Struct Reader 

pub struct Reader<R, A> { /* private fields */ }

A Reader monad: computation depending on a shared environment R.

Implementations

impl<R: 'static, A: 'static> Reader<R, A>

pub fn new(f: impl FnOnce(&R) -> A + 'static) -> Self

Create a Reader from a function.

pub fn pure(a: A) -> Self

where A: Clone,

Lift a pure value.

pub fn bind<B: 'static>( self, f: impl FnOnce(A) -> Reader<R, B> + 'static, ) -> Reader<R, B>

Monadic bind.

pub fn map<B: 'static>(self, f: impl FnOnce(A) -> B + 'static) -> Reader<R, B>

Map over the result.

pub fn run(self, env: &R) -> A

Run the computation with an environment.

pub fn ask() -> Reader<R, R>

where R: Clone,

Ask for the full environment.

pub fn asks<B: 'static>(f: impl FnOnce(&R) -> B + 'static) -> Reader<R, B>

Ask for a projection of the environment.