module REDef where

data R = Eps | Single Char | Cat R R | Or R R | Star R
    deriving (Eq, Show)

-- upTo n r = e + r + r^2 + ... + r^n
upTo :: Int -> R -> R
upTo n r | n > 0 = Eps `Or` Cat r (upTo (n-1) r)
         | n == 0 = Eps