Best way to work around not being apple to partially apply type families?

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
type family MyFun (a :: k1) :: k2

data F1 a b
data F2 a

type instance MyFun (F1 a b) = ???
type instance MyFun (F2 a) = ???

data A g = A MyFun (g Int)

g :: A (F1 String)
g = undefined

-- Is there a better way?