punk77 2.0.77

Some fun things I've found somewhat helpful
Documentation 
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use std::future::Future;
use std::pin::Pin;
use async_trait::async_trait;
use anyhow::Result;

#[async_trait]
pub trait AndThenAsync<T, U, F>
where
    F: FnOnce(T) -> Pin<Box<dyn Future<Output = U> + Send>> + Send {
    type Output;
    async fn and_then_async(self, map: F) -> Self::Output;
}

#[async_trait]
impl<'a, T, U, F> AndThenAsync<T, U, F> for Option<T>
where
    T: Send,
    U: Send,
    F: 'static + FnOnce(T) -> Pin<Box<dyn Future<Output = U> + Send>> + Send,
{
    type Output = Option<U>;
    async fn and_then_async(self, map: F) -> Self::Output {
        match self {
            Some(t) => {
                let u = map(t).await;
                Some(u)
            }
            None => None,
        }
    }
}

#[async_trait]
impl<'a, T, U, F> AndThenAsync<T, U, F> for Result<T>
where
    T: Send,
    U: Send,
    F: 'static + FnOnce(T) -> Pin<Box<dyn Future<Output = U> + Send>> + Send,
{
    type Output = Result<U>;
    async fn and_then_async(self, map: F) -> Self::Output {
        match self {
            Ok(t) => {
                let u = map(t).await;
                Ok(u)
            }
            Err(e) => Err(e),
        }
    }
}