module ArrowPlus(module Arrow, module ArrowPlus) where
import Arrow

infixr 6 <|>
infixr 6 <+>

class Arrow q => ArrowZero q where
  zeroA :: q a b

class ArrowZero q => ArrowPlus q where
  (<|>) :: q a b -> q a c -> q a (Either b c) 
  (<+>) :: q a b -> q a b -> q a b            
  -- Default instances:
  f <|> g = (f >>> arr Left) <+> (g >>> arr Right)
  f <+> g = (f <|> g) >>> arr (either id id)