Trait AndThen

pub trait AndThen<O, E>: Sized {
    // Required methods
    fn and_then_ok<F, O2>(self, _: F) -> AndThenOk<Self, F> 
       where F: FnMut(O) -> Result<O2, E>;
    fn and_then_err<F, E2>(self, _: F) -> AndThenErr<Self, F> 
       where F: FnMut(E) -> Result<O, E2>;
}

Extension trait for Iterator<Item = Result<O, E>> to selectively transform Oks and Errors.

Required Methods

fn and_then_ok<F, O2>(self, _: F) -> AndThenOk<Self, F>

where F: FnMut(O) -> Result<O2, E>,

Map oks selectively, possibly converting them to errors

use resiter::and_then::AndThen;
use std::str::FromStr;

let mapped: Vec<_> = ["1", "2", "a", "b", "4", "5"]
    .iter()
    .map(|txt| usize::from_str(txt))
    .and_then_ok(|i| Ok(2 * i))
    .collect();

assert_eq!(mapped[0], Ok(2));
assert_eq!(mapped[1], Ok(4));
assert!(mapped[2].is_err());
assert!(mapped[3].is_err());
assert_eq!(mapped[4], Ok(8));
assert_eq!(mapped[5], Ok(10));

fn and_then_err<F, E2>(self, _: F) -> AndThenErr<Self, F>

where F: FnMut(E) -> Result<O, E2>,

Map errors selectively, possibly converting them to Oks

use resiter::and_then::AndThen;
use std::str::FromStr;

let mapped: Vec<_> = ["1", "2", "a", "b", "4", "5"]
    .iter()
    .map(|txt| usize::from_str(txt).map_err(|e| (txt, e)))
    .and_then_err(|(txt, e)| if txt == &"a" { Ok(15) } else { Err(e) })
    .collect();

assert_eq!(mapped[0], Ok(1));
assert_eq!(mapped[1], Ok(2));
assert_eq!(mapped[2], Ok(15));
assert!(mapped[3].is_err());
assert_eq!(mapped[4], Ok(4));
assert_eq!(mapped[5], Ok(5));

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors

impl<I, O, E> AndThen<O, E> for I

where I: Iterator<Item = Result<O, E>> + Sized,