Derive Macro timrs_hkt_macro::HKT

#[derive(HKT)]

Macro for deriving implementations of crate::hkt!.

Arity of the Higher-Kinded Type is automatically defined based on the implementing type arity.

Examples

use timrs_hkt_macro::{hkt, HKT};

/* The parameter indicates the arity of the Higher-Kinded Type trait to be generated */
hkt!(1);

trait Functor: HKT1 {
    fn map<B, F>(self, f: F) -> Self::With<B>
    where
        F: FnMut(Self::T1) -> B;
}

#[derive(HKT, Debug, PartialEq)]
enum Example1<A> {
    First(A),
}

impl<A> Functor for Example1<A> {
    fn map<B, F>(self, mut f: F) -> Self::With<B>
    where
        F: FnMut(Self::T1) -> B,
    {
        match self {
            Self::First(a) => Example1::First(f(a)),
        }
    }
}

assert_eq!(
    Example1::First("The magic number is 42".to_owned()),
    Example1::First(42).map(|x| "The magic number is ".to_owned() + &x.to_string())
);