[Haskell-cafe] point-free ADT pattern matching ?

I wonder if pattern matching could be less verbose. Maybe this sounds weird, but here is example of what I mean:

type A = (Int, String)

f :: String -> A -> A f s (i,s') = (i, s ++ s')

data B = B Int String deriving Show

g :: String -> B -> B g s (B i s') = B i $ s ++ s'

Types A/B and functions f/g are quite similar: (x :: A) or (x :: B) means that x contains some integer and string values, and f/g functions take some string and prepend it to the string part of x. The code for f and g has the same level of verbosity, but -- ta-dah! -- we can use arrows and define f in a highly laconic manner:

import Control.Arrow f' :: String -> A -> A f' = second . (++)

So my queastion is how I could define (g' :: String -> B -> B) in the same way.