Data.Lens.Iso.Newtype

_Newtype :: forall t a s b. Newtype t a => Newtype s b => Iso t s a b

An Iso between a newtype and its inner type. This is a specialization of coerced restricted to newtypes. Supports switching between different types that have instances of the Newtype type class. If you don't need to change types, you may have a better experience with type inference if you use simple _Newtype.

unto :: forall n o. Newtype n o => (o -> n) -> Iso' n o

A variant of _Newtype which takes the constructor as an argument and infers its inverse.

This is useful as an aid to type inference in certain situations.