module TRS where
    
import Data.List

data Term     = V String | F String [Term] deriving (Eq)
type Subst    = [(String, Term)]
type Rule     = (Term, Term)
type TRS      = [Rule]
type Position = [Int]

instance Show Term where
  show (V x)    = x
  show (F f ts) = f ++ "(" ++ intercalate "," [show t | t <- ts] ++ ")"

showRule :: Rule -> String
showRule (l, r) = show l ++ " -> " ++ show r

showTRS :: TRS -> String
showTRS trs = unlines [ showRule rule | rule <- trs ]