lenses.txt

Getter notation: obj^.a.b.c
Setter notation: obj &a.b.c .~ x
Modify notation: obj &a.b.c %~ f

Monadic getter: x <- use a.b.c
Monadic setter: a.b.c .= x 
Monadic modify: a.b.c %= f

zoom :: Monad m => SimpleLensLike (k c) t s -> m c -> n c