import qualified Data.ByteString.Lazy as L
import qualified Data.ByteString.Char8 as C

chars =  ['A'..'Z'] ++ ['0'..'9']

colSizes :: [Int]
colSizes = [4, 4, 4, 3, 5, 1, 1, 3, 3, 3, 3, 3, 3, 10, 3, 1, 1, 1, 2, 3, 10]

buildRow = [replicate (colSizes !! x) (chars !! x) | x <- [0.. length colSizes - 1]]

chunkSize :: Int
chunkSize = 10000 -- lines

nl = C.singleton '\n'

rawBytes = C.intercalate nl . replicate chunkSize . C.pack . concat $ buildRow

lazyGenerator = L.cycle (L.fromStrict rawBytes)

main = L.putStr lazyGenerator