\begin{code}
module TcRnTypes where

import IOEnv 

type TcM a = TcRn a
type TcRn a = TcRnIf TcGblEnv TcLclEnv a
type TcRnIf a b c = IOEnv (Env a b) c

data Env a b
data TcGblEnv
data TcLclEnv
\end{code}