Function call 

pub async fn call<P, F, Args, Err>(
    provider: &P,
    func: F,
) -> Result<F::Output, Err>
where
    P: Extract<Args, Err>,
    F: Caller<Args, P, Err>,
    Err: Error,

Use a provider to call a function

Example

use extractors::{call, Extract};

async fn add(a: i32, b: i32) -> i32 {
    a + b
}

struct Example(i32);

#[derive(Debug)]
struct Err;

impl Display for Err {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(f, "Err")
    }
}

impl Error for Err {}

impl Extract<i32, Err> for Example {
    fn extract<'a>(&'a self) -> Pin<Box<dyn Future<Output = Result<i32, Err>> + 'a>> {
        Box::pin(std::future::ready(Ok(self.0)))
    }
}

let example = Example(1);
let result = call(&example, add).await;