Since we're unable to deal with seq'ing over function values, comment out the Eval instance for (->)
%*********************************************************
\begin{code}
-instance Eval (a -> b)
+-- The current implementation of seq# cannot handle function types,
+-- so we leave this instance out rather than make false promises.
+--
+-- instance Eval (a -> b)
instance Show (a -> b) where
showsPrec p f = showString "<<function>>"