Data.ProtoLens.Field

An implementation of overloaded record fields. This module enables different types in the same module to have fields of the same name.

To use instances from this class, either:

• Enable the OverloadedLabels extension and import Data.ProtoLens.Labels ();
• Use the field function along with the TypeApplications extension; or,
• Import the corresponding names from the autogenerated *_Fields module.

For more information, see https://google.github.io/proto-lens/tutorial.html#field-overloading.

Documentation

class HasField s (x :: Symbol) a | s x -> a where

A type class for lens fields.

The instance HasField s x a can be understood as "s has a field named x of type a".

Methods

fieldOf :: Functor f => Proxy# x -> (a -> f a) -> s -> f s

field :: forall x s a f. (HasField s x a, Functor f) => (a -> f a) -> s -> f s

A lens for a given field. For example:

view field@"abc" x
set field@"abc" 42 x