               do
                 putStrLn "Cannot pair up " ++ (show students) ++ " students into groups of " ++ show(grpsize) ++ " across eight assignments"