{-
This Haskell program converts an md file to an hs by removing
everything that is not Haskell code.
* Lines between ““`haskell” and ““`” are copied.
* However, lines between ““`hs” and ““`” are not copied,
deliberately. This is to be able to control what to copy or not,
while still retaining syntax highlighting in both cases.
-}
import Data.Char
begin = ““`haskell”
end = ““`”
mdtohs :: [String] -> String
mdtohs [] = []
mdtohs (xs:xss)
| take (length begin) (dropWhile isSpace xs) == begin = copy (length (takeWhile isSpace xs)) xss
| otherwise = mdtohs xss
copy :: Int -> [String] -> String
copy i [] = []
copy i (xs:xss)
| take (length end) (dropWhile isSpace xs) == end = “\n” ++ mdtohs xss
| otherwise = drop i xs ++ “\n” ++ copy i xss
main :: IO()
main = interact(mdtohs.lines)