showMatrix m m' =  unlines [  unwords (compareRow r r') | (r,r') <-  zip m m' ]
showMatrix m m' =  unlines [  unwords (compareRow r r') | (r,r') <-  zip m m' ]
showMatrix m m' =  unlines [  unwords (compareRow r r') | (r,r') <-  zip m m' ]