1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47
use std::marker::PhantomData; use crate::internal::functional::{ nat::*, row::*, }; pub struct Either<A, B> { phantom: PhantomData<(A, B)>, } impl<A, B> ToRow for Either<A, B> { type Row = (A, (B, ())); } pub type EitherRow<A, B> = Sum<A, Sum<B, Bottom>>; #[allow(non_upper_case_globals)] pub const LeftLabel: ChoiceSelector<Z> = <ChoiceSelector<Z>>::new(); #[allow(non_upper_case_globals)] pub const RightLabel: ChoiceSelector<S<Z>> = <ChoiceSelector<S<Z>>>::new(); pub enum EitherChoice<A, B> { Left(A), Right(B), } pub use EitherChoice::{ Left, Right, }; impl<A, B> From<Sum<A, Sum<B, Bottom>>> for EitherChoice<A, B> { fn from(row: Sum<A, Sum<B, Bottom>>) -> EitherChoice<A, B> { match row { Sum::Inl(a) => Left(a), Sum::Inr(Sum::Inl(b)) => Right(b), Sum::Inr(Sum::Inr(bot)) => match bot {}, } } }