{
{-# LANGUAGE BangPatterns #-}
module Eval where

import Control.Monad.Error
}

itf I
  visit v
    syn x :: Int
    
data D
  con C
    y :: Int

{
t = sem t : I monad IO
      visit v
        clause c
          match D.C@m = D_C 3
          lhs.x = m.y
}