module Formatter where
import Data.List

#if __GLASGOW_HASKELL__ <= 606
intercalate xs xss = concat (intersperse xs xss)
#endif

padWith :: a -> Int -> [a] -> [a]
padWith _ 0 l = l
padWith e n [] = replicate n e
-- http://hackage.haskell.org/trac/haskell-prime/wiki/RemoveNPlusK
-- Ugg... GHC could at least give a meaningful error message. ~ Matt 2011-08-27
padWith e n (h:t) =
	if n == 0 then error "padWith: list is already longer than the requested length"
	else h:(padWith e (n-1) t)

formatTable :: [[String]] -> String
formatTable cells =
	let columnWidths = map (\col -> maximum $ map length col)
		$ transpose cells in
	intercalate "\n" $
		map (\row ->
			let rowCells = zipWith (padWith ' ') columnWidths row in
			intercalate " " rowCells
		) cells