module Coverage
	( 
		evaluate, domain, 
		num, values, 
		new_cov, fun, Coverages , Coverage
	)
	 where


class Coverages cov where
	new_cov :: [a] -> ( a -> b ) -> (cov a b) 
	evaluate :: (Eq a, Eq b) => cov a b -> a -> Maybe b
	domain :: cov a b -> [a] 	 
	num :: cov a b-> Int
	values :: cov a b -> [b]
	fun :: (cov a b) -> ( a -> b )

data Coverage a b = Coverage ((a -> b), [a] ) 

	
instance Coverages Coverage where
	new_cov a f = (Coverage ( f , a ))
	evaluate f o 
		| (( elem o (domain f) ) == True ) = Just ((fun f) o)	
		| otherwise = Nothing
	domain (Coverage (f, a ) ) = a
	num f = length (domain f)
	values f  = map (fun f) (domain f)
	fun (Coverage (f,_) ) = f