| Safe Haskell | None |
|---|---|
| Language | Haskell2010 |
Bookkeeper.Lens
Contents
Lenses
rlens :: (Settable field val' old new, Gettable field old val, Functor f) => Key field -> (val -> f val') -> Book' old -> f (Book' new) Source #
Build a lens from a field
julian ^. rlens #age = 28
Symbols can also be used directly as lenses, so you probably don't need to use rlens:
julian ^. #age = 28
julian & #age .~ 29
= Book {age = 29, name = "Julian K. Arni"}