Bulat Ziganshin wrote:
Language.Haskell.TH.Lib is full of definitions like this:
infixP p1 n p2 = do p1' <- p1 p2' <- p2 return (InfixP p1' n p2')
btw, such definitions can be simplified by using liftM/ap operations:
instance (Monad m, MyNum v) => MyNum (m v) where (.+) = liftM2 (.+)
Such simplified forms then occur often enough that, in a scrapping boilerplate kind of way, I would really like to be able to write something like instance (Monad m, MyNum v) => MyNum (m v) via lifting or lifted instance (Monad m, MyNum v) => MyNum (m v) or derived instance (Monad m, MyNum v) => MyNum (m v) where all the operations from MyNum are obtained via applying the correct arity liftM function from the Monad class. Jacques