readPGF :: FilePath -> IO PGF linearize :: PGF -> Language -> Tree -> String linearizeAllLang :: PGF -> Tree -> [(Language,String)] parse :: PGF -> Language -> Category -> String -> [Tree] parseAllLang :: PGF -> Category -> String -> [(Language,[Tree])] languages :: PGF -> [Language] categories :: PGF -> [CId] startCat :: PGF -> Category