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use {List, Queue};
pub trait Try<E> {
type Ok;
fn try(self) -> Result<Self::Ok, E>;
}
impl<E> Try<E> for List<()> {
type Ok = List<()>;
fn try(self) -> Result<List<()>, E> {
Ok(self)
}
}
impl<E, H, T, Z> Try<E> for List<(Result<H, E>, T)>
where T: Try<E, Ok=Z>
{
type Ok = List<(H, Z)>;
fn try(self) -> Result<List<(H, Z)>, E> {
let List((head, tail)) = self;
let head = head?;
let tail = tail.try()?;
Ok(List((head, tail)))
}
}
impl<E> Try<E> for Queue<()> {
type Ok = Queue<()>;
fn try(self) -> Result<Queue<()>, E> {
Ok(self)
}
}
impl<E, H, T, Z> Try<E> for Queue<(H, Result<T, E>)>
where H: Try<E, Ok=Z>
{
type Ok = Queue<(Z, T)>;
fn try(self) -> Result<Queue<(Z, T)>, E> {
let Queue((head, tail)) = self;
let head = head.try()?;
let tail = tail?;
Ok(Queue((head, tail)))
}
}