module Logic.Language where

-- Formal language (/grammar/production system/whatever)
class (Eq symbol, Show symbol) => Language symbol where
  -- If Haskell had dependent types this could be generalized.
  -- For now the languages I want to make use at most up to infer3.
  infer0 :: [[symbol]]
  infer1 :: [[symbol] -> [[symbol]]]
  infer2 :: [[symbol] -> [symbol] -> [[symbol]]]
  infer3 :: [[symbol] -> [symbol] -> [symbol] -> [[symbol]]]

-- Convenience newtype so strings are less ugly
newtype Seq symbol = Seq [symbol]
instance Show a => Show (Seq a) where
  show (Seq xs) = concat $ map show xs