Trait im::lens::PartialLens

pub trait PartialLens: Clone {
    type From;
    type To;
    fn try_get(&self, s: &Self::From) -> Option<Arc<Self::To>>;
    fn try_put<Convert>(
        &self, 
        v: Option<Convert>, 
        s: &Self::From
    ) -> Option<Self::From>
    where
        Convert: Shared<Self::To>;

    fn try_chain<L, Next>(
        &self, 
        next: &L
    ) -> Compose<Self::From, Self::To, Next, Self, L>
    where
        L: PartialLens<From = Self::To, To = Next>,
    { ... }
}

A lens from From to To where the focus of the lens isn't guaranteed to exist inside From. Operations on these lenses therefore return Options.

Associated Types

type From

type To

Required Methods

fn try_get(&self, s: &Self::From) -> Option<Arc<Self::To>>

Get the focus of the lens, if available.

fn try_put<Convert>(
    &self,
    v: Option<Convert>,
    s: &Self::From
) -> Option<Self::From> where
    Convert: Shared<Self::To>, 

Put a value into the lens, returning the updated From value if the operation succeeded.

Provided Methods

fn try_chain<L, Next>(
    &self,
    next: &L
) -> Compose<Self::From, Self::To, Next, Self, L> where
    L: PartialLens<From = Self::To, To = Next>, 

Compose this lens with a lens from To to a new type Next, yielding a lens from From to Next.

Implementors

• impl<K, V> PartialLens for MapLens<K, V> where
    K: Ord,  type From = Map<K, V>; type To = V;
• impl<A, B, C, L, R> PartialLens for Compose<A, B, C, L, R> where
    L: PartialLens<From = A, To = B>,
    R: PartialLens<From = B, To = C>,  type From = A; type To = C;
• impl<A, B> PartialLens for GeneralLens<A, B> type From = A; type To = B;