use crate::functor::Functor;
use crate::hkt::HKT;
pub trait Extend<A, B>: Functor<A, B> + Sized {
fn extend<W>(self, f: W) -> <Self as HKT<A, B>>::Target
where
W: FnOnce(Self) -> B;
}
impl<A, B> Extend<A, B> for Option<A> {
fn extend<W>(self, f: W) -> Self::Target
where
W: FnOnce(Self) -> B,
{
self.map(|x| f(Some(x)))
}
}