import "JavaBuiltin" as Java

importJava "org.simantics.scl.runtime.Lists" where
    foldl :: (a -> b -> a) -> a -> [b] -> a

class Additive a where
    zero :: a
    (+)  :: a -> a -> a    
    
    sum  :: [a] -> a
    sum = foldl (+) zero    
    
instance (Additive a, Additive b, Additive c) => Additive (a, b, c) where
    zero = (zero, zero, zero)
    (a0, b0, c0) + (a1, b1, c1) = (a0+a1, b0+b1, c0+c1)
    
main = "OK"
--
OK