Example 2: a question-answering system → Haskell code

• import PGF
  
  main :: IO ()
  main = do pgf <- readPGF "Arithmetic.pgf"
            interact (unlines . map (translate pgf transfer) . lines)
  
  translate :: PGF -> (Tree->Tree) -> String -> String
  translate pgf transfer s =
    case parseAllLang pgf (startCat pgf) s of
       (lang,tree:_):_ -> linearize pgf lang (transfer tree)
       _ -> "NO PARSE"
  
  transfer :: Tree -> Tree
  --transfer = ...
  

• How to write the transfer function?