Breaks the loop between SimplEnv and MagicUFs, by telling SimplEnv all
it needs to know about MagicUFs (not much).

Also break the loop between SimplVar/SimplCase (which use
Simplify.simplExpr) and SimplExpr (which uses whatever
SimplVar/SimplCase cough up).

\begin{code}
interface SmplLoop where

import MagicUFs	    ( MagicUnfoldingFun )
import SimplEnv	    ( SimplEnv, InBinding(..), InExpr(..),
		      OutArg(..), OutExpr(..), OutType(..)
		    )
import Simplify	    ( simplExpr, simplBind )
import SimplMonad   ( SmplM(..) )

data MagicUnfoldingFun

simplExpr :: SimplEnv -> InExpr -> [OutArg] -> SmplM OutExpr
simplBind :: SimplEnv
	  -> InBinding
	  -> (SimplEnv -> SmplM OutExpr)
	  -> OutType
	  -> SmplM OutExpr
\end{code}