package EqFunction() where

import Enum
import List

--@ \subsubsection{EqFunction}
--@
--@ \index{EqFunction@\te{EqFunction} (package)|textbf}
--@ Functions can be compared for equality if the domain
--@ can be enumerated and the range can be compared for equality.
--@ \begin{libverbatim}
--@ instance Eq #(a -> b)
--@   provisos (Bits#(a, sa), Bounded#(a), Eq#(b));
--@ \end{libverbatim}
instance (Bits a sa, Bounded a, Eq b) => Eq (a -> b)
  where
    (==) f g  =  foldr (\ x r -> f x == g x && r) True enumAll
    (/=) f g  =  not (f == g)

--@ The ability to compare functions for equality can be useful
--@ for compile time verification of properties of the {\blue} code.